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  • Joseph Nebus 6:00 pm on Sunday, 23 April, 2017 Permalink | Reply
    Tags: , , , Edison Lee, , Lug Nuts, , ,   

    Reading the Comics, April 18, 2017: Give Me Some Word Problems Edition 


    I have my reasons for this installment’s title. They involve my deductions from a comic strip. Give me a few paragraphs.

    Mark Anderson’s Andertoons for the 16th asks for attention from whatever optician-written blog reads the comics for the eye jokes. And meets both the Venn Diagram and the Mark Anderson’s Andertoons content requirements for this week. Good job! Starts the week off strong.

    Lincoln Pierce’s Big Nate: First Class for the 16th, rerunning the strip from 1993, is about impossibly low-probability events. We can read the comic as a joke about extrapolating a sequence from a couple examples. Properly speaking we can’t; any couple of terms can be extended in absolutely any way. But we often suppose a sequence follows some simple pattern, as many real-world things do. I’m going to pretend we can read Jenny’s estimates of the chance she’ll go out with him as at all meaningful. If Jenny’s estimate of the chance she’d go out with Nate rose from one in a trillion to one in a billion over the course of a week, this could be a good thing. If she’s a thousand times more likely each week to date him — if her interest is rising geometrically — this suggests good things for Nate’s ego in three weeks. If she’s only getting 999 trillionths more likely each week — if her interest is rising arithmetically — then Nate has a touch longer to wait before a date becomes likely.

    (I forget whether she has agreed to a date in the 24 years since this strip first appeared. He has had some dates with kids in his class, anyway, and some from the next grade too.)

    J C Duffy’s Lug Nuts for the 16th is a Pi Day joke that ran late.

    Jef Mallett’s Frazz for the 17th starts a little thread about obsolete references in story problems. It’s continued on the 18th. I’m sympathetic in principle to both sides of the story problem debate.

    Is the point of the first problem, Farmer Joe’s apples, to see whether a student can do a not-quite-long division? Or is it to see whether the student can extract a price-per-quantity for something, and apply that to find the quantity to fit a given price? If it’s the latter then the numbers don’t make a difference. One would want to avoid marking down a student who knows what to do, and could divide 15 cents by three, but would freeze up if a more plausible price of, say, $2.25 per pound had to be divided by three.

    But then the second problem, Mr Schad driving from Belmont to Cadillac, got me wondering. It is about 84 miles between the two Michigan cities (and there is a Reed City along the way). The time it takes to get from one city to another is a fair enough problem. But these numbers don’t make sense. At 55 miles per hour the trip takes an awful 1.5273 hours. Who asks elementary school kids to divide 84 by 55? On purpose? But at the state highway speed limit (for cars) of 70 miles per hour, the travel time is 1.2 hours. 84 divided by 70 is a quite reasonable thing to ask elementary school kids to do.

    And then I thought of this: you could say Belmont and Cadillac are about 88 miles apart. Google Maps puts the distance as 86.8 miles, along US 131; but there’s surely some point in the one town that’s exactly 88 miles from some point in the other, just as there’s surely some point exactly 84 miles from some point in the other town. 88 divided by 55 would be another reasonable problem for an elementary school student; 1.6 hours is a reasonable answer. The (let’s call it) 1980s version of the question ought to see the car travel 88 miles at 55 miles per hour. The contemporary version ought to see the car travel 84 miles at 70 miles per hour. No reasonable version would make it 84 miles at 55 miles per hour.

    So did Mallett take a story problem that could actually have been on an era-appropriate test and ancient it up?

    Before anyone reports me to Comic Strip Master Command let me clarify what I’m wondering about. I don’t care if the details of the joke don’t make perfect sense. They’re jokes, not instruction. All the story problem needs to set up the joke is the obsolete speed limit; everything else is fluff. And I enjoyed working out variation of the problem that did make sense, so I’m happy Mallett gave me that to ponder.

    Here’s what I do wonder about. I’m curious if story problems are getting an unfair reputation. I’m not an elementary school teacher, or parent of a kid in school. I would like to know what the story problems look like. Do you, the reader, have recent experience with the stuff farmers, drivers, and people weighing things are doing in these little stories? Are they measuring things that people would plausibly care about today, and using values that make sense for the present day? I’d like to know what the state of story problems is.

