Updates from April, 2017 Toggle Comment Threads | Keyboard Shortcuts

  • Joseph Nebus 6:00 pm on Sunday, 9 April, 2017 Permalink | Reply
    Tags: , chess, , , , Mustard and Boloney, , , , Take It From The Tinkersons,   

    Reading the Comics, April 6, 2017: Abbreviated Week Edition 

    I’m writing this a little bit early because I’m not able to include the Saturday strips in the roundup. There won’t be enough to make a split week edition; I’ll just add the Saturday strips to next week’s report. In the meanwhile:

    Mac King and Bill King’s Magic in a Minute for the 2nd is a magic trick, as the name suggests. It figures out a card by way of shuffling a (partial) deck and getting three (honest) answers from the other participant. If I’m not counting wrongly, you could do this trick with up to 27 cards and still get the right card after three answers. I feel like there should be a way to explain this that’s grounded in information theory, but I’m not able to put that together. I leave the suggestion here for people who see the obvious before I get to it.

    Bil Keane and Jeff Keane’s Family Circus (probable) rerun for the 6th reassured me that this was not going to be a single-strip week. And a dubiously included single strip at that. I’m not sure that lotteries are the best use of the knowledge of numbers, but they’re a practical use anyway.

    Dolly holds up pads of paper with numbers on them. 'C'mon, PJ, you hafta learn your numbers or else you'll never win the lottery.'

    Bil Keane and Jeff Keane’s Family Circus for the 6th of April, 2017. I’m not familiar enough with the evolution of the Family Circus style to say whether this is a rerun, a newly-drawn strip, or an old strip with a new caption. I suppose there is a certain timelessness to it, at least once we get into the era when states sported lotteries again.

    Bill Bettwy’s Take It From The Tinkersons for the 6th is part of the universe of students resisting class. I can understand the motivation problem in caring about numbers of apples that satisfy some condition. In the role of distinct objects whose number can be counted or deduced cards are as good as apples. In the role of things to gamble on, cards open up a lot of probability questions. Counting cards is even about how the probability of future events changes as information about the system changes. There’s a lot worth learning there. I wouldn’t try teaching it to elementary school students.

    The teacher: 'How many apples will be left, Tillman?' 'When are we going to start counting things more exciting than fruit?' 'What would you like to count, Tillman?' 'Cards.'

    Bill Bettwy’s Take It From The Tinkersons for the 6th of April, 2017. That tree in the third panel is a transplant from a Slylock Fox six-differences panel. They’ve been trying to rebuild the population of trees that are sometimes three triangles and sometimes four triangles tall.

    Jeffrey Caulfield and Alexandre Rouillard’s Mustard and Boloney for the 6th uses mathematics as the stuff know-it-alls know. At least I suppose it is; Doctor Know It All speaks of “the pathagorean principle”. I’m assuming that’s meant to be the Pythagorean theorem, although the talk about “in any right triangle the area … ” skews things. You can get to stuf about areas of triangles from the Pythagorean theorem. One of the shorter proofs of it depends on the areas of the squares of the three sides of a right triangle. But it’s not what people typically think of right away. But he wouldn’t be the first know-it-all to start blathering on the assumption that people aren’t really listening. It’s common enough to suppose someone who speaks confidently and at length must know something.

    Dave Whamond’s Reality Check for the 6th is a welcome return to anthropomorphic-numerals humor. Been a while.

    Zach Weinersmith’s Saturday Morning Breakfast Cereal for the 6th builds on the form of a classic puzzle, about a sequence indexed to the squares of a chessboard. The story being riffed on is a bit of mathematical legend. The King offered the inventor of chess any reward. The inventor asked for one grain of wheat for the first square, two grains for the second square, four grains for the third square, eight grains for the fourth square, and so on, through all 64 squares. An extravagant reward, but surely one within the king’s power to grant, right? And of course not: by the 64th doubling the amount of wheat involved is so enormous it’s impossibly great wealth.

    The father’s offer is meant to evoke that. But he phrases it in a deceptive way, “one penny for the first square, two for the second, and so on”. That “and so on” is the key. Listing a sequence and ending “and so on” is incomplete. The sequence can go in absolutely any direction after the given examples and not be inconsistent. There is no way to pick a single extrapolation as the only logical choice.

    We do it anyway, though. Even mathematicians say “and so on”. This is because we usually stick to a couple popular extrapolations. We suppose things follow a couple common patterns. They’re polynomials. Or they’re exponentials. Or they’re sine waves. If they’re polynomials, they’re lower-order polynomials. Things like that. Most of the time we’re not trying to trick our fellow mathematicians. Or we know we’re modeling things with some physical base and we have reason to expect some particular type of function.

    In this case, the $1.27 total is consistent with getting two cents for every chess square after the first. There are infinitely many other patterns that would work, and the kid would have been wise to ask for what precisely “and so on” meant before choosing.

    Berkeley Breathed’s Bloom County 2017 for the 7th is the climax of a little story in which Oliver Wendell Holmes has been annoying people by shoving scientific explanations of things into their otherwise pleasant days. It’s a habit some scientifically-minded folks have, and it’s an annoying one. Many of us outgrow it. Anyway, this strip is about the curious evidence suggesting that the universe is not just expanding, but accelerating its expansion. There are mathematical models which allow this to happen. When developing General Relativity, Albert Einstein included a Cosmological Constant for little reason besides that without it, his model would suggest the universe was of a finite age and had expanded from an infinitesimally small origin. He had grown up without anyone knowing of any evidence that the size of the universe was a thing that could change.

    Anyway, the Cosmological Constant is a puzzle. We can find values that seem to match what we observe, but we don’t know of a good reason it should be there. We sciencey types like to have models that match data, but we appreciate more knowing why the models look like that and not anything else. So it’s a good problem some of the cosmologists have been working on. But we’ve been here before. A great deal of physics, especially in the 20th Century, has been driven by looking for reasons behind what look like arbitrary points in a successful model. If Oliver were better-versed in the history of science — something scientifically minded people are often weak on, myself included — he’d be less easily taunted by Opus.

    Mikael Wulff and Anders Morgenthaler’s TruthFacts for the 7th thinks that we forgot they ran this same strip back on the 17th of March. I spotted it, though. Nyah.

  • Joseph Nebus 6:00 pm on Thursday, 6 April, 2017 Permalink | Reply
    Tags: , , Imogen Quest, , , Sticky Comics, , Wizard of Id   

    Reading the Comics, April 1, 2017: Connotations Edition 

    Last week ended with another little string of mathematically-themed comic strips. Most of them invited, to me, talk about the cultural significance of mathematics and what connotations they have. So, this title for an artless essay.

    Berkeley Breathed’s Bloom County 2017 for the 28th of March uses “two plus two equals” as the definitive, inarguable truth. It always seems to be “two plus two”, doesn’t it? Never “two plus three”, never “three plus three”. I suppose I’ve sometimes seen “one plus one” or “two times two”. It’s easy to see why it should be a simple arithmetic problem, nothing with complicated subtraction or division or numbers as big as six. Maybe the percussive alliteration of those repeated two’s drives the phrase’s success. But then why doesn’t “two times two” show up nearly as often? Maybe the phrase isn’t iambic enough. “Two plus two” allows (to my ear) the “plus” sink in emphasis, while “times” stays a little too prominent. We need a wordsmith in to explore it. (I’m open to other hypotheses, including that “two times two” gets used more than my impression says.)

    Christiann MacAuley’s Sticky Comics for the 28th uses mathematics as the generic “more interesting than people” thing that nerds think about. The thing being thought of there is the Mandelbrot Set. It’s built on complex-valued numbers. Pick a complex number, any you like; that’s called ‘C’. Square the number and add ‘C’ back to itself. This will be some new complex-valued number. Square that new number and add the original ‘C’ back to it again. Square that new number and add the original ‘C’ back once more. And keep at this. There are two things that might happen. These squared numbers might keep growing infinitely large. They might be negative, or imaginary, or (most likely) complex-valued, but their size keeps growing. Or these squared numbers might not grow arbitrarily large. The Mandelbrot Set is the collection of ‘C’ values for which the numbers don’t just keep growing in size. That’s the sort of lumpy kidney bean shape with circles and lightning bolts growing off it that you saw on every pop mathematics book during the Great Fractal Boom of the 80s and 90s. There’s almost no point working it out in your head; the great stuff about fractals almost requires a computer. They take a lot of computation. But if you’re just avoiding conversation, well, anything will do.

    Olivia Walch’s Imogen Quest for the 29th riffs on the universe-as-simulation hypothesis. It’s one of those ideas that catches the mind and is hard to refute as long as we don’t talk to the people in the philosophy department, which we’re secretly scared of. Anyway the comic shows one of the classic uses of statistical modeling: try out a number of variations of a model in the hopes of understanding real-world behavior. This is an often-useful way to balance how the real world has stuff going on that’s important and that we don’t know about, or don’t know how to handle exactly.

    Mason Mastroianni’s The Wizard of Id for the 31st uses a sprawl of arithmetic as symbol of … well, of status, really. The sort of thing that marks someone a white-collar criminal. I suppose it also fits with the suggestion of magic that accompanies huge sprawls of mathematical reasoning. Bundle enough symbols together and it looks like something only the intellectual aristocracy, or at least secret cabal, could hope to read.

    Bob Shannon’s Tough Town for the 1st name-drops arithmetic. And shows off the attitude that anyone we find repulsive must also be stupid, as proven by their being bad at arithmetic. I admit to having no discernable feelings about the Kardashians; but I wouldn’t be so foolish as to conflate intelligence and skill-at-arithmetic.

    • elkement (Elke Stangl) 3:24 pm on Thursday, 20 April, 2017 Permalink | Reply

      I am replying to the previous post (March statistics) – as nothing happened when I clicked on the reply button at that post. But maybe this is related to what I actually wanted to comment about:

      Your table is displayed at the bottom of the page – below ‘Related’, the comment box, and the previous/next posting links! How did you do this? You totally hacked WordPress ;-)


      • elkement (Elke Stangl) 3:25 pm on Thursday, 20 April, 2017 Permalink | Reply

        OK – so that reply could be posted. As I said, with your table you confused WordPress a lot :-)


      • Joseph Nebus 2:43 am on Tuesday, 25 April, 2017 Permalink | Reply

        Huh, and that’s curious. I didn’t realize it and must not have looked close enough at the preview.

        It looks like the fault is that I failed to close the table tag, so WordPress tried to fit the rest of the page in-between the tbody and the end of the table and goodness knows how it worked out that presentation.

        Liked by 1 person

  • Joseph Nebus 6:00 pm on Wednesday, 5 April, 2017 Permalink | Reply
    Tags: , March, , ,   

    How March 2017 Treated My Mathematics Blog 

    It’s a good time for my occasional review of how blogging here is going. And it turns out from WordPress’s statistics that apparently I don’t need to blog anymore for things to turn out all right. But March ended up a slow and outright lazy month for me, with only twelve posts (one of them the monthly statistics report) and I feared what would happen to my readership numbers.

