It’s been a quiet week. There’s not a lot of comic strips telling mathematically-themed jokes. Those that were didn’t give me a lot to talk about. And then on Friday nobody came around to even look at my blog. I exaggerate but only barely; I was down to about a quarter the usual low point of page views. I have no explanation for this and I just hope it doesn’t come up again. That’s the sort of thing that’ll break a mere blogger’s heart.

Mike Baldwin’s Cornered for the 12th uses the traditional blackboard — well, whiteboard — full of mathematics to represent intelligence. The symbols aren’t in enough detail to mean anything,

Jeremy Kaye’s Up and Out for the 13th uses a smaller blackboard (whiteboard) full of mathematics to represent intelligence. Here the symbols are more clearly focused, on Boring High School Algebra. It was looking like this might be the blackboard (well, whiteboard)-themed week.

Dan Piraro’s Bizarro for the 14th I admit I don’t quite get. I get that it’s circling around the invention of mathematics and of architecture and all that. And I expect the need to build stuff efficiently helped inspire people to do mathematics. I’m just not sure how the joke quite fits together here. It happens.

Bill Amend’s Fox Trot Classics for the 17th reruns a storyline in which Jason tries to de-nerdify himself. The use of many digits past the decimal make up a lot of what’s left of Jason’s nerdiness. And since it’s easy to overlook let me point this out: 0.0675 percent is only half of the difference between 99.865 percent and 100 percent. It’s not exactly a classic nerd move to use decimal points when a fraction would be at least as good. Digits have a hypnotic power; many people would think 0.25 a more mathematical thing than “one-quarter”. But it is quite nerdly to speak of 0.0675 percent instead of “half of what’s left”.

Some of the past several days’ mathematically-themed comic strips have bits of wordplay in them. That’ll do for the theme. We get some familiar topics along the way.

Rick Detorie’s One Big Happy for the 6th of October is one of the wordplay jokes you can do about probability. (This is the strip that ran in newspapers this year. One Big Happy strips on Gocomics.com are reruns from several years back.)

Tom Thaves’s Frank and Ernest for the 8th of October is a kids-resisting-algebra problem. The kid asks why ‘x’ has to be equal to something, why it can’t just be ‘x’. He’s wiser than his teacher has taught. We use ‘x’ as the name for a number whose exact identity we don’t know right away. Often, especially in introductory algebra, we hope to work out what number it is. That’s the sort of problem that makes us find x, or solve for x. But we don’t always care what x is. Sometimes we just want to say that it’s an example of a number with some interesting properties. We often use it this way when we try drawing the plot of a function. The plot shows all the coordinate sets that make some equation true, and we need x to organize our thoughts about that, but we never really care what x is.

Or we might use x as a ‘dummy variable’, the mathematical equivalent of falsework. We use the variable to get some work done, but never see it once we’re finished, and don’t ever care what it was. If we take the definite integral of a function of x over x, for example, the one thing our answer should not have is an ‘x’ in it. (Well, if we’re integrating some nasty function that can’t be evaluated except in terms of another integral maybe an ‘x’ will appear. But that’s a pathological case.)

Alternatively, x might be a parameter, something which has to be a fixed number for the sake of doing other work, but whose value we don’t really care about. This would be an eccentric choice — usually parameters are from earlier in the alphabet, rarely later than ‘l’ and almost never past ‘t’ — but sometimes that’s the best alternative.

In Jef Mallett’s Frazz for the 8th of October, Caulfield answers his teacher’s demand to “show his work” by presenting a slide rule. It’s a cute joke although I’m not on Caulfield’s side here. If all anyone cared about was whether the calculation was right we’d need no mathematics. We have computers. What is worth teaching is “how do you know what to compute”, with a sideline of “can you do the computations correctly”. It’s important to know what you mean to do. It’s also important to know how to plausibly find an answer if you don’t know exactly what to do. None of that is shown by the answer alone.

Zach Weinersmith’s Saturday Morning Breakfast Cereal for the 9th of October is our Venn Diagram joke for this installment. And it’s not quite a proper Venn diagram, but it’s hard to draw a proper Venn diagram for four propositions. Wikipedia’s entry offers a couple of examples of four-set Venn diagrams. The one made of ellipses is not too bad, although it also evokes “logo for some maybe European cable TV channel” to my eye.

Disney’s Donald Duck for the 10th of October, a rerun from goodness knows when, depicts accurately the most terrifying moment a mathematician endures. I am delighted to see that the equations written out are correct and even consistent from one panel to the next. And yes, real mathematicians will sometimes write down what seem like altogether too-obvious propositions. That’s a good way of making sure you aren’t tripping over the easy stuff on the way to the bigger conclusions. I think it’s a bit implausible that the entire board would be this level of stuff — by the time you have your PhD, at least in mathematics or physics, you don’t need help remembering what the cosine of 120 degrees is — but it’s all valid stuff. Well, I could probably use the help remembering the tangent angle-addition formula, if I ever needed to work out the tangent of the sum of two angles.