    Lee: 'I'm developing a new theory about avocado intelligence.' Joules: 'You can't be serious.' Lee: 'Avocado, what is the square root of 8,649?' Avocado: 'That's easy. It's 92?' Lee: 'Wrong. It's 93.' Joules: 'See? It's just a dumb piece of fruit.' Lee: 'I honestly thought I was on to something.'

    John Hambrock’s The Brilliant Mind of Edison Lee for the 18th of April, 2017. Before you ask what exactly the old theory of avocado intelligence was remember that Edison Lee’s lab partner there is a talking rat. Just saying.

    John Hambrock’s The Brilliant Mind of Edison Lee for the 18th uses mental arithmetic as the gauge of intelligence. Pretty harsly, too. I wouldn’t have known the square root of 8649 off the top of my head either, although it’s easy to tell that 92 can’t be right: the last digit of 92 squared has to be 4. It’s also easy to tell that 92 has to be about right, though, as 90 times 90 will be about 8100. Given this information, if you knew that 8,649 was a perfect square, you’d be hard-pressed to think of a better guess for its value than 93. But since most whole numbers are not perfect squares, “a little over 90” is the best I’d expect to do.

     
  • Joseph Nebus 6:00 pm on Friday, 21 April, 2017 Permalink | Reply
    Tags: , , Mobius strips,   

    In Which I Offer Excuses Instead Of Mathematics 


    I’d been hoping to get back into longer-form essays. And then the calculations I meant to do on one problem turned out more complicated than I’d wanted. And they’re hard to square with the approach I used in some earlier work. Not that the results I was looking at were wrong, mind, just that an approach I’d used as “convenient for this sort of problem” turned inconvenient here.

    So while I have the whole piece back in the shop for re-thinking, which is harder than even thinking, let me give you some other stuff to read. Or look at. One is from regular Singaporean correspondent MathTuition88. If you know anything about topology it’s because you’ve heard about Möbius strips. Surfaces with a single side are neat, and form the base of 95 percent of all science fiction stories in which the mathematics is the fantastic element. Klein bottles are often mentioned as a four-dimensional analogue to the Möbius strip, a solid object with no distinguishable interior or exterior. And a Klein bottle can be divided into two Möbius strips. MathTuition88 showcases a picture about how to turn two strips into a bottle. Or at least the best approximation of a bottle we can do; the actual Klein bottle is a four-dimensional structure and we can just make a three-dimensional imitation of the thing.

    For something a bit more vector-analytic Joe Heafner’s Tensor Time has an essay about vectors. It’s about Heafner’s dislike for the way some vector problems are presented. Some common and easy ways to solve vector equations lead to spurious solutions that have to be weeded out by ad hoc reasoning; can’t we do better? Heafner argues that we can and should. The suggested alternative looks a little stuffy, but as often happens, spending more time on the setup means one spends less time confused later on. Worth pondering.

    And this is a late addition, but I couldn’t resist.

    Now I have a new favorite first chapter for a calculus text.

     
  • Joseph Nebus 6:00 pm on Tuesday, 18 April, 2017 Permalink | Reply
    Tags: , Duncan Steel, Easter, ,   

    What Is The Most Probable Date For Easter? What Is The Least? 


    If I’d started pondering the question a week earlier I’d have a nice timely post. Too bad. Shouldn’t wait nearly a year to use this one, though.

    My love and I got talking about early and late Easters. We know that we’re all but certainly not going to be alive to see the earliest possible Easter, at least not unless the rule for setting the date of Easter changes. Easter can be as early as the 22nd of March or as late as the 25th of April. Nobody presently alive has seen a 22nd of March Easter; the last one was in 1818. Nobody presently alive will; the next will be 2285. The last time Easter was its latest date was 1943; the next time will be 2038. I know people who’ve seen the one in 1943 and hope to make it at least through 2038.