    Turns out, nothing. There were 1,026 page views in March from 699 unique visitors. In February there’d been 1,063 views from 680 unique visitors, and in January some 1,031 page views from 586 unique visitors. That’s reassuring, especially as I work out when I’m going to have the energy for a new A to Z sequence.

    Oh, reader engagement might have dropped, since most of what I wrote was Reading the Comics posts and they’re pretty closed topics. I can’t think of a way to turn “here’s one where the student misinterprets the word problem” into something debatable. Maybe “here’s one where the student does not misinterpret the word problem”, since posting an error is the surest way to get a correction. There were only 15 comments in March, down from February’s 18 and way down from January’s 34. Maybe I need to do a blog potluck or something to encourage chatter. I was slightly more liked, though. There were 85 likes clicked around here in March. This is technically different from February’s 77 and January’s 97.

    Three of the month’s top five articles were ones I would have expected. One is becoming a perennial. The remarkable thing to me is none of my March Madness themed pieces was a top-five. Maybe everyone was too angry about their brackets collapsing the first day. But popular were:

    Among the popular search terms this month were:

    • isosceles trapezoid pretty
    • what are the priorities of teen agers 20 years ago and in the present? venn diagram
    • origin is the gateway to your entire gaming universe
    • how many grooves on a vinyl record
    • teetotallers might get a laugh out of this jumble
    • cartoon spank bot 3000
    • comics about law of conservation

    Yeah, I’m not putting some of those terms into Google. I’m scared enough after I searched on a technical issue and got the note that there were some more results I could see if I turned Safe Search off. I don’t know what might be in there but I don’t need to see that.

    Here’s the roster of countries and page views:

    Country Views
    United States 661
    Canada 42
    India 37
    Philippines 31
    United Kingdom 30
    Australia 27
    Germany 19
    Singapore 18
    Turkey 13
    Sweden 13
    South Africa 12
    Austria 8
    Brazil 8
    Netherlands 8
    Puerto Rico 8
    Spain 7
    France 6
    Belgium 5
    Italy 5
    Mexico 5
    Oman 5
    South Korea 4
    Portugal 3
    Argentina 2
    Hungary 2
    Indonesia 2
    Iraq 2
    New Zealand 2
    Norway 2
    Uruguay 2
    Algeria 1 (*)
    Bulgaria 1
    Chile 1
    Colombia 1
    Czech Republic 1
    Denmark 1
    Finland 1
    Georgia 1
    Greece 1
    Hong Kong SAR China 1
    Ireland 1 (*)
    Jamaica 1
    Malaysia 1
    Malta 1
    Pakistan 1
    Peru 1
    Romania 1 (*)
    Saudi Arabia 1 (*)
    Serbia 1
    Slovakia 1
    Slovenia 1
    Switzerland 1
    Taiwan 1 (*)
    Thailand 1
    Trinidad and Tobago 1
    Vietnam 1 (*)

    I make that out to be 56 separate countries, not counting the “European Union” since that mystery wasn’t there. That’s down from February’s 64 and about back to January’s 53. There were, I estimate, 26 single-reader countries, up from February’s 22 and January’s 13. Algeria, Ireland, Romania, Saudi Arabia, Taiwan, and Vietnam were all single-reader countries in February. Nobody’s on a three-month streak.

    The month started with 47,224 recorded visits from a stated 20,854 distinct readers. Insights tells me the most popular hour was 6 pm, as expected. It’s when stuff is normally posted. 12 percent of views came that hour, up from 11 percent in February and 10 percent in March. Tuesday was the most popular day, with 18 percent of views. In February it was Monday, with 16 percent, and in January it was Thursdays again with 16 percent. This is all so close to one-seventh that I figure there’s no real difference in readership per day.

    WordPress thinks I started the month with 650 followers on the site, up from 642 at the start of February. You can be one of those WordPress viewers by using the ‘Follow On WordPress’ button that’s in the upper-right corner as I see the page. Or you can follow by e-mail. There’s other people who do that. You won’t be totally weird if you do. And again, I am on Twitter, as @nebusj, so perhaps you’d like the experience of me in fewer characters. I understand.

  • Joseph Nebus 6:00 pm on Sunday, 2 April, 2017 Permalink | Reply
    Tags: , , Baldo, Big Top, ,   

    Reading the Comics, March 27, 2017: Not The March 26 Edition 

    My guide for how many comics to include in one of these essays is “at least five, if possible”. Occasionally there’s a day when Comic Strip Master Command sends that many strips at once. Last Sunday was almost but not quite such a day. But the business of that day did mean I had enough strips to again divide the past week’s entries. Look for more comics in a few days, if all goes well here. Thank you.

    Mark Anderson’s Andertoons for the 26th reminds me of something I had wholly forgot about: decimals inside fractions. And now that this little horror’s brought back I remember my experience with it. Decimals in fractions aren’t, in meaning, any different from division of decimal numbers. And the decimals are easily enough removed. But I get the kid’s horror. Fractions and decimals are both interesting in the way they represent portions of wholes. They spend so much time standing independently of one another it feels disturbing to have them interact. Well, Andertoons kid, maybe this will comfort you: somewhere along the lines decimals in fractions just stop happening. I’m not sure when. I don’t remember when the last one passed my experience.

    Hector Cantu and Carlos Castellanos’s Baldo for the 26th is built on a riddle. It’s one that depends on working in shifting addition from “what everybody means by addition” to “what addition means on a clock”. You can argue — I’m sure Gracie would — that “11 plus 3” does not mean “eleven o’clock plus three hours”. But on what grounds? If it’s eleven o’clock and you know something will happen in three hours, “two o’clock” is exactly what you want. Underlying all of mathematics are definitions about what we mean by stuff like “eleven” and “plus” and “equals”. And underlying the definitions is the idea that “here is a thing we should like to know”.

    Addition of hours on a clock face — I never see it done with minutes or seconds — is often used as an introduction to modulo arithmetic. This is arithmetic on a subset of the whole numbers. For example, we might use 0, 1, 2, and 3. Addition starts out working the way it does in normal numbers. But then 1 + 3 we define to be 0. 2 + 3 is 1. 3 + 3 is 2. 2 + 2 is 0. 2 + 3 is 1 again. And so on. We get subtraction the same way. This sort of modulo arithmetic has practical uses. Many cryptography schemes rely on it, for example. And it has pedagogical uses; modulo arithmetic turns up all over a mathematics major’s Introduction to Not That Kind Of Algebra Course. You can use it to learn a lot of group theory with something a little less exotic than rotations and symmetries of polygonal shapes or permutations of lists of items. A clock face doesn’t quite do it, though. We have to pretend the ’12’ at the top is a ‘0’. I’ve grown more skeptical about whether appealing to clocks is useful in introducing modulo arithmetic. But it’s been a while since I’ve needed to discuss the matter at all.

    Rob Harrell’s Big Top rerun for the 26th mentions sudoku. Remember when sudoku was threatening to take over the world, or at least the comics page? Also, remember comics pages? Good times. It’s not one of my hobbies, but I get the appeal.

    Bob Shannon’s Tough Town I’m not sure if I’ve featured here before. It’s one of those high concept comics. The patrons at a bar are just what you see on the label, and there’s a lot of punning involved. Now that I’ve over-explained the joke please enjoy the joke. There are a couple of strips prior to this one featuring the same characters; they just somehow didn’t mention enough mathematics words for me to bring up here.

    Overhearing customers: 'Kids today can't even do basic math. If the computer doesn't tell them how much change to give you, they don't know what to do.' Customer asking: 'How much is 50% off of $49.99 ? Does that mean it's free?' Clerk: Sigh.

    Norm Feuti’s Retail for the 27th of March, 2017. Of course customers aren’t generally good at arithmetic either. I’m reminded (once more) of when I worked at Walden Books and a customer wanted to know whether the sticker-promised 10 percent discount on the book was applied to the price before or after the 6 percent sales tax was added to it, or whether it was applied afterwards. I could not speak to the cash register’s programming, but I could promise that the process would come to the same number either way, and I told him what it would be. I think the book had a $14.95 cover price — let’s stipulate it was for the sake of my anecdote — so it would come to $14.26 in the end. He judged me suspiciously and then allowed me to ring it up; the register made it out to be $15.22 and he pounced, saying, see?. Yes: he had somehow found the one freaking book in the store where the UPC bar code price, $15.95, was different from the thing listed as the cover price. I told him why it was and showed him where in the UPC to find the encoded price (it’s in the last stanza of digits underneath the bars) but he was having none of it, even when I manually corrected the error.

    Norm Feuti’s Retail for the 27th is about the great concern-troll of mathematics education: can our cashiers make change? I’m being snottily dismissive. Shops, banks, accountants, and tax registries are surely the most common users of mathematics — at least arithmetic — out there. And if people are going to do a thing, ordinarily, they ought to be able to do it well. But, of course, the computer does arithmetic extremely well. Far better, or at least more indefatigably, than any cashier is going to be able to do. The computer will also keep track of the prices of everything, and any applicable sales or discounts, more reliably than the mere human will. The whole point of the Industrial Revolution was to divide tasks up and assign them to parties that could do the separate parts better. Why get worked up about whether you imagine the cashier knows what $22.14 minus $16.89 is?

    I will say the time the bookstore where I worked lost power all afternoon and we had to do all the transactions manually we ended up with only a one-cent discrepancy in the till, thank you.

    • The Chaos Realm 1:05 pm on Monday, 3 April, 2017 Permalink | Reply

      Forget school-taught math, that’s how I best learned math…as a cashier…


      • Joseph Nebus 2:18 am on Tuesday, 4 April, 2017 Permalink | Reply

        I shouldn’t be surprised! Doing anything often will encourage people to find more accurate and faster ways to do it. So one speeds up either by just being better at recognizing common operations or by developing useful shortcuts. (The shortcuts can be disastrous if, for example, they accidentally cause some needed safety precaution not to be taken, but that doesn’t tend to apply in cashier work.)

        Liked by 1 person

        • The Chaos Realm 2:29 am on Tuesday, 4 April, 2017 Permalink | Reply

          Yeah, I used to drive my math teachers crazy with my shortcuts. But, I love when I see the light bulb go off in kids when I show them other ways to do math problems (even as a sub, I do sometimes get to teach :-) )


          • Joseph Nebus 5:23 am on Friday, 14 April, 2017 Permalink | Reply

            There is that. A weird shortcut or novel trick for a problem, even if it doesn’t lead to a generally useful technique, is good to have on the record. It inspires the imagination and lets folks know that there’s almost never just one way to do things.

            Liked by 1 person

    • davekingsbury 9:10 pm on Monday, 3 April, 2017 Permalink | Reply

      Guestimation keeps the common sense in maths I, er … guess. As for Sudoku, is there any other way to do it than listing all possible #s in each box? I see people on buses and trains just staring at it – are they hoping for inspiration or else doing prodigious memory work?


      • Joseph Nebus 2:23 am on Tuesday, 4 April, 2017 Permalink | Reply

        I’m not an expert sudoku solver. I’d done some for a little while, especially after some students gave me a book of puzzles as a parting gift, but I never caught the bug.

