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∫ex = f(un)


The first time I saw this joke was when I arrived at Caltech. Some silly bastard was writing it on everyone's white boards.

I'm actually such a geek that somebody had to explain this joke to me-- I kept wondering how the indefinite integral of ex was humorous.

If you don't get it, try not to think about it too hard. It's really not that sophisticated of a joke.

Appearing under My favorite math joke is another joke which claims the title of shortest math joke:

Let |epsilon| < 0.

While yours has less characters, this one seems to be simpler, more elegant, somehow; I think, therefore, that it is more deserving of the title.

Note 1: When I first wrote this, I didn't even spot the similar one at the top of the node; I would like to point out, though, that without the absolute value, the joke doesn't really work.

Note 2: People have been asking me for an explanation of the joke. Here goes. The basis of it is that fact that |epsilon| > 0 frequently appears in delta-epsilon proofs, and in other math too I would guess. The pun in |epsilon| < 0 is that, though it looks almost like |epsilon| > 0, which is legitimate, an absolute value cannot be less than 0. That is, |x| means the absolute value of x, which means remove the sign from x, make it positive. Thus while |epsilon| < 0 at first glance (and second glance) looks perfectly normal, after a moment, math nerds notice that it is completely impossible and nonsensical, which to me is the irony which makes it funny. There, I've dissected it, you happy now? :-D

A longer version of somok's joke that my highschool's senior class printed on the backs of our t-shirts for homecoming is this:

 Σ ∫ex= f(un) ∴ yo
u→xc
which reads:

As u approaches x to the c power, the indefinite integral of e to the x is equal to the function u sub n, therefore: y sub zero (or y naught)

OR:

As you approach ecstacy, sex is fun, so why not?

There were a lot of geeks in my senior class, yes, and no, we didn't get in trouble for the shirts. The only teacher who worked out what it said was a horny old bastard who thought the shirts were fantastic.

I HAVE BEEN TOLD THAT THIS IS NOT EASILY VIEWABLE ON SOME INTERNET BROWSERS. I WILL FIX IT AS SOON AS I CAN FIGURE OUT HOW.

THANKS TO rootbeer277 FOR THE FORMATTING ASSISTANCE.

Being a fan of mathematical logic and deduction, I found the following math joke to be elegant, punny, and utterly hilarious.

∀∀∃∃

For those who don't speak math, an explanation follows.

'∀' and '∃' are what mathematicians call quantifiers in logic: the former is the universal quantifier, and the latter is the existential quantifier. They're usually followed by the variable they quantify, and then the expression in which they quantify it, and are basically used in logical theorems to denote how certain variables should be treated.

Much like in lambda calculus, and any other field that requires rigorous treatment of unknowns such as variables, variables can exist as either free or bound. A free variable is one to which no actions or values have yet been prescribed to, while a bound variable is bound by a quantifier. When a variable is universally quantified, this means that the statement in which it exist should be treated as if any possible legal value for the bound variable would be true. Likewise, an existential quantification on a variable means that there is at least one possible value for which the statement is true.

For example, the statement "∀x (∃y (x = 2 * y))" is saying that for all numbers x, there exists a number y such that twice y equals x. More meaningfully, it asserts that for every number, you can find half that number, a statement which is true over the real numbers.

The actual meaning of the joke relies on knowing that many statements in number theory end up quantifying two variables to manipulate, one with ∀ and one with ∃. Hence, the assertion that for all ∀ symbols, there exists a ∃ symbol nearby.

[IN12#24]

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