    But that invites the question: what dates are most likely to be Easter? What ones are least? In a sense the question is nonsense. The rules establishing Easter and the Gregorian calendar are known. To speak of the “chance” of a particular day being Easter is like asking the probability that Grover Cleveland was president of the United States in 1894. Technically there’s a probability distribution there. But it’s different in some way from asking the chance of rolling at least a nine on a pair of dice.

    But as with the question about what day is most likely to be Thanksgiving we can make the question sensible. We have to take the question to mean “given a month and day, and no information about what year it is, what is the chance that this as Easter?” (I’m still not quite happy with that formulation. I’d be open to a more careful phrasing, if someone’s got one.)

    When we’ve got that, though, we can tackle the problem. We could do as I did for working out what days are most likely to be Thanksgiving. Run through all the possible configurations of the calendar, tally how often each of the days in the range is Easter, and see what comes up most often. There’s a hassle here. Working out the date of Easter follows a rule, yes. The rule is that it’s the first Sunday after the first full moon after the spring equinox. There are wrinkles, mostly because the Moon is complicated. A notional Moon that’s a little more predictable gets used instead. There are algorithms you can use to work out when Easter is. They all look like some kind of trick being used to put something over on you. No matter. They seem to work, as far as we know. I found some Matlab code that uses the Easter-computing routine that Karl Friedrich Gauss developed and that’ll do.

    Problem. The Moon and the Earth follow cycles around the sun, yes. Wait long enough and the positions of the Earth and Moon and Sun. This takes 532 years and is known as the Paschal Cycle. In the Julian calendar Easter this year is the same date it was in the year 1485, and the same it will be in 2549. It’s no particular problem to set a computer program to run a calculation, even a tedious one, 532 times. But it’s not meaningful like that either.

    The problem is the Julian calendar repeats itself every 28 years, which fits nicely with the Paschal Cycle. The Gregorian calendar, with different rules about how to handle century years like 1900 and 2100, repeats itself only every 400 years. So it takes much longer to complete the cycle and get Earth, Moon, and calendar date back to the same position. To fully account for all the related cycles would take 5,700,000 years, estimates Duncan Steel in Marking Time: The Epic Quest To Invent The Perfect Calendar.

    Write code to calculate Easter on a range of years and you can do that, of course. It’s no harder to calculate the dates of Easter for six million years than it is for six hundred years. It just takes longer to finish. The problem is that it is meaningless to do so. Over the course of a mere(!) 26,000 years the precession of the Earth’s axes will change the times of the seasons completely. If we still use the Gregorian calendar there will be a time that late September is the start of the Northern Hemisphere’s spring, and another time that early February is the heart of the Canadian summer. Within five thousand years we will have to change the calendar, change the rule for computing Easter, or change the idea of it as happening in Europe’s early spring. To calculate a date for Easter of the year 5,002,017 is to waste energy.

    We probably don’t need it anyway, though. The differences between any blocks of 532 years are, I’m going to guess, minor things. I would be surprised if the frequency of any date’s appearance changed more than a quarter of a percent. That might scramble the rankings of dates if we have several nearly-as-common dates, but it won’t be much.

    So let me do that. Here’s a table of how often each particular calendar date appears as Easter from the years 2000 to 5000, inclusive. And I don’t believe that by the year we would call 5000 we’ll still have the same calendar and Easter and expectations of Easter all together, so I’m comfortable overlooking that. Indeed, I expect we’ll have some different calendar or Easter or expectation of Easter by the year 4985 at the latest.

    For this enormous date range, though, here’s the frequency of Easters on each possible date:

    Date Number Of Occurrences, 2000 – 5000 Probability Of Occurence
    22 March 12 0.400%
    23 March 17 0.566%
    24 March 41 1.366%
    25 March 74 2.466%
    26 March 75 2.499%
    27 March 68 2.266%
    28 March 90 2.999%
    29 March 110 3.665%
    30 March 114 3.799%
    31 March 99 3.299%
    1 April 87 2.899%
    2 April 83 2.766%
    3 April 106 3.532%
    4 April 112 3.732%
    5 April 110 3.665%
    6 April 92 3.066%
    7 April 86 2.866%
    8 April 98 3.266%
    9 April 112 3.732%
    10 April 114 3.799%
    11 April 96 3.199%
    12 April 88 2.932%
    13 April 90 2.999%
    14 April 108 3.599%
    15 April 117 3.899%
    16 April 104 3.466%
    17 April 90 2.999%
    18 April 93 3.099%
    19 April 114 3.799%
    20 April 116 3.865%
    21 April 93 3.099%
    22 April 60 1.999%
    23 April 46 1.533%
    24 April 57 1.899%
    25 April 29 0.966%
    Bar chart representing the data in the table above.