        But when I do them, it is … I wouldn’t say a prodigious amount of memory work. It would be picking out a cell and checking what the valid possible numbers are, then going across the row, column, and cell to see if there were any obvious contradictions, or whether that forced something suspicious in a nearby cell. I don’t suppose that works well for hard puzzles, but for the silly little easy and almost-medium puzzles I attacked it was fine. Something would turn up soon.

        Liked by 1 person

  • Joseph Nebus 6:00 pm on Friday, 31 March, 2017 Permalink | Reply
    Tags: , bridge, , , ,   

    How Much Might I Have Lost At Pinball? 

    After the state pinball championship last month there was a second, side tournament. It was a sort-of marathon event in which I played sixteen games in short order. I won three of them and lost thirteen, a disheartening record. The question I can draw from this: was I hopelessly outclassed in the side tournament? Is it plausible that I could do so awfully?

    The answer would be “of course not”. I was playing against, mostly, the same people who were in the state finals. (A few who didn’t qualify for the finals joined the side tournament.) In that I had done well enough, winning seven games in all out of fifteen played. It’s implausible that I got significantly worse at pinball between the main and the side tournament. But can I make a logically sound argument about this?

    In full, probably not. It’s too hard. The question is, did I win way too few games compared to what I should have expected? But what should I have expected? I haven’t got any information on how likely it should have been that I’d win any of the games, especially not when I faced something like a dozen different opponents. (I played several opponents twice.)

    But we can make a model. Suppose that I had a fifty percent chance of winning each match. This is a lie in detail. The model contains lies; all models do. The lies might let us learn something interesting. Some people there I could only beat with a stroke of luck on my side. Some people there I could fairly often expect to beat. If we pretend I had the same chance against everyone, though, we get something that we can model. It might tell us something about what really happened.

    If I play 16 matches, and have a 50 percent chance of winning each of them, then I should expect to win eight matches. But there’s no reason I might not win seven instead, or nine. Might win six, or ten, without that being too implausible. It’s even possible I might not win a single match, or that I might win all sixteen matches. How likely?

    This calls for a creature from the field of probability that we call the binomial distribution. It’s “binomial” because it’s about stuff for which there are exactly two possible outcomes. This fits. Each match I can win or I can lose. (If we tie, or if the match is interrupted, we replay it, so there’s not another case.) It’s a “distribution” because we describe, for a set of some number of attempted matches, how the possible outcomes are distributed. The outcomes are: I win none of them. I win exactly one of them. I win exactly two of them. And so on, all the way up to “I win exactly all but one of them” and “I win all of them”.

    To answer the question of whether it’s plausible I should have done so badly I need to know more than just how likely it is I would win only three games. I need to also know the chance I’d have done worse. If I had won only two games, or only one, or none at all. Why?

    Here I admit: I’m not sure I can give a compelling reason, at least not in English. I’ve been reworking it all week without being happy at the results. Let me try pieces.

    One part is that as I put the question — is it plausible that I could do so awfully? — isn’t answered just by checking how likely it is I would win only three games out of sixteen. If that’s awful, then doing even worse must also be awful. I can’t rule out even-worse results from awfulness without losing a sense of what the word “awful” means. Fair enough, to answer that question. But I made up the question. Why did I make up that one? Why not just “is it plausible I’d get only three out of sixteen games”?

    Habit, largely. Experience shows me that the probability of any particular result turns out to be implausibly low. It isn’t quite that case here; there’s only seventeen possible noticeably different outcomes of playing sixteen games. But there can be so many possible outcomes that even the most likely one isn’t.

    Take an extreme case. (Extreme cases are often good ways to build an intuitive understanding of things.) Imagine I played 16,000 games, with a 50-50 chance of winning each one of them. It is most likely that I would win 8,000 of the games. But the probability of winning exactly 8,000 games is small: only about 0.6 percent. What’s going on there is that there’s almost the same chance of winning exactly 8,001 or 8,002 games. As the number of games increases the number of possible different outcomes increases. If there are 16,000 games there are 16,001 possible outcomes. It’s less likely that any of them will stand out. What saves our ability to predict the results of things is that the number of plausible outcomes increases more slowly. It’s plausible someone would win exactly three games out of sixteen. It’s impossible that someone would win exactly three thousand games out of sixteen thousand, even though that’s the same ratio of won games.

    Card games offer another way to get comfortable with this idea. A bridge hand, for example, is thirteen cards drawn out of fifty-two. But the chance that you were dealt the hand you just got? Impossibly low. Should we conclude from this all bridge hands are hoaxes? No, but ask my mother sometime about the bridge class she took that one cruise. “Three of sixteen” is too particular; “at best three of sixteen” is a class I can study.

    Unconvinced? I don’t blame you. I’m not sure I would be convinced of that, but I might allow the argument to continue. I hope you will. So here are the specifics. These are the chance of each count of wins, and the chance of having exactly that many wins, for sixteen matches:

    Wins Percentage
    0 0.002 %
    1 0.024 %
    2 0.183 %
    3 0.854 %
    4 2.777 %
    5 6.665 %
    6 12.219 %
    7 17.456 %
    8 19.638 %
    9 17.456 %
    10 12.219 %
    11 6.665 %
    12 2.777 %
    13 0.854 %
    14 0.183 %
    15 0.024 %
    16 0.002 %

    So the chance of doing as awfully as I had — winning zero or one or two or three games — is pretty dire. It’s a little above one percent.

    Is that implausibly low? Is there so small a chance that I’d do so badly that we have to figure I didn’t have a 50-50 chance of winning each game?

    I hate to think that. I didn’t think I was outclassed. But here’s a problem. We need some standard for what is “it’s implausibly unlikely that this happened by chance alone”. If there were only one chance in a trillion that someone with a 50-50 chance of winning any game would put in the performance I did, we could suppose that I didn’t actually have a 50-50 chance of winning any game. If there were only one chance in a million of that performance, we might also suppose I didn’t actually have a 50-50 chance of winning any game. But here there was only one chance in a hundred? Is that too unlikely?

    It depends. We should have set a threshold for “too implausibly unlikely” before we started research. It’s bad form to decide afterward. There are some thresholds that are commonly taken. Five percent is often useful for stuff where it’s hard to do bigger experiments and the harm of guessing wrong (dismissing the idea I had a 50-50 chance of winning any given game, for example) isn’t so serious. One percent is another common threshold, again common in stuff like psychological studies where it’s hard to get more and more data. In a field like physics, where experiments are relatively cheap to keep running, you can gather enough data to insist on fractions of a percent as your threshold. Setting the threshold after is bad form.

    In my defense, I thought (without doing the work) that I probably had something like a five percent chance of doing that badly by luck alone. It suggests that I did have a much worse than 50 percent chance of winning any given game.

    Is that credible? Well, yeah; I may have been in the top sixteen players in the state. But a lot of those people are incredibly good. Maybe I had only one chance in three, or something like that. That would make the chance I did that poorly something like one in six, likely enough.

    And it’s also plausible that games are not independent, that whether I win one game depends in some way on whether I won or lost the previous. But it does feel like it’s easier to win after a win, or after a close loss. And it feels harder to win a game after a string of losses. I don’t know that this can be proved, not on the meager evidence I have available. And you can almost always question the independence of a string of events like this. It’s the safe bet.

  • Joseph Nebus 6:00 pm on Sunday, 26 March, 2017 Permalink | Reply
    Tags: , , , , Pardon My Planet, , , , , Todd the Dinosaur   

    Reading the Comics, March 25, 2017: Slow Week Edition 

    Slow week around here for mathematically-themed comic strips. These happen. I suspect Comic Strip Master Command is warning me to stop doing two-a-week essays on reacting to comic strips and get back to more original content. Message received. If I can get ahead of some projects Monday and Tuesday we’ll get more going.

    Patrick Roberts’s Todd the Dinosaur for the 20th is a typical example of mathematics being something one gets in over one’s head about. Of course it’s fractions. Is there anything in elementary school that’s a clearer example of something with strange-looking rules and processes for some purpose students don’t even know what they are? In middle school and high school we get algebra. In high school there’s trigonometry. In high school and college there’s calculus. In grad school there’s grad school. There’s always something.

    Teacher: 'Todd, are you wearing water wings? Why, pray tell?' 'So I can make it to the third grade! We're startin' fractions today and YOU said you had a feeling I was gonna get in over my head.' 'Dang!'

    Patrick Roberts’s Todd the Dinosaur for the 20th of March, 2017. I’ll allow the kids-say-the-darndest-things setup for the strip. I’m stuck on wondering just how much good water wings that size could do. Yes, he’s limited by his anatomy but aren’t we all?

    Jeff Stahler’s Moderately Confused for the 21st is the usual bad-mathematics-of-politicians joke. It may be a little more on point considering the Future Disgraced Former President it names, but the joke is surely as old as politicians and hits all politicians with the same flimsiness.

    John Graziano’s Ripley’s Believe It Or Not for the 22nd names Greek mathematician Pythagoras. That’s close enough to on-point to include here, especially considering what a slow week it’s been. It may not be fair to call Pythagoras a mathematician. My understanding is we don’t know that actually did anything in mathematics, significant or otherwise. His cult attributed any of its individuals’ discoveries to him, and may have busied themselves finding other, unrelated work to credit to their founder. But there’s so much rumor and gossip about Pythagoras that it’s probably not fair to automatically dismiss any claim about him. The beans thing I don’t know about. I would be skeptical of anyone who said they were completely sure.

    Vic Lee’s Pardon My Planet for the 23rd is the usual sort of not-understanding-mathematics joke. In this case it’s about percentages, which are good for baffling people who otherwise have a fair grasp on fractions. I wonder if people would be better at percentages if they learned to say “percent” as “out of a hundred” instead. I’m sure everyone who teaches percentages teaches that meaning, but that doesn’t mean the warning communicates.

    'OK, then let's compromise. I'll be right most of the time - at least 46 percent of the time. And you can be right whenever there is math involved.'

    Vic Lee’s Pardon My Planet for the 23rd of March, 2017. Don’t mind me, I’m busy trying to convince myself the back left leg of that park bench is hidden behind the guy’s leg and not missing altogether and it’s still pretty touch-and-go on that.

    Stephan Pastis’s Pearls Before Swine for the 24th jams a bunch of angle puns into its six panels. I think it gets most of the basic set in there.

    Samson’s Dark Side Of The Horse for the 25th mentions sudokus, and that’s enough for a slow week like this. I thought Horace was reaching for a calculator in the last panel myself, and was going to say that wouldn’t help any. But then I checked the numbers in the boxes and that made it all better.

  • Joseph Nebus 6:00 pm on Friday, 24 March, 2017 Permalink | Reply
    Tags: , , open questions, , Turing machines   

    What Pinball Games Are Turing Machines? 

