## Do good math jokes exist? [closed]

Have a good joke? Share.

I know this is subjective, but the principle "should be of interest to mathematicians" trumps. (I hope.)

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Since this thread continues to interest people, a request: Do people know more jokes that are erudite? That is, jokes that are related to interesting mathematics in some way. (Not necessarily very abstract mathematics.) The Banach-Tarski joke below is a good example, in my opinion. – Greg Kuperberg Nov 22 2009 at 0:11
I just voted this -1, and I'd like to see the question closed. People have had over a month to enjoy it, and its continued presence on the front page seems to encourage people to post very soft questions. This takes Math Overflow in what I think is a bad direction. – Tom Leinster Nov 28 2009 at 12:34
I disagree with Tom. I think some levity is desirable, and MO shouldn't all be serious business. – Richard Dore Dec 10 2009 at 21:50
With respect to the title, "No." – Harry Gindi Dec 10 2009 at 22:23
I've decided to finally put this one out of its misery. All that's happening now is people add new, mostly lame, jokes at the the end, which no one ever reads, and as a result the question keeps bouncing back to the front page. It's time to die. Closed. – Scott Morrison Dec 24 2009 at 2:23

## closed as off topic by S. Carnahan♦, Scott Morrison♦Dec 24 2009 at 2:21

I excuse my english if you spot some flaws...., since this is my first post here I thought it would be nice to share some neat jokes.

1) A mathematician, a physicist and an engineer were out in the countryside when they met a farmer trying to build a fence. They introduced themselves and the farmer asked them if they could help him shape the fence so he would get as much space as possible within it. The engineer stepped forward and said, that it would be best for the farmer to make the fence square, that would be easiest. The physicist then said that it would be better to make it as a circle, because then he would get as much space as possible. The mathematician laughed and said that you can get a lot more space then that! He took some pieces of fence and rolled it around himself, then he defined himself outside the fence!

2) Infinitely many mathematicians walked into a bar, the first one asked for one beer, the next one asked for half a beer, the third one asked for a quarter of a beer and the fourth one asked for one eight of a beer, then the bartender said :"screw this" and filled two glasses of beer!

3) An engineer was working on a problem when suddenly his trash bin caught fire. He immediately grabbed the fire extinguisher and put out the fire. In the next room a physicist was also working on a problem when his trash caught fire, he thought, fire extinguisher block oxygen from the fire, ergo fire is put out. So he grabs the fire extinguisher and puts out the fire. In the third room there was a mathematician working on a problem, his trash bin also caught fire so he looked at and thought, problem has a solution, and continued working!

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jose's post reminds me of one I heard Michael Hutchings tell during an undergraduate calculus lecture:

$e^x$ was walking down the street one day and met a polynomial running in the opposite direction.

"Wait, why are you running?" asked $e^x$. The polynomial said:

"There's a differential operator over there! It could differentiate me and turn me into zero!" And the polynomial continued running in fright.

"Ha ha," $e^x$ said to himself. "I'm $e^x$! Let them differentiate me as many times as they want, it makes no difference to me!" So $e^x$ walked on and reached the differential operator. He confidently introduced himself: "Hi, I'm $e^x$!" The reply:

"Hi, I'm $\partial/\partial y$!"

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Can't stop laughing – DamienC Jun 9 2011 at 20:50
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In a math party, all were having a good time. y was the dj, everybody was Riemmanly drunk. Then, when the x saw e^x on a corner crying, he asked: - Hey e^x, why don't you integrate ? - Because I keep always the same!!!

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Posterior Analysis: when a statistician looks at the rear end of a member of the appropriate sex.

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If I remember correctly someone told me that this really happened:

A famous mathematician gave a talk (maybe about mathematical physics), after which an as famous physicist sitting in the first row got up, and loudly declared: "That's all nice, but without mathematics, research in physics would be maybe a week behind the state it is now!"

The famous mathematician responded: "Yes, the week god needed to create the world."

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After introducing general topological spaces, the professor began to introduce the notion of convergence without a metric. He turned around and said,

"I have no balls."

A hit for months.

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Mathematician1: So why did you become a mathematician?

Mathematician2: I don't like working with numbers.

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a pure and applied mathematician were sitting in a bar, when they spotted a hot chick 2 meters away. However, this was a weird place where they could take one 1 meter step and each consecutive would have to be half of the length of the previous one.

The pure mathematician was sad because he knew he could never get to the girl. The applied one was happy because he knew that for all practical purposes he can get close enough.

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The pure mathematician knew he could make the time gap between each step also half of the previous, and get their in a finite amount of time. – Steven Gubkin May 31 2011 at 12:51

Theorem: There are infinitely many composite numbers.

Proof: Suppose there are only finitely many, and multiply them together.