    Dates of Easter from 2000 through 5000. Computed using Gauss’s algorithm.

    If I haven’t missed anything, this indicates that the 15th of April is the most likely date for Easter, with the 20th close behind and the 10th and 14th hardly rare. The least probable date is the 22nd of March, with the 23rd of March and the 25th of April almost as unlikely.

    And since the date range does affect the results, here’s a smaller sampling, one closer fit to the dates of anyone alive to read this as I publish. For the years 1925 through 2100 the appearance of each Easter date are:

    Date Number Of Occurrences, 1925 – 2100 Probability Of Occurence
    22 March 0 0.000%
    23 March 1 0.568%
    24 March 1 0.568%
    25 March 3 1.705%
    26 March 6 3.409%
    27 March 3 1.705%
    28 March 5 2.841%
    29 March 6 3.409%
    30 March 7 3.977%
    31 March 7 3.977%
    1 April 6 3.409%
    2 April 4 2.273%
    3 April 6 3.409%
    4 April 6 3.409%
    5 April 7 3.977%
    6 April 7 3.977%
    7 April 4 2.273%
    8 April 4 2.273%
    9 April 6 3.409%
    10 April 7 3.977%
    11 April 7 3.977%
    12 April 7 3.977%
    13 April 4 2.273%
    14 April 6 3.409%
    15 April 7 3.977%
    16 April 6 3.409%
    17 April 7 3.977%
    18 April 6 3.409%
    19 April 6 3.409%
    20 April 6 3.409%
    21 April 7 3.977%
    22 April 5 2.841%
    23 April 2 1.136%
    24 April 2 1.136%
    25 April 2 1.136%
    Bar chart representing the data in the table above.

    Dates of Easter from 1925 through 2100. Computed using Gauss’s algorithm.

    If we take this as the “working lifespan” of our common experience then the 22nd of March is the least likely Easter we’ll see, as we never do. The 23rd and 24th are the next least likely Easter. There’s a ten-way tie for the most common date of Easter, if I haven’t missed one or more. But the 30th and 31st of March, and the 5th, 6th, 10th, 11th, 12th, 15th, 17th, and 21st of April each turn up seven times in this range.

    The Julian calendar Easter dates are different and perhaps I’ll look at that sometime.

     
  • Joseph Nebus 6:00 pm on Sunday, 16 April, 2017 Permalink | Reply
    Tags: Amanda the Great, , , , , , , Gentle Creatures, , , Skin Horse, , Strange Brew,   

    Reading the Comics, April 15, 2017: Extended Week Edition 


    It turns out last Saturday only had the one comic strip that was even remotely on point for me. And it wasn’t very on point either, but since it’s one of the Creators.com strips I’ve got the strip to show. That’s enough for me.

    Henry Scarpelli and Craig Boldman’s Archie for the 8th is just about how algebra hurts. Some days I agree.

    'Ugh! Achey head! All blocked up! Throbbing! Completely stuffed!' 'Sounds like sinuses!' 'No. Too much algebra!'

    Henry Scarpelli and Craig Boldman’s Archie for the 8th of April, 2017. Do you suppose Archie knew that Dilton was listening there, or was he just emoting his fatigue to himself?

    Ruben Bolling’s Super-Fun-Pak Comix for the 8th is an installation of They Came From The Third Dimension. “Dimension” is one of those oft-used words that’s come loose of any technical definition. We use it in mathematics all the time, at least once we get into Introduction to Linear Algebra. That’s the course that talks about how blocks of space can be stretched and squashed and twisted into each other. You’d expect this to be a warmup act to geometry, and I guess it’s relevant. But where it really pays off is in studying differential equations and how systems of stuff changes over time. When you get introduced to dimensions in linear algebra they describe degrees of freedom, or how much information you need about a problem to pin down exactly one solution.