    I got to thinking about Turing machines. This is the conceptual model for basically all computers. The classic concept is to imagine a string of cells. In each cell is some symbol. It’s gone over by some device that follows some rule about whether and how to change the symbol. We have other rules that let us move the machine from one cell to the next. This doesn’t sound like much. But it’s enough. We can imagine all software to be some sufficiently involved bit of work on a string of cells and changing (or not) the symbols in those cells.

    We don’t normally do this, because it’s too much tedious work. But we know we could go back to this if we truly must. A proper Turing machine has infinitely many cells, which no actual computer does, owing to the high cost of memory chips and the limited electricity budget. We can pretend that “a large enough number of cells” is good enough; it often is. And it turns out any one Turing machine can be used to simulate another Turing machine. This requires us to not care about how long it takes to do something, but that’s all right. Conceptually, we don’t care.

    And I specifically got wondering what was the first pinball machine to be a Turing machine. I’m sure that modern pinball machines are, since there have been computers of some kind in pinball machines since the mid-1970s. So that’s a boring question. My question is: were there earlier pinball machines that satisfy the requirements of a Turing machine?

    My gut tells me there must be. This is mostly because it’s surprisingly hard not to create a Turing machine. If you hang around near mathematics or computer science people you’ll occasionally run across things like where someone created a computer inside a game like Minecraft. It’s possible to create a Turing machine using the elements of the game. The number of things that are Turing-complete, as they say, is surprising. CSS version 3, a rule system for how to dress up content on a web site, turns out to be Turing-complete (if you make some reasonable extra suppositions). Magic: The Gathering cards are, too. So you could set up a game of Magic: the Gathering which simulated a game of Minecraft which itself simulated the styling rules of a web page. Note the “you” in that sentence.

    That’s not proof, though. But I feel pretty good about supposing that some must be. Pinball machines consist, at heart, of a bunch of switches which are activated or not by whether a ball rolls over them. They can store a bit of information: a ball can be locked in a scoop, or kicked out of the scoop as need be. Points can be tallied on the scoring reel. The number of balls a player gets to plunge can be increased — or decreased — based on things that happen on the playfield. This feels to me like it’s got to be a Turing-complete scheme.

    So I suspect that the layout of a pinball game, and the various ways to store a bit of information, with (presumably) perfect ball-flipping and table-nudging skills, should make it possible to make a Turing machine. (There ought not be a human in the loop, but I’m supposing that we could replace the person with a mechanism that flips or nudges at the right times or when the ball is in the right place.) I’m wanting for proof, though, and I leave the question here to tease people who’re better than I am at this field of mathematics and computer science.

    And I’m curious when the first game that was so capable was made. The very earliest games were like large tabletop versions of those disappointing car toys, the tiny transparent-plastic things with a ball bearing you shoot into one of a series of scoops. Eventually, tilt mechanisms were added, and scoring reels, and then flippers, and then the chance to lock balls. Each changed what the games could do. Did it reach the level of complexity I think it did? I’d like to know.

    Yes, this means that I believe it would be theoretically possible to play a pinball game that itself simulated the Pinball Arcade program simulating another pinball game. If this prospect does not delight you then I do not know that we can hope to ever understand one another.

    • John Friedrich 12:15 am on Saturday, 25 March, 2017 Permalink | Reply

      I’m still struggling with the possibility that the entire universe is a computer simulation. No one has come up with a compelling argument against it yet.


      • Joseph Nebus 10:52 pm on Thursday, 30 March, 2017 Permalink | Reply

        I’m getting pretty far outside my competence to talk about a problem like that. It really calls on the expertise of the philosophy community to work out well.

        My poorly-considered thoughts about it run along these lines, though. Suppose our universe is a simulation run for whatever purpose in the super-universe. If there is no possible way for us to detect the super-universe’s existence, or to demonstrate that it is affecting our universe, then it’s hard to see what the difference is between the status of the simulated universe and whatever the universe being real might mean.

        But suppose that there is a super-universe. Then it’s hard to see what arguments for our universe being a simulation would not also apply to our super-universe; why shouldn’t it be a simulation in a super-super-universe? But then why wouldn’t that be a simulation in a super-super-super-universe? And so on to an infinite regression of universes simulated within more computationally powerful universes.

        That’s nothing conclusive, certainly. There’s no reason we can’t have an infinite regression like that. It feels wasteful of existence, somehow. But it also suggests there’s no point at which any entity in any of the super-(etc)-universes could be confident they were in reality. So either the infinite stack of simulations is wrong or there’s no such thing as “real”. Neither seems quite satisfying.

        I expect the professionals have better reasoning than mine, though. And it might be something that produces useful insights even if it can’t be resolved, akin to Zeno’s Paradoxes.


    • fluffy 5:47 pm on Saturday, 25 March, 2017 Permalink | Reply

      The thing with all those provable Turing machines is that they have dynamic and conceptually-unbounded amounts of storage space (Minecraft levels grow, Magic decks grow, etc.), whereas purely-mechanical pinball machines only have a finite amount of state. Which is to say that they are at best a finite state machine. I mean unless you want to go down the rabbit hole of considering every possible physical position of the ball to be a different state, in which case all you need for a Turing machine (given perfect nudge mechanics etc.) is a ball.


      • Joseph Nebus 10:59 pm on Thursday, 30 March, 2017 Permalink | Reply

        This is true, although I take a forgiving view of storage space. If we can imagine a Magic deck growing as large as needed for the problem we’re working, why can’t we imagine a Pop-A-Card that has a six- or seven- or even 10100-digit score reel? (Taking the score reel to be how the state is stored.) At least it seems to me if someone can keep getting all this tape for their classical Turing machine then we can hook another reel up.


  • Joseph Nebus 6:00 pm on Sunday, 19 March, 2017 Permalink | Reply
    Tags: 2 Cows And A Chicken, , , Arlo and Janis, , , Off The Mark, , , , Working Daze   

    Reading the Comics, March 18, 2017: Pi Day Edition 

    No surprise what the recurring theme for this set of mathematics-mentioning comic strips is. Look at the date range. But here goes.

    Henry Scarpelli and Craig Boldman’s Archie rerun for the 13th uses algebra as the thing that will stun a class into silence. I know the silence. As a grad student you get whole minutes of instructions on how to teach a course before being sent out as recitation section leader for some professor. And what you do get told is the importance of asking students their thoughts and their ideas. This maybe works in courses that are obviously friendly to opinions or partially formed ideas. But in Freshman Calculus? It’s just deadly. Even if you can draw someone into offering an idea how we might start calculating a limit (say), they’re either going to be exactly right or they’re going to need a lot of help coaxing the idea into something usable. I’d like to have more chatty classes, but some subjects are just hard to chat about.

    Mr Weatherby walks past a silent class. 'What a well-behaved class! ... Flutesnoot, how do you get them to be so quiet and still?' 'I just asked for a volunteer to solve an algebra problem!'

    Henry Scarpelli and Craig Boldman’s Archie rerun for the 13th of March, 2017. I didn’t know the mathematics teacher’s name and suppose that “Flutesnoot” is as plausible as anything. Anyway, I admire his ability to stand in front of a dead-silent class. The stage fright the scenario produces is powerful. At least when I was taught how to teach we got nothing about stage presence or how to remain confident during awkward pauses. What I know I learned from a half-year Drama course in high school.

    Steve Skelton’s 2 Cows And A Chicken for the 13th includes some casual talk about probability. As normally happens, they figure the chances are about 50-50. I think that’s a default estimate of the probability of something. If you have no evidence to suppose one outcome is more likely than the other, then that is a reason to suppose the chance of something is 50 percent. This is the Bayesian approach to probability, in which we rate things as more or less likely based on what information we have about how often they turn out. It’s a practical way of saying what we mean by the probability of something. It’s terrible if we don’t have much reliable information, though. We need to fall back on reasoning about what is likely and what is not to save us in that case.

    Scott Hilburn’s The Argyle Sweater lead off the Pi Day jokes with an anthropomorphic numerals panel. This is because I read most of the daily comics in alphabetical order by title. It is also because The Argyle Sweater is The Argyle Sweater. Among π’s famous traits is that it goes on forever, in decimal representations, yes. That’s not by itself extraordinary; dull numbers like one-third do that too. (Arguably, even a number like ‘2’ does, if you write all the zeroes in past the decimal point.) π gets to be interesting because it goes on forever without repeating, and without having a pattern easily describable. Also because it’s probably a normal number but we don’t actually know that for sure yet.

    Mark Parisi’s Off The Mark panel for the 14th is another anthropomorphic numerals joke and nearly the same joke as above. The answer, dear numeral, is “chained tweets”. I do not know that there’s a Twitter bot posting the digits of π in an enormous chained Twitter feed. But there’s a Twitter bot posting the digits of π in an enormous chained Twitter feed. If there isn’t, there is now.

    John Zakour and Scott Roberts’s Working Daze for the 14th is your basic Pi Day Wordplay panel. I think there were a few more along these lines but I didn’t record all of them. This strip will serve for them all, since it’s drawn from an appealing camera angle to give the joke life.

    Dave Blazek’s Loose Parts for the 14th is a mathematics wordplay panel but it hasn’t got anything to do with π. I suspect he lost track of what days he was working on, back six or so weeks when his deadline arrived.

    Keith Tutt and Daniel Saunders’s Lard’s World Peace Tips for the 15th is some sort of joke about the probability of the world being like what it seems to be. I’m not sure precisely what anyone is hoping to express here or how it ties in to world peace. But the world does seem to be extremely well described by techniques that suppose it to be random and unpredictable in detail. It is extremely well predictable in the main, which shows something weird about the workings of the world. It seems to be doing all right for itself.

    Zach Weinersmith’s Saturday Morning Breakfast Cereal for the 15th is built on the staggering idea that the Earth might be the only place with life in the universe. The cosmos is a good stand-in for infinitely large things. It might be better as a way to understand the infinitely large than actual infinity would be. Somehow thinking of the number of stars (or whatnot) in the universe and writing out a representable number inspires an understanding for bigness that the word “infinity” or the symbols we have for it somehow don’t seem to, at least to me.

    Mikael Wulff and Anders Morgenthaler’s TruthFacts for the 17th gives us valuable information about how long ahead of time the comic strips are working. Arithmetic is probably the easiest thing to use if one needs an example of a fact. But even “2 + 2 = 4” is a fact only if we accept certain ideas about what we mean by “2” and “+” and “=” and “4”. That we use those definitions instead of others is a reflection of what we find interesting or useful or attractive. There is cultural artifice behind the labelling of this equation as a fact.

    Jimmy Johnson’s Arlo and Janis for the 18th capped off a week of trying to explain some point about the compression and dilution of time in comic strips. Comic strips use space and time to suggest more complete stories than they actually tell. They’re much like every other medium in this way. So, to symbolize deep thinking on a subject we get once again a panel full of mathematics. Yes, I noticed the misquoting of “E = mc2” there. I am not sure what Arlo means by “Remember the boat?” although thinking on it I think he did have a running daydream about living on a boat. Arlo and Janis isn’t a strongly story-driven comic strip, but Johnson is comfortable letting the setting evolve. Perhaps all this is forewarning that we’re going to jump ahead to a time in Arlo’s life when he has, or has had, a boat. I don’t know.