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What if you do this in the ring of integers mod 6? – Ilya Grigoriev Dec 14 2009 at 22:07
It's crucial in the proof that you multiply the numbers together and do not add one! :) – Somnath Basu Feb 28 2010 at 7:16
What if there is only one composite number? – Douglas S. Stones Mar 6 2010 at 11:45
@ Douglas: There is also a long tradition, beginning with Euclid, of giving Euclid's proof without checking the set of primes is non empty. – roy smith Jan 17 2011 at 17:00
Roy, it's no problem: in that case, per Jérôme's observation, the trick “multiply them all and add 1” gives 2. – L Spice Apr 27 2011 at 18:33

(From the unpublished manuscript "Mathematics in a nutshell":)

A coconut is just a nut

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On a related note, a comathematician is a device for turning cotheorems into ffee. – Michael Lugo Dec 15 2009 at 3:07
you're talking of finite dimensional nuts, ofcourse. – Pietro Majer Jun 14 2011 at 10:08
and cocoa is just 'a' (stolen from a comment on another thread) – David Corwin Dec 28 at 6:21

A British mathematician was giving a talk in Grothendieck's seminar in Paris. He started "Let X be a variety...". This caused some talking among the students sitting in the back, who were asking each other "What's a variety?". J.-P. Serre, sitting in the front row, turns around a bit annoyed and says "Integral scheme of finite type over a field".

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I don't get it... – Kevin Lin Dec 10 2009 at 22:35
It's a dig at an attitude of dealing with abstract concepts without looking at concrete examples first, obviously exaggerated for effect. You need to know some algebraic geometry to understand the punch line. – Felipe Voloch Dec 11 2009 at 1:21
That's pretty funny. – Keenan Kidwell Apr 17 2010 at 23:23
It is a well-established tradition in France to keep the (scheme-theoretic, what else ?) definition of "algebraic variety" in limbo, just to keep the students from getting bogged down into concreteness :-) – Simon Pepin Lehalleur Aug 10 2010 at 21:52
The joke seems to presuppose the distinction between scheme and prescheme. – Lennart Meier Mar 5 2012 at 10:10

Don't remember where I saw this, but as a woman in mathematics, it tickles me no end:

A poet, a priest, and a mathematician are discussing whether it's better to have a wife or a mistress.

The poet argues that it's better to have a mistress because love should be free and spontaneous.

The priest argues that it's better to have a wife because love should be sanctified by God.

The mathematician says, "I think it's better to have both. That way, when each of them thinks you're with the other, you can do some mathematics."

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and what about the lawyer? :) – Sándor Kovács Mar 29 2011 at 5:34
Actually, that reminds me of a joke my mother tells: Q. What's the difference between deer nuts and beer nuts? A. Beer nuts are a dollar fifty, but deer nuts are under a dollar! Maybe it's hereditary. – Elizabeth Henning Apr 3 2011 at 1:55
I don't get it. Does she intentionally say "under a dollar" instead of "under a buck", or accidentally? Or does she not get it? – Keenan Pepper Aug 25 2011 at 23:12

The answer to the question posed in the title "Do Good Math Jokes Exist" is yes and is easily found on google.

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Q: What did the threefold blown up at two points say while waiting in a long line for a restroom?

A: I have to pee too.

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Here is a joke I invented (based on a famous one) and had mixed reaction.

A young mathematician comes to present to a famous mathematician his conjecture and ideas. "You are absolutely wrong," the famous mathematician dismissed the young one. Next enters another young mathematician and presents precisely the opposite conjecture. "You are absolutely wrong" replies the famous mathematician. The famous mathematician's wife interferes. "How could you tell both of them that they are wrong," she sais. "They have made completely opposite claims, one of them must be right!" "You are also wrong," replied the famous mathematician.

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I also find the book Mathematics Made Difficult by Linderholm to be hilarious. I'm not going to search for favorites, but I find the first 2 exercises amusing:

"1. Show that a finite subset of an arbitrary set E in a ring suffices to generate the ideal generated by E if, and only if, the ring is Noetherian.

*2. Show that 17 x 17 = 289. Generalize this result."

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Jonas, what is the answer to the second one? – To be cont'd Jun 12 2010 at 19:45
I should have mentioned that the asterisk on the second problem is to indicate that it is especially difficult. I'm afraid I have not yet solved it. – Jonas Meyer Jun 15 2010 at 3:59

What did the forgetful functor do for his stoner friend?

He left adjoint as a free object.

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I have a few that I've heard and liked.

(1) The Mobius strippers always show their backside.

(2) Apparently, a quote of Paul Erdos, but it's funny nonetheless : Another roof, another proof.

(3) An experimental physicist meets a mathematician in a bar and they start talking. The physicict asks, "What kind of math do you do?" to which the mathematician replies, "Knot theory." The physicist says, "Me neither!"

(4) The primary reason Bourbaki stopped writing books was the realization that Lang was one single person.

