## Reading the Comics, October 10, 2015: Wordplay Edition

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, 2015. Ruthie works out the odds.

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.)

Niklas Eriksson’s Carpe Diem for the 6th of October is a badly-timed Pi Day strip.

Niklas Eriksson’s Carpe Diem for the 6th of October, 2015.

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.

Jim Benton’s Jim Benton Cartoons for the 8th of October is some more mathematics wordplay. I’m amused by its logic.

Samson’s Dark Side of the Horse for the 9th of October is the first anthropomorphized-numerals joke we’ve had in a while.

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, 2015. A tough moment for any academician.

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.