  • Joseph Nebus 6:00 pm on Saturday, 18 March, 2017 Permalink | Reply
    Tags: , , , , , ,   

    How Interesting Is March Madness? 

    And now let me close the week with some other evergreen articles. A couple years back I mixed the NCAA men’s basketball tournament with information theory to produce a series of essays that fit the title I’ve given this recap. They also sprawl out into (US) football and baseball. Let me link you to them:

  • Joseph Nebus 6:00 pm on Thursday, 16 March, 2017 Permalink | Reply
    Tags: , , , Dustin, , Red and Rover, , weddings   

    Reading the Comics, March 11, 2017: Accountants Edition 

    And now I can wrap up last week’s delivery from Comic Strip Master Command. It’s only five strips. One certainly stars an accountant. one stars a kid that I believe is being coded to read as an accountant. The rest, I don’t know. I pick Edition titles for flimsy reasons anyway. This’ll do.

    Ryan North’s Dinosaur Comics for the 6th is about things that could go wrong. And every molecule of air zipping away from you at once is something which might possibly happen but which is indeed astronomically unlikely. This has been the stuff of nightmares since the late 19th century made probability an important part of physics. The chance all the air near you would zip away at once is impossibly unlikely. But such unlikely events challenge our intuitions about probability. An event that has zero chance of happening might still happen, given enough time and enough opportunities. But we’re not using our time well to worry about that. If nothing else, even if all the air around you did rush away at once, it would almost certainly rush back right away.

    'The new SAT multiple-choice questions have 4 answers instead of 5, with no penalty for guessing.' 'Let's see ... so if I took it now ... that would be one chance in four, which would be ... 25%?' 'Yes.' 'But back when I took it, my chances were ... let's see ... um ...' 'Remember, there's no penalty for guessing.'

    Steve Kelley and Jeff Parker’s Dustin for the 7th of March, 2017. It’s the title character doing the guessing there. Also, Kelley and Parker hate their title character with a thoroughness you rarely see outside Tom Batiuk and Funky Winkerbean. This is a mild case of it but, there we are.

    Steve Kelley and Jeff Parker’s Dustin for the 7th of March talks about the SATs and the chance of picking right answers on a multiple-choice test. I haven’t heard about changes to the SAT but I’ll accept what the comic strip says about them for the purpose of discussion here. At least back when I took it the SAT awarded one point to the raw score for a correct answer, and subtracted one-quarter point for a wrong answer. (The raw scores were then converted into a 200-to-800 range.) I liked this. If you had no idea and guessed on answers you should expect to get one in five right and four in five wrong. On average then you would expect no net change to your raw score. If one or two wrong answers can be definitely ruled out then guessing from the remainder brings you a net positive. I suppose the change, if it is being done, is meant to be confident only right answers are rewarded. I’m not sure this is right; it seems to me there’s value in being able to identify certainly wrong answers even if the right one isn’t obvious. But it’s not my test and I don’t expect to need to take it again either. I can expression opinions without penalty.

    Mark Anderson’s Andertoons for the 7th is the Mark Anderson’s Andertoons for last week. It’s another kid-at-the-chalkboard panel. What gets me is that if the kid did keep one for himself then shouldn’t he have written 38?

    Brian Basset’s Red and Rover for the 8th mentions fractions. It’s just there as the sort of thing a kid doesn’t find all that naturally compelling. That’s all right I like the bug-eyed squirrel in the first panel.

    'The happy couple is about to cut the cake!' 'What kind is it?' 'A math cake.' (It has a square root of 4 sign atop it.)

    Bill Holbrook’s On The Fastrack for the 9th of March, 2017. I confess I’m surprised Holbrook didn’t think to set the climax a couple of days later and tie it in to Pi Day.

    Bill Holbrook’s On The Fastrack for the 9th concludes the wedding of accountant Fi. It uses the square root symbol so as to make the cake topper clearly mathematical as opposed to just an age.

  • Joseph Nebus 6:00 pm on Tuesday, 14 March, 2017 Permalink | Reply
    Tags: , ,   

    Terrible and Less-Terrible Pi 

    As the 14th of March comes around it’s the time for mathematics bloggers to put up whatever they can about π. I will stir from my traditional crankiness about Pi Day (look, we don’t write days of the year as 3.14 unless we’re doing fake stardates) to bring back my two most π-relevant posts:

    • Calculating Pi Terribly is about a probability-based way to calculate just what π’s digits are. It’s a lousy way to do it, but it works, technically.
    • Calculating Pi Less Terribly is about an analysis-based way to calculate just what π’s digits are. It’s a less bad way to do it, although we actually use better-yet ways to work out the digits of a number like this.
    • And what the heck, Normal Numbers, from an A To Z sequence. We do not actually know that π is a normal number. It’s the way I would bet, though, and here’s something about why I’d bet that way.
  • Joseph Nebus 6:00 pm on Sunday, 12 March, 2017 Permalink | Reply
    Tags: , Basic Instructions, , Little Iodine, Phoebe and her Unicorn, Piranha Club,   

    Reading the Comics, March 6, 2017: Blackboards Edition 

    I can’t say there’s a compelling theme to the first five mathematically-themed comics of last week. Screens full of mathematics turned up in a couple of them, so I’ll run with that. There were also just enough strips that I’m splitting the week again. It seems fair to me and gives me something to remember Wednesday night that I have to rush to complete.

    Jimmy Hatlo’s Little Iodine for the 1st of January, 1956 was rerun on the 5th of March. The setup demands Little Iodine pester her father for help with the “hard homework” and of course it’s arithmetic that gets to play hard work. It’s a word problem in terms of who has how many apples, as you might figure. Don’t worry about Iodine’s boss getting fired; Little Iodine gets her father fired every week. It’s their schtick.

    Little Iodine wakes her father early after a night at the lodge. 'You got to help me with my [hard] homework.' 'Ooh! My head! Wha'?' 'The first one is, if John has twice as many apples as Tom and Sue put together ... ' 'Huh? kay! Go on, let's get this over with.' They work through to morning. Iodine's teacher sees her asleep in class and demands she bring 'a note from your parents as to why you sleep in school instead of at home!' She goes to her father's office where her father's boss is saying, 'Well, Tremblechin, wake up! The hobo hotel is three blocks south and PS: DON'T COME BACK!'

    Jimmy Hatlo’s Little Iodine for the 1st of January, 1956. I guess class started right back up the 2nd, but it would’ve avoided so much trouble if she’d done her homework sometime during the winter break. That said, I never did.

    Dana Simpson’s Phoebe and her Unicorn for the 5th mentions the “most remarkable of unicorn confections”, a sugar dodecahedron. Dodecahedrons have long captured human imaginations, as one of the Platonic Solids. The Platonic Solids are one of the ways we can make a solid-geometry analogue to a regular polygon. Phoebe’s other mentioned shape of cubes is another of the Platonic Solids, but that one’s common enough to encourage no sense of mystery or wonder. The cube’s the only one of the Platonic Solids that will fill space, though, that you can put into stacks that don’t leave gaps between them. Sugar cubes, Wikipedia tells me, have been made only since the 19th century; the Moravian sugar factory director Jakub Kryštof Rad got a patent for cutting block sugar into uniform pieces in 1843. I can’t dispute the fun of “dodecahedron” as a word to say. Many solid-geometric shapes have names that are merely descriptive, but which are rendered with Greek or Latin syllables so as to sound magical.

    Bud Grace’s Piranha Club for the 6th started a sequence in which the Future Disgraced Former President needs the most brilliant person in the world, Bud Grace. A word balloon full of mathematics is used as symbol for this genius. I feel compelled to point out Bud Grace was a physics major. But while Grace could as easily have used something from the physics department to show his deep thinking abilities, that would all but certainly have been rendered as equation and graphs, the stuff of mathematics again.

    At the White Supremacist House: 'I have the smartest people I could find to help me run this soon-to-be-great-again country, but I'm worried that they're NOT SMART ENOUGH! I want the WORLD'S SMARTEST GENIUS to be my SPECIAL ADVISOR!' Meanwhile, cartoonist Bud Grace thinks of stuff like A = pi*r^2 and a^2 + b^2 = c^2 and tries working out 241 times 365, 'carry the one ... hmmmm ... '

    Bud Grace’s Piranha Club for the 6th of March, 2017. 241 times 635 is 153,035 by the way. I wouldn’t work that out in my head if I needed the number. I might work out an estimate of how big it was, in which case I’d do this: 241 is about 250, which is one-quarter of a thousand. One-quarter of 635 is something like 150, which times a thousand is 150,000. If I needed it exactly I’d get a calculator. Unless I just needed something to occupy my mind without having any particular emotional charge.

    Scott Meyer’s Basic Instructions rerun for the 6th is aptly titled, “How To Unify Newtonian Physics And Quantum Mechanics”. Meyer’s advice is not bad, really, although generic enough it applies to any attempts to reconcile two different models of a phenomenon. Also there’s not particularly a problem reconciling Newtonian physics with quantum mechanics. It’s general relativity and quantum mechanics that are so hard to reconcile.

    Still, Basic Instructions is about how you can do a thing, or learn to do a thing. It’s not about how to allow anything to be done for the first time. And it’s true that, per quantum mechanics, we can’t predict exactly what any one particle will do at any time. We can say what possible things it might do and how relatively probable they are. But big stuff, the stuff for which Newtonian physics is relevant, involve so many particles that the unpredictability becomes too small to notice. We can see this as the Law of Large Numbers. That’s the probability rule that tells us we can’t predict any coin flip, but we know that a million fair tosses of a coin will not turn up 800,000 tails. There’s more to it than that (there’s always more to it), but that’s a starting point.

    Michael Fry’s Committed rerun for the 6th features Albert Einstein as the icon of genius. Natural enough. And it reinforces this with the blackboard full of mathematics. I’m not sure if that blackboard note of “E = md3” is supposed to be a reference to the famous Far Side panel of Einstein hearing the maid talk about everything being squared away. I’ll take it as such.

  • Joseph Nebus 6:00 pm on Thursday, 9 March, 2017 Permalink | Reply
    Tags: , ,   

    Words About A Wordless Induction Proof 

    This pair of tweets came across my feed. And who doesn’t like a good visual proof of a mathematical fact? I hope you enjoy.

    So here’s the proposition.

    This is the sort of identity we normally try proving by induction. Induction is a great scheme for proving identities like this. It works by finding some index on the formula. Then show that if the formula is true for one value of the index, then it’s true for the next-higher value of the index. Finally, find some value of the index for which it’s easy to check that the formula’s true. And that proves it’s true for all the values of that index above that base.

    In this case the index is ‘n’. It’s really easy to prove the base case, since 13 is equal to 12 what with ‘1’ being the number everybody likes to raise to powers. Going from proving that if it’s true in one case — 1^3 + 2^3 + 3^3 + \cdots + n^3 — then it’s true for the next — 1^3 + 2^3 + 3^3 + \cdots + n^3 + (n + 1)^3 — is work. But you can get it done.