    It does give mathematicians cause to talk about “dimensions of space”, though, and these are intuitively at least like the two- and three-dimensional spaces that, you know, stuff moves in. That there could be more dimensions of space, ordinarily inaccessible, is an old enough idea we don’t really notice it. Perhaps it’s hidden somewhere too.

    Amanda El-Dweek’s Amanda the Great of the 9th started a story with the adult Becky needing to take a mathematics qualification exam. It seems to be prerequisite to enrolling in some new classes. It’s a typical set of mathematics anxiety jokes in the service of a story comic. One might tsk Becky for going through university without ever having a proper mathematics class, but then, I got through university without ever taking a philosophy class that really challenged me. Not that I didn’t take the classes seriously, but that I took stuff like Intro to Logic that I was already conversant in. We all cut corners. It’s a shame not to use chances like that, but there’s always so much to do.

    Mark Anderson’s Andertoons for the 10th relieves the worry that Mark Anderson’s Andertoons might not have got in an appearance this week. It’s your common kid at the chalkboard sort of problem, this one a kid with no idea where to put the decimal. As always happens I’m sympathetic. The rules about where to move decimals in this kind of multiplication come out really weird if the last digit, or worse, digits in the product are zeroes.

    Mel Henze’s Gentle Creatures is in reruns. The strip from the 10th is part of a story I’m so sure I’ve featured here before that I’m not even going to look up when it aired. But it uses your standard story problem to stand in for science-fiction gadget mathematics calculation.

    Dave Blazek’s Loose Parts for the 12th is the natural extension of sleep numbers. Yes, I’m relieved to see Dave Blazek’s Loose Parts around here again too. Feels weird when it’s not.

    Bill Watterson’s Calvin and Hobbes rerun for the 13th is a resisting-the-story-problem joke. But Calvin resists so very well.

    John Deering’s Strange Brew for the 13th is a “math club” joke featuring horses. Oh, it’s a big silly one, but who doesn’t like those too?

    Dan Thompson’s Brevity for the 14th is one of the small set of punning jokes you can make using mathematician names. Good for the wall of a mathematics teacher’s classroom.

    Shaenon K Garrity and Jefferey C Wells’s Skin Horse for the 14th is set inside a virtual reality game. (This is why there’s talk about duplicating objects.) Within the game, the characters are playing that game where you start with a set number (in this case 20) tokens and take turn removing a couple of them. The “rigged” part of it is that the house can, by perfect play, force a win every time. It’s a bit of game theory that creeps into recreational mathematics books and that I imagine is imprinted in the minds of people who grow up to design games.

     
  • Joseph Nebus 6:00 pm on Friday, 14 April, 2017 Permalink | Reply
    Tags: , , , ,   

    What Is The Logarithm of a Negative Number? 


    Learning of imaginary numbers, things created to be the square roots of negative numbers, inspired me. It probably inspires anyone who’s the sort of person who’d become a mathematician. The trick was great. I wondered could I do it? Could I find some other useful expansion of the number system?

    The square root of a complex-valued number sounded like the obvious way to go, until a little later that week when I learned that’s just some other complex-valued numbers. The next thing I hit on: how about the logarithm of a negative number? Couldn’t that be a useful expansion of numbers?

    No. It turns out you can make a sensible logarithm of negative, and complex-valued, numbers using complex-valued numbers. Same with trigonometric and inverse trig functions, tangents and arccosines and all that. There isn’t anything we can do with the normal mathematical operations that needs something bigger than the complex-valued numbers to play with. It’s possible to expand on the complex-valued numbers. We can make quaternions and some more elaborate constructs there. They don’t solve any particular shortcoming in complex-valued numbers, but they’ve got their uses. I never got anywhere near reinventing them. I don’t regret the time spent on that. There’s something useful in trying to invent something even if it fails.