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My college roommate and I inadvertently acted out a variation of (3) when I was in a knot theory seminar. It was a rare Abbott-and-Costello-esque moment. – Darsh Ranjan Nov 21 2009 at 9:19
+1 for (4) ... heh :) – Andrew Critch Dec 1 2009 at 10:45

I once ad-libbed this one. (Alas, it is a late entrant.)

Q: Why is it important to study Verma modules of Lie algebras?

A: The most widely used modules of Lie algebras and Lie groups are finite-dimensional irreducible representations, the Weyl modules. Of course, you should learn them first when you study representation theory. But they are only the tip of the iceberg.

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Care to explain the joke to non-specialists? – Boris Bukh Nov 13 2009 at 9:39
If you draw a highest-weight Verma module containing a finite-dimensional representation, e.g. for su(3), it is an infinite iceberg with a finite tip. I suppose that the joke is obscure, even for more most mathematicians. – Greg Kuperberg Nov 13 2009 at 15:04

A friend made this up recently (I prefer the first half on its own):

"No meal is complete without soup. But you have to order it first."

Also I like this meta-joke, also by a friend (who didn't understand the original):

"What's purple and commutes? An abelian eggplant."

EDIT: one more, by Elizabeth: "Does this Hausdorff measure make me look fat?"

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Dear All,

I just stumbled onto this site.

Among other things that I do (chemistry, music), I am a humor theorist who specializes in using mathematical methods to study humor (mostly, I study either the logic of humor or do neuromathematical modeling of how we think the brain responds to humor in places like the pre-frontal cortex and the brainstem).

In any case, I am a reviewer for Humor, which is THE peer-reviewed journal for humor studies and I have written a review of exactly what you are looking for: a book of mathematical humor written by a mathematician. The book is called Comic Sections and was written by the Irish mathematician, Desmond McHale. Unfortunately, Humor is a subscription journal, so the review is unavailable, as is, apparently, the book. It is out of print. If you wish to contact him, his e-mail may be found through the math department at the University of Cork, Ireland.

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Here is the one I heard recently.

Professor: What is a root of $f(z)$ of multiplicity $k$?

Student: It is a number $a$ such that if you plug it into $f$, you get $0$; if you plug it in again, you again get $0$, and so $k$ times. But if you plug it into $f$ for the $k+1$-st time, you do not get $0$.

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Actually, I kind of like this in a serious way :) – David Corwin Dec 28 at 5:37

A millionaire is trying to scientifically develop the best racing horse. He asked a biologist, veterinary, trainer, and a mathematician. The biologist gives him an advice about which type of horse to cross with which other type, the veterinary advices on how to feed the horse, and how to keep him healthy, the trainer explains how to physically train the horse. The mathematician does not reply. After a few weeks the millionaire meets the mathematician and it looks that the mathematician did not sleep much in recent days. Do you have a solution for me, ask the millionaire? It is a difficult problem, answers the mathematician, but I think I have a satisfactory solution to the case of spherical horses.

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The version I know of this joke has a physicist proposing a solution for spherical horses. The mathematician thinks long and hard, and announces that she has solved the problem: she can prove that, for every horse race, there exists a unique winner. – Nate Eldredge Nov 30 2010 at 16:49

Q: What is non-orientable and lives in the ocean?
A: Möbius Dick...

A mathematician organizes a raffle in which the prize is an infinite amount of money paid over an infinite amount of time. Of course, with the promise of such a prize, his tickets sell like hot cake.

When the winning ticket is drawn, and the jubilant winner comes to claim his prize, the mathematician explains the mode of payment: "1 dollar now, 1/2 dollar next week, 1/3 dollar the week after that..."

"The number you have dialed is imaginary. Please, rotate your phone by 90 degrees and try again..."

From a former prof. - http://www.math.ualberta.ca/~runde/jokes.html

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Too much time spent on the internets makses the "Möbius Dick" joke close to incomprehensible... – darij grinberg Jan 11 2011 at 22:00

Less of a joke than an observation, but...

I've always found it appropriate that online identity thieves are in the business of stealing ones and zeroes.

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@Qiaochu Yuan: One and zero are identities. :-) – shreevatsa Jul 8 2010 at 4:34

Q: What's purple and commutes? A: A dead baby in a suitcase.

Q: What's purple and commutes and has a certain number of followers? A: A dead baby Jesus in a suitcase.

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Excellent! Only a mathematician would get this! – Steven Gubkin Mar 5 2010 at 18:08
a mix of math jokes with dead babies, and they said it could'nt be done... – Sean Tilson Mar 6 2010 at 1:19

Q: What's purple and commutes? A: An abelian grape!

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I first heard this on an episode of the Big Bang Theory, I don't know the origin.

The physicist asks the mathematician: "Why did the chicken cross the road?"

The mathematician ponders a while and then replies: "I have a solution, but it only works for a spherical chicken in a vacuum."

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Here's a legend we have at our institute:

Prof: "Give an example of a vector space."

Student: "V"

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It'd be funny if it weren't true. – lhf Dec 26 2009 at 0:13
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