    And then there’s this, done visually:

    It took me a bit to read fully until I was confident in what it was showing. But it is all there.

    As often happens with these wordless proofs you can ask whether it is properly speaking a proof. A proof is an argument and to be complete it has to contain every step needed to deduce the conclusion from the premises, following one of the rules of inference each step. Thing is basically no proof is complete that way, because it takes forever. We elide stuff that seems obvious, confident that if we had to we could fill in the intermediate steps. A wordless proof like trusts that if we try to describe what is in the picture then we are constructing the argument.

    That’s surely enough of my words.

  • Joseph Nebus 6:00 pm on Tuesday, 7 March, 2017 Permalink | Reply
    Tags: , , , ,   

    How February 2017 Treated My Mathematics Blog 

    It was another pretty busy month around these parts. According to WordPress’s statistics page there were 1,063 page views from 680 unique visitors. That’s slightly up from January’s 1,031 page views and 586 unique visitors, and pretty substantially up from December 2016’s 956 page views an 589 unique visitors. And that for what was a pretty easy month of writing. Most of my posts were Reading the Comics essays, for which I don’t have to think about what to write. I just have to write it. That’s way easier.

    If it was one of the most popular months I’ve had i a while, it was also one of the least popular months I’ve had in a while. There were only 77 posts given ‘likes’ in February, compared to 97 in January and 136 in December. Indeed, this was the lowest number of likes in a month in the past two years. Comments were down too, to 18, the lowest count since August 2016. January had had 34 comments and December 29. The Reading the Comics posts don’t give a lot to discuss, I suppose.

    According to the Insights tab, the most popular day for reading was Monday, with 16 percent of page views. In January it had ben Thursdays, also with 16 percent of page views; in December it was Sundays. Sunday makes sense because that’s when Reading the Comics post go up. Monday? I don’t know.

    The most popular hour was 6:00 pm, which got 11 percent of page views. The hour’s stayed consistent for the last several months, although in January it saw only 10 percent of page views. 6:00 pm Universal Time is when I put up most of my posts, so that makes sense.

    There were 64 countries in this month’s roster of country views, up from January’s 53. 22 of them were single-viewer countries, up from 13 too. My “European Union” audience is back and in force.

    Country Views
    United States 544
    United Kingdom 84
    India 52
    Canada 40
    Hong Kong SAR China 27
    Singapore 26
    Philippines 25
    Germany 19
    Puerto Rico 19
    Australia 16
    Brazil 13
    France 13
    US Virgin Islands 12
    Netherlands 10
    Slovenia 9
    Israel 8
    Thailand 8
    Czech Republic 5
    Spain 5
    Sweden 5
    Switzerland 5
    Croatia 4
    Italy 4
    New Zealand 4
    Oman 4
    South Africa 4
    Argentina 3
    Austria 3
    Belgium 3
    Colombia 3
    European Union 3
    Greece 3
    Jamaica 3
    Poland 3
    Bulgaria 2
    Denmark 2
    Estonia 2
    Finland 2
    Indonesia 2
    Mexico 2
    Morocco 2
    Ukraine 2
    Albania 1
    Algeria 1
    Armenia 1
    Bahrain 1
    Bermuda 1
    Cyprus 1
    Hungary 1
    Ireland 1
    Japan 1
    Luxembourg 1
    Macedonia 1
    Nepal 1
    Norway 1
    Romania 1
    Saudi Arabia 1
    South Korea 1 (*)
    Sri Lanka 1
    Taiwan 1
    Uganda 1
    United Arab Emirates 1
    Venezuela 1
    Vietnam 1

    South Korea is the only country that was single-reader two months in a row. I think that’s the closest to a complete turnover I’ve gotten since I started tracking this.

    The most popular posts this month were three of the Immortals and then one that just captured people’s imagination:

    Clearly I need to do more how-to mathematics posts.

    Among the search terms bringing people here:

    • what do you think would a trapezoid look like we rotate it by quarter-turn?
    • comic strip about statistics and probability
    • comic strip about velocity and scalar
    • origin is the gateway to your entire gaming universe
    • comics about gay-lussac law
    • comics about liquefaction
    • comics of pythagoras ideas about model of the universe

    I hesitate to swipe Math With Bad Drawings’ schtick, but this does suggest I ought to be commissioning some comic strips for here.

    WordPress thinks I started the month with 642 followers on WordPress. You can be among them by using the link in the upper-right corner of this theme. There’s also the chance to follow by e-mail, which a couple of people do. The advantage of following by e-mail is you get the blog by e-mail, so that I don’t have the chance to fix typos and clumsy word choices before you can see it. And I’m on Twitter, as @nebusj, if you want to see that. You get some hints of it from one of the panels on the right.

    March 2017 starts with my page here having got 46,198 views from something like 20,155 recorded unique visitors. (The blog started before WordPress counted unique visitors in any way they tell us about.) So my humor blog’s overtaken this one in both counts, but that’s all right. I post more stuff over there.

  • Joseph Nebus 6:00 pm on Sunday, 5 March, 2017 Permalink | Reply
    Tags: , , , Luann Againn, , , Poor Richard's Almanac, ,   

    Reading the Comics, March 4, 2017: Frazz, Christmas Trees, and Weddings Edition 

    It was another of those curious weeks when Comic Strip Master Command didn’t send quite enough comics my way. Among those they did send were a couple of strips in pairs. I can work with that.

    Samson’s Dark Side Of The Horse for the 26th is the Roman Numerals joke for this essay. I apologize to Horace for being so late in writing about Roman Numerals but I did have to wait for Cecil Adams to publish first.

    In Jef Mallett’s Frazz for the 26th Caulfield ponders what we know about Pythagoras. It’s hard to say much about the historical figure: he built a cult that sounds outright daft around himself. But it’s hard to say how much of their craziness was actually their craziness, how much was just that any ancient society had a lot of what seems nutty to us, and how much was jokes (or deliberate slander) directed against some weirdos. What does seem certain is that Pythagoras’s followers attributed many of their discoveries to him. And what’s certain is that the Pythagorean Theorem was known, at least a thing that could be used to measure things, long before Pythagoras was on the scene. I’m not sure if it was proved as a theorem or whether it was just known that making triangles with the right relative lengths meant you had a right triangle.

    Greg Evans’s Luann Againn for the 28th of February — reprinting the strip from the same day in 1989 — uses a bit of arithmetic as generic homework. It’s an interesting change of pace that the mathematics homework is what keeps one from sleep. I don’t blame Luann or Puddles for not being very interested in this, though. Those sorts of complicated-fraction-manipulation problems, at least when I was in middle school, were always slogs of shuffling stuff around. They rarely got to anything we’d like to know.

    Jef Mallett’s Frazz for the 1st of March is one of those little revelations that statistics can give one. Myself, I was always haunted by the line in Carl Sagan’s Cosmos about how, in the future, with the Sun ageing and (presumably) swelling in size and heat, the Earth would see one last perfect day. That there would most likely be quite fine days after that didn’t matter, and that different people might disagree on what made a day perfect didn’t matter. Setting out the idea of a “perfect day” and realizing there would someday be a last gave me chills. It still does.

    Richard Thompson’s Poor Richard’s Almanac for the 1st and the 2nd of March have appeared here before. But I like the strip so I’ll reuse them too. They’re from the strip’s guide to types of Christmas trees. The Cubist Fur is described as “so asymmetrical it no longer inhabits Euclidean space”. Properly neither do we, but we can’t tell by eye the difference between our space and a Euclidean space. “Non-Euclidean” has picked up connotations of being so bizarre or even horrifying that we can’t hope to understand it. In practice, it means we have to go a little slower and think about, like, what would it look like if we drew a triangle on a ball instead of a sheet of paper. The Platonic Fir, in the 2nd of March strip, looks like a geometry diagram and I doubt that’s coincidental. It’s very hard to avoid thoughts of Platonic Ideals when one does any mathematics with a diagram. We know our drawings aren’t very good triangles or squares or circles especially. And three-dimensional shapes are worse, as see every ellipsoid ever done on a chalkboard. But we know what we mean by them. And then we can get into a good argument about what we mean by saying “this mathematical construct exists”.

    Mark Litzler’s Joe Vanilla for the 3rd uses a chalkboard full of mathematics to represent the deep thinking behind a silly little thing. I can’t make any of the symbols out to mean anything specific, but I do like the way it looks. It’s quite well-done in looking like the shorthand that, especially, physicists would use while roughing out a problem. That there are subscripts with forms like “12” and “22” with a bar over them reinforces that. I would, knowing nothing else, expect this to represent some interaction between particles 1 and 2, and 2 with itself, and that the bar means some kind of complement. This doesn’t mean much to me, but with luck, it means enough to the scientist working it out that it could be turned into a coherent paper.

    'Has Carl given you any reason not to trust him?' 'No, not yet. But he might.' 'Fi ... you seek 100% certainty in people, but that doesn't exist. In the end,' and Dethany is drawn as her face on a pi symbol, 'we're *all* irrational numbers.'

    Bill Holbrook’s On The Fastrack for the 3rd of March, 2017. Fi’s dress isn’t one of those … kinds with the complicated pattern of holes in it. She got it torn while trying to escape the wedding and falling into the basement.

    Bill Holbrook’s On The Fastrack is this week about the wedding of the accounting-minded Fi. And she’s having last-minute doubts, which is why the strip of the 3rd brings in irrational and anthropomorphized numerals. π gets called in to serve as emblematic of the irrational numbers. Can’t fault that. I think the only more famously irrational number is the square root of two, and π anthropomorphizes more easily. Well, you can draw an established character’s face onto π. The square root of 2 is, necessarily, at least two disconnected symbols and you don’t want to raise distracting questions about whether the root sign or the 2 gets the face.

    That said, it’s a lot easier to prove that the square root of 2 is irrational. Even the Pythagoreans knew it, and a bright child can follow the proof. A really bright child could create a proof of it. To prove that π is irrational is not at all easy; it took mathematicians until the 19th century. And the best proof I know of the fact does it by a roundabout method. We prove that if a number (other than zero) is rational then the tangent of that number must be irrational, and vice-versa. And the tangent of π/4 is 1, so therefore π/4 must be irrational, so therefore π must be irrational. I know you’ll all trust me on that argument, but I wouldn’t want to sell it to a bright child.

    'Fi ... humans are complicated. Like the irrational number pi, we can go on forever. You never get to the bottom of us! But right now, upstairs, there are two variables who *want* you in their lives. Assign values to them.' Carl, Fi's fiancee, is drawn as his face with a y; his kid as a face on an x.

    Bill Holbrook’s On The Fastrack for the 4th of March, 2017. I feel bad that I completely forgot Carl had a kid and that the face on the x doesn’t help me remember anything.