    One problem with mathematics — with all intellectual fields, really — is that it’s easy, when teaching, to give the impression that this stuff is the Word of God, built into the nature of the universe and inarguable. It’s so not. The stuff we find interesting and how we describe those things are the results of human thought, attempts to say what is interesting about a thing and what is useful. And what best approximates our ideas of what we would like to know. So I was happy to see this come across my Twitter feed:

    The links to a 12-page paper by Deepak Bal, Leibniz, Bernoulli, and the Logarithms of Negative Numbers. It’s a review of how the idea of a logarithm of a negative number got developed over the course of the 18th century. And what great minds, like Gottfried Leibniz and John (I) Bernoulli argued about as they find problems with the implications of what they were doing. (There were a lot of Bernoullis doing great mathematics, and even multiple John Bernoullis. The (I) is among the ways we keep them sorted out.) It’s worth a read, I think, even if you’re not all that versed in how to calculate logarithms. (but if you’d like to be better-versed, here’s the tail end of some thoughts about that.) The process of how a good idea like this comes to be is worth knowing.

    Also: it turns out there’s not “the” logarithm of a complex-valued number. There’s infinitely many logarithms. But they’re a family, all strikingly similar, so we can pick one that’s convenient and just use that. Ask if you’re really interested.

     
  • Joseph Nebus 6:00 pm on Wednesday, 12 April, 2017 Permalink | Reply
    Tags: , ,   

    Did This German Retiree Solve A Decades-Old Conjecture? 


    And then this came across my desktop (my iPad’s too old to work with the Twitter client anymore):

    The underlying news is that one Thomas Royen, a Frankfurt (Germany)-area retiree, seems to have proven the Gaussian Correlation Inequality. It wasn’t a conjecture that sounded familiar to me, but the sidebar (on the Quanta Magazine article to which I’ve linked there) explains it and reminds me that I had heard about it somewhere or other. It’s about random variables. That is, things that can take on one of a set of different values. If you think of them as the measurements of something that’s basically consistent but never homogenous you’re doing well.

    Suppose you have two random variables, two things that can be measured. There’s a probability the first variable is in a particular range, greater than some minimum and less than some maximum. There’s a probability the second variable is in some other particular range. What’s the probability that both variables are simultaneously in these particular ranges? This is easy to answer for some specific cases. For example if the two variables have nothing to do with each other then everybody who’s taken a probability class knows. The probability of both variables being in their ranges is the probability the first is in its range times the probability the second is in its range. The challenge is telling whether it’s always true, whether the variables are related to each other or not. Or telling when it’s true if it isn’t always.

    The article (and pop reporting on this) is largely about how the proof has gone unnoticed. There’s some interesting social dynamics going on there. Royen published in an obscure-for-the-field journal, one he was an editor for; this makes it look dodgy, at least. And the conjecture’s drawn “proofs” that were just wrong; this discourages people from looking for obscurely-published proofs.

    Some of the articles I’ve seen on this make Royen out to be an amateur. And I suppose there is a bias against amateurs in professional mathematics. There is in every field. It’s true that mathematics doesn’t require professional training the way that, say, putting out oil rig fires does. Anyone capable of thinking through an argument rigorously is capable of doing important original work. But there are a lot of tricks to thinking an argument through that are important, and I’d bet on the person with training.

    In any case, Royen isn’t a newcomer to the field who just heard of an interesting puzzle. He’d been a statistician, first for a pharmaceutical company and then for a technical university. He may not have a position or tie to a mathematics department or a research organization but he’s someone who would know roughly what to do.

    So did he do it? I don’t know; I’m not versed enough in the field to say. It’s interesting to see if he has.

     
  • Joseph Nebus 6:00 pm on Sunday, 9 April, 2017 Permalink | Reply
    Tags: , chess, Family Circus, , , 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 ;-)

      Like

  • 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:

    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…

      Like

      • 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 :-) )
          .

          Like

          • 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?

      Like

      • 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:

  • 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 (*)

    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: , , , Moderately Confused, 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.

      Like

      • 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.

        Like

    • 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.

      Like

      • 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.

        Like

  • Joseph Nebus 6:00 pm on Sunday, 19 March, 2017 Permalink | Reply
    Tags: 2 Cows And A Chicken, , , Arlo and Janis, Lard's World Peace Tips, , 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.

  • 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 %
    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.

     
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