    Holbrook continues the thread on the 4th, extends the anthropomorphic-mathematics-stuff to call people variables. There’s ways that this is fair. We use a variable for a number whose value we don’t know or don’t care about. A “random variable” is one that could take on any of a set of values. We don’t know which one it does, in any particular case. But we do know — or we can find out — how likely each of the possible values is. We can use this to understand the behavior of systems even if we never actually know what any one of it does. You see how I’m going to defend this metaphor, then, especially if we allow that what people are likely or unlikely to do will depend on context and evolve in time.

  • Joseph Nebus 6:00 pm on Friday, 3 March, 2017 Permalink | Reply
    Tags: , , The Straight Dope   

    How To Use Roman Numerals (A Not Quite Useful Guide) 

    I haven’t got the chance to write a proper essay today, but did want to be sure people didn’t miss The Straight Dope this week. Cecil Adams gets the question “How did anyone do math in Roman numerals?” and does what he can to answer in a couple hundred words of newspaper space.

    It’ll disappoint you if you have visions of whipping through a quadratic equation written all in V’s and L’s and stuff. Roman numeral arithmetic is really easy for addition and subtraction. Multiplication and division turn into real challenges for which you need mechanical aid and the abacus. Adams describes this loosely, although not in enough detail that you’ll come away confident with your abacus. Fair enough. I’ve got a charming little abacus myself, someone’s gift to me, and I can’t use it even to the slight extent I can use a slide rule.

    The important thing, though, is that as a young know-it-all Cecil Adams’s first two books, The Straight Dope and The Return of the Straight Dope, were just magnificently important reading. Not as hefty as David Wallechinsky and Irving Wallace’s The People’s Almanac 2, but with a much higher fascinating-stuff-to-boring-stuff ratio. Stuff on Oak Island’s Treasure Pit and the (former) names of New York City boroughs and the like. I’m glad it’s still there.

    • Biff Sock Pow 10:16 pm on Friday, 3 March, 2017 Permalink | Reply

      Great post! I used to enjoy The Straight Dope when I first moved to Dallas in the 1980s. I want to say he was printed in the Dallas Observer, along with another literary titan of the time, Joe Bob Briggs (back when he just wrote spot-on movie reviews and wry observations about the local scene). But many of those brain cells from way back then are deceased, and so I could be misremembering the whole thing. Also, I still have my copy of The People’s Almanac (Roman numeral uno) that I purchased brand-spanking new back in 1975 or so. As a youth with lots of time on my hands, I read it cover to cover (all 1446 pages of it), slowing down in the more prurient parts, of course. It was an awesome book! Thanks for the trip down memory lane! Made me feel like I was XVI again.

      Liked by 1 person

      • Joseph Nebus 4:55 am on Saturday, 11 March, 2017 Permalink | Reply

        I’m glad hearing all this. I never saw The Straight Dope in newspapers, just in the book forms, tucked into the fascinating-miscellaneous books section of the library. And so read it a lot, over and over. The People’s Almanac 2 was one that my family had for some reason or other. We never had Almanac 1, and I never saw a copy. In college the newspaper office did briefly have a copy of The People’s Almanac 3 but I didn’t get the chance to absorb that nearly so well.

        Liked by 1 person

  • Joseph Nebus 6:00 pm on Tuesday, 28 February, 2017 Permalink | Reply
    Tags: , , , Julian Dates, , , US Naval Observatory   

    How To Work Out The Length Of Time Between Two Dates 

    September 1999 was a heck of a month you maybe remember. There that all that excitement of the Moon being blasted out of orbit thanks to the nuclear waste pile up there getting tipped over or something. And that was just as we were getting over the final new episode of Mystery Science Theater 3000‘s first airing. That episode was number 1003, Merlin’s Shop of Mystical Wonders, which aired a month after the season finale because of one of those broadcast rights tangles that the show always suffered through.

    Time moves on, and strange things happen, and show co-creator and first host Joel Hodgson got together a Kickstarter and a Netflix deal. The show’s Season Eleven is supposed to air starting the 14th of April, this year. The natural question: how long will we go, then, between new episodes of Mystery Science Theater 3000? Or more generally, how do you work out how long it is between two dates?

    The answer is dear Lord under no circumstances try to work this out yourself. I’m sorry to be so firm. But the Gregorian calendar grew out of a bunch of different weird influences. It’s just hard to keep track of all the different 31- and 30-day months between two events. And then February is all sorts of extra complications. It’s especially tricky if the interval spans a century year, like 2000, since the majority of those are not leap years, except that the one century year I’m likely to experience was. And then if your interval happens to cross the time the local region switched from the Julian to the Gregorian calendar —

    So my answer is don’t ever try to work this out yourself. Never. Just refuse the problem if you’re given it. If you’re a consultant charge an extra hundred dollars for even hearing the problem.

    All right, but what if you really absolutely must know for some reason? I only know one good answer. Convert the start and the end dates of your interval into Julian Dates and subtract one from the other. I mean subtract the smaller number from the larger. Julian Dates are one of those extremely minor points of calendar use. They track the number of days elapsed since noon, Universal Time, on the Julian-calendar date we call the 1st of January, 4713 BC. The scheme, for years, was set up in 1583 by Joseph Justus Scalinger, calendar reformer, who wanted for convenience an index year so far back that every historically known event would have a positive number. In the 19th century the astronomer John Herschel expanded it to date-counting.

    Scalinger picked the year from the convergence of a couple of convenient calendar cycles about how the sun and moon move as well as the 15-year indiction cycle that the Roman Empire used for tax matters (and that left an impression on European nations). His reasons don’t much matter to us. The specific choice means we’re not quite three-fifths of the way through the days in the 2,400,000’s. So it’s not rare to modify the Julian Date by subtracting 2,400,000 from it. The date starts from noon because astronomers used to start their new day at noon, which was more convenient for logging a whole night’s observations. Since astronomers started taking pictures of stuff and looking at them later they’ve switched to the new day starting at midnight like everybody else, but you know what it’s like changing an old system.

    This summons the problem: so how do I know many dates passed between whatever day I’m interested in and the Julian Calendar 1st of January, 4713 BC? Yes, there’s a formula. No, don’t try to use it. Let the fine people at the United States Naval Observatory do the work for you. They know what they’re doing and they’ve had this calculator up for a very long time without any appreciable scandal accruing to it. The system asks you for a time of day, because the Julian Date increases as the day goes on. You can just make something up if the time doesn’t matter. I normally leave it on midnight myself.

    So. The last episode of Mystery Science Theater 3000 to debut, on the 12th of September, 1999, did so on Julian Date 2,451,433. (Well, at 9 am Eastern that day, but nobody cares about that fine grain a detail.) The new season’s to debut on Netflix the 14th of April, 2017, which will be Julian Date 2,457,857. (I have no idea if there’s a set hour or if it’ll just become available at 12:01 am in whatever time zone Netflix Master Command’s servers are in.) That’s a difference of 6,424 days. You’re on your own in arguing about whether that means it was 6,424 or 6,423 days between new episodes.

    If you do take anything away from this, though, please let it be the warning: never try to work out the interval between dates yourself.

    • elkement (Elke Stangl) 9:31 am on Friday, 3 March, 2017 Permalink | Reply

      And I figured the routine date and time conversion mess you face as a software developer is a challenge ;-) …


      • Joseph Nebus 4:53 am on Saturday, 11 March, 2017 Permalink | Reply

        Oh you have no idea. In that one ancient database was designed with every column a string, and dates entered as literally, eg, ’03/10/2017′. That string of text. Which was all right when the date just had to be shown on-screen but then I had said it should be easy to include a date range, unaware of just what was in the database. Also, that there are so many mistakes too. Or people entering 00/00/0000 when the date wasn’t available.

        Liked by 1 person

  • Joseph Nebus 6:00 pm on Sunday, 26 February, 2017 Permalink | Reply
    Tags: , , Flo and Friends, , , , Promises Promises, , , , Tiger   

    Reading the Comics, February 23, 2017: The Week At Once Edition 

    For the first time in ages there aren’t enough mathematically-themed comic strips to justify my cutting the week’s roundup in two. No, I have no idea what I’m going to write about for Thursday. Let’s find out together.

    Jenny Campbell’s Flo and Friends for the 19th faintly irritates me. Flo wants to make sure her granddaughter understands that just because it takes people on average 14 minutes to fall asleep doesn’t mean that anyone actually does, by listing all sorts of reasons that a person might need more than fourteen minutes to sleep. It makes me think of a behavior John Allen Paulos notes in Innumeracy, wherein the statistically wise points out that someone has, say, a one-in-a-hundred-million chance of being killed by a terrorist (or whatever) and is answered, “ah, but what if you’re that one?” That is, it’s a response that has the form of wisdom without the substance. I notice Flo doesn’t mention the many reasons someone might fall asleep in less than fourteen minutes.

    But there is something wise in there nevertheless. For most stuff, the average is the most common value. By “the average” I mean the arithmetic mean, because that is what anyone means by “the average” unless they’re being difficult. (Mathematicians acknowledge the existence of an average called the mode, which is the most common value (or values), and that’s most common by definition.) But just because something is the most common result does not mean that it must be common. Toss a coin fairly a hundred times and it’s most likely to come up tails 50 times. But you shouldn’t be surprised if it actually turns up tails 51 or 49 or 45 times. This doesn’t make 50 a poor estimate for the average number of times something will happen. It just means that it’s not a guarantee.

    Gary Wise and Lance Aldrich’s Real Life Adventures for the 19th shows off an unusually dynamic camera angle. It’s in service for a class of problem you get in freshman calculus: find the longest pole that can fit around a corner. Oh, a box-spring mattress up a stairwell is a little different, what with box-spring mattresses being three-dimensional objects. It’s the same kind of problem. I want to say the most astounding furniture-moving event I’ve ever seen was when I moved a fold-out couch down one and a half flights of stairs single-handed. But that overlooks the caged mouse we had one winter, who moved a Chinese finger-trap full of crinkle paper up the tight curved plastic to his nest by sheer determination. The trap was far longer than could possibly be curved around the tube. We have no idea how he managed it.

    J R Faulkner’s Promises, Promises for the 20th jokes that one could use Roman numerals to obscure calculations. So you could. Roman numerals are terrible things for doing arithmetic, at least past addition and subtraction. This is why accountants and mathematicians abandoned them pretty soon after learning there were alternatives.

    Mark Anderson’s Andertoons for the 21st is the Mark Anderson’s Andertoons for the week. Probably anything would do for the blackboard problem, but something geometry reads very well.

    Jef Mallett’s Frazz for the 21st makes some comedy out of the sort of arithmetic error we all make. It’s so easy to pair up, like, 7 and 3 make 10 and 8 and 2 make 10. It takes a moment, or experience, to realize 78 and 32 will not make 100. Forgive casual mistakes.

    Bud Fisher’s Mutt and Jeff rerun for the 22nd is a similar-in-tone joke built on arithmetic errors. It’s got the form of vaudeville-style sketch compressed way down, which is probably why the third panel could be made into a satisfying final panel too.

    'How did you do on the math test?' 'Terrible.' 'Will your mom be mad?' 'Maybe. But at least she'll know I didn't cheat!'

    Bud Blake’s Tiger for the 23rd of February, 2017. I want to blame the colorists for making Hugo’s baby tooth look so weird in the second and third panels, but the coloring is such a faint thing at that point I can’t. I’m sorry to bring it to your attention if you didn’t notice and weren’t bothered by it before.

    Bud Blake’s Tiger rerun for the 23rd just name-drops mathematics; it could be any subject. But I need some kind of picture around here, don’t I?

    Mike Baldwin’s Cornered for the 23rd is the anthropomorphic numerals joke for the week.

  • Joseph Nebus 6:00 pm on Thursday, 23 February, 2017 Permalink | Reply
    Tags: , , compulsions, , Over The Hedge, , , Wide Open   

    Reading the Comics, February 15, 2017: SMBC Does Not Cut In Line Edition 

    On reflection, that Saturday Morning Breakfast Cereal I was thinking about was not mathematically-inclined enough to be worth including here. Helping make my mind up on that was that I had enough other comic strips to discuss here that I didn’t need to pad my essay. Yes, on a slow week I let even more marginal stuff in. Here’s the comic I don’t figure to talk about. Enjoy!

    Jack Pullan’s Boomerangs rerun for the 16th is another strip built around the “algebra is useless in real life” notion. I’m too busy noticing Mom in the first panel saying “what are you doing play [sic] video games?” to respond.

    Ruben Bolling’s Super-Fun-Pak Comix excerpt for the 16th is marginal, yeah, but fun. Numeric coincidence and numerology can sneak into compulsions with terrible ease. I can believe easily the need to make the number of steps divisible by some favored number.

    Rich Powell’s Wide Open for the 16th is a caveman science joke, and it does rely on a chalkboard full of algebra for flavor. The symbols come tantalizingly close to meaningful. The amount of kinetic energy, K or KE, of a particle of mass m moving at speed v is indeed K = \frac{1}{2} m v^2 . Both 16 and 32 turn up often in the physics of falling bodies, at least if we’re using feet to measure. a = -\frac{k}{m} x turns up in physics too. It comes from the acceleration of a mass on a spring. But an equation of the same shape turns up whenever you describe things that go through tiny wobbles around the normal value. So the blackboard is gibberish, but it’s a higher grade of gibberish than usual.

    Rick Detorie’s One Big Happy rerun for the 17th is a resisting-the-word-problem joke, made fresher by setting it in little Ruthie’s playing at school.

    T Lewis and Michael Fry’s Over The Hedge for the 18th mentions the three-body problem. As Verne the turtle says, it’s a problem from physics. The way two objects — sun and planet, planet and moon, pair of planets, whatever — orbit each other if they’re the only things in the universe is easy. You can describe it all perfectly and without using more than freshman physics majors know. Introduce a third body, though, and we don’t know anymore. Chaos can happen.

    Emphasis on can. There’s no good way to solve the “general” three-body problem, the one where the star and planets can have any sizes and any starting positions and any starting speeds. We can do well for special cases, though. If you have a sun, a planet, and a satellite — each body negligible compared to the other — we can predict orbits perfectly well. If the bodies have to stay in one plane of motion, instead of moving in three-dimensional space, we can do pretty well. If we know two of the bodies orbit each other tightly and the third is way off in the middle of nowhere we can do pretty well.

    But there’s still so many interesting cases for which we just can’t be sure chaos will not break out. Three interacting bodies just offer so much more chance for things to happen. (To mention something surely coincidental, it does seem to be a lot easier to write good comedy, or drama, with three important characters rather than two. Any pair of characters can gang up on the third, after all. I notice how much more energetic Over The Hedge became when Hammy the Squirrel joined RJ and Verne as the core cast.)

    Dave Whamond’s Reality Check for the 18th is your basic mathematics-illiteracy joke, done well enough.

  • Joseph Nebus 6:00 pm on Tuesday, 21 February, 2017 Permalink | Reply
    Tags: automated proofs, , , ,   

    One Way To Get Your Own Theorem 

    While doing some research to better grouse about Ken Keeler’s Futurama theorem I ran across an amusing site I hadn’t known about. It is Theory Mine, a site that allows you to hire — and name — a genuine, mathematically sound theorem. The spirit of the thing is akin to that scam in which you “name” a star. But this is more legitimate in that, you know, it’s got any legitimacy. For this, you’re buying naming rights from someone who has any rights to sell. By convention the discoverer of a theorem can name it whatever she wishes, and there’s one chance in ten that anyone else will use the name.

    I haven’t used it. I’ve made my own theorems, thanks, and could put them on a coffee mug or t-shirt if I wished to make a particularly boring t-shirt. But I’m delighted by the scheme. They don’t have a team of freelance mathematicians whipping up stuff and hoping it isn’t already known. Not for the kinds of prices they charge. This should inspire the question: well, where do the theorems come from?

    The scheme uses an automated reasoning system. I don’t know the details of how it works, but I can think of a system by which this might work. It goes back to the Crisis of Foundations, the time in the late 19th/early 20th century when logicians got very worried that we were still letting physical intuitions and unstated assumptions stay in our mathematics. One solution: turn everything into symbols, icons with no connotations. The axioms of mathematics become a couple basic symbols. The laws of logical deduction become things we can do with the symbols, converting one line of symbols into a related other line. Every line we get is a theorem. And we know it’s correct. To write out the theorem in this scheme is to write out its proof, and to feel like you’re touching some deep magic. And there’s no human frailties in the system, besides the thrill of reeling off True Names like that.

    You may not be sure what this works like. It may help to compare it to a slightly-fun number coding scheme. I mean the one where you start with a number, like, ‘1’. Then you write down how many times and which digit appears. There’s a single ‘1’ in that string, so you would write down ’11’. And repeat: In ’11’ there’s a sequence of two ‘1’s, so you would write down ’21’. And repeat: there’s a single ‘2’ and a single ‘1’, so you then write down ‘1211’. And again: there’s a single ‘1’, a single ‘2’, and then a double ‘1’, so you next write ‘111221’. And so on until you get bored or die.

    When we do this for mathematics we start with a couple different basic units. And we also start with several things we may do at most symbols. So there’s rarely a single line that follows from the previous. There’s an ever-expanding tree of known truths. This may stave off boredom but I make no promises about death.

    The result of this is pages and pages that look like Ancient High Martian. I don’t feel the thrill of doing this. Some people do, though. And as recreational mathematics goes I suppose it’s at least as good as sudoku. Anyway, this kind of project, rewarding indefatigability and thoroughness, is perfect for automation anyway. Let the computer work out all the things we can prove are true.

    If I’m reading Theory Mine’s description correctly they seem to be doing something roughly like this. If they’re not, well, you go ahead and make your own rival service using my paragraphs as your system. All I ask is one penny for every use of L’Hôpital’s Rule, a theorem named for Guillaume de l’Hôpital and discovered by Johann Bernoulli. (I have heard that Bernoulli was paid for his work, but I do not know that’s true. I have now explained why, if we suppose that to be true, my prior sentence is a very funny joke and you should at minimum chuckle.)

    This should inspire the question: what do we need mathematicians for, then? It’s for the same reason we need writers, when it would be possible to automate the composing of sentences that satisfy the rules of English grammar. I mean if there were rules to English grammar. That we can identify a theorem that’s true does not mean it has even the slightest interest to anyone, ever. There’s much more that could be known than that we could ever care about.

    You can see this in Theory Mine’s example of Quentin’s Theorem. Quentin’s Theorem is about an operation you can do on a set whose elements consist of the non-negative whole numbers with a separate value, which they call color, attached. You can add these colored-numbers together according to some particular rules about how the values and the colors add. The order of this addition normally matters: blue two plus green three isn’t the same as green three plus blue two. Quentin’s Theorem finds cases where, if you add enough colored-numbers together, the order doesn’t matter. I know. I am also staggered by how useful this fact promises to be.

    Yeah, maybe there is some use. I don’t know what it is. If anyone’s going to find the use it’ll be a mathematician. Or a physicist who’s found some bizarre quark properties she wants to codify. Anyway, if what you’re interested in is “what can you do to make a vertical column stable?” then the automatic proof generator isn’t helping you at all. Not without a lot of work put in to guiding it. So we can skip the hard work of finding and proving theorems, if we can do the hard work of figuring out where to look for these theorems instead. Always the way.

    You also may wonder how we know the computer is doing its work right. It’s possible to write software that is logically proven to be correct. That is, the software can’t produce anything but the designed behavior. We don’t usually write software this way. It’s harder to write, because you have to actually design your software’s behavior. And we can get away without doing it. Usually there’s some human overseeing the results who can say what to do if the software seems to be going wrong. Advocates of logically-proven software point out that we’re getting more software, often passing results on to other programs. This can turn a bug in one program into a bug in the whole world faster than a responsible human can say, “I dunno. Did you try turning it off and on again?” I’d like to think we could get more logically-proven software. But I also fear I couldn’t write software that sound and, you know, mathematics blogging isn’t earning me enough to eat on.

    Also, yes, even proven software will malfunction if the hardware the computer’s on malfunctions. That’s rare, but does happen. Fortunately, it’s possible to automate the checking of a proof, and that’s easier to do than creating a proof in the first place. We just have to prove we have the proof-checker working. Certainty would be a nice thing if we ever got it, I suppose.

    • mathtuition88 5:01 am on Wednesday, 22 February, 2017 Permalink | Reply

      Computers are getting more amazing!


      • Joseph Nebus 4:19 pm on Saturday, 25 February, 2017 Permalink | Reply

        They are astounding, which makes it only the more baffling that we can’t get iTunes to reliably download new episodes of a podcast we’re subscribed to and listen to every week.

        Liked by 1 person

    • Henry Game 9:40 am on Wednesday, 22 February, 2017 Permalink | Reply

      One day I’d like you to explain the magic of numbers, vortex maths etc to me. I am interested in numerology, ancient geography, Metatron’s cube and all that, but, for some reason, I have never studied maths.
      Maybe you could inspire me and advise me where to start?
      I thoroughly enjoy your posts, when I come across them, but half the time I am blown away. 😂

      Liked by 1 person

      • Joseph Nebus 4:27 pm on Saturday, 25 February, 2017 Permalink | Reply

        Well, hm. I’m not sure about literal magic of numbers, as in numerology and the like. For what’s wonderful about mathematics … I’m still not perfectly sure. I think I’d give a try of Courant and Robbins’s What Is Mathematics?, originally published in 1940 but still in print and updated, and your library (or university library) will have copies. It’s a little survey of a lot of the fields of mathematics. And it’s mostly episodic, so if one section isn’t doing anything for you it’s fine to skip to the next, or just to pick a section arbitrarily and see what’s going on there.

        And I’m glad you enjoy stuff around here, but if you do get stuck on something please say so! It’s very hard for me to guess what people don’t know, and there’s usually a good post to be made in explaining why something confused someone.

        Liked by 1 person

      • mathtuition88 4:34 pm on Saturday, 25 February, 2017 Permalink | Reply

        I just checked out metatron’s cube, looks really cool.


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