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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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closed as off topic by S. Carnahan, Scott Morrison Dec 24 '09 at 2:21

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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 '09 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 '09 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 '09 at 21:50
With respect to the title, "No." – Harry Gindi Dec 10 '09 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 '09 at 2:23

81 Answers 81

There's a Notices article on this.

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The jokes in that article are terrible, though. – Qiaochu Yuan Oct 18 '09 at 22:04
@Qiaochu: But the article itself is kind of hilarious. – Harrison Brown Oct 18 '09 at 22:09

I've always thought that "What's the value of a contour integral around Western Europe?" "Zero. All the Poles are in Eastern Europe." was pretty good, although not laugh-out-loud funny by any means.

Another one I personally like is "What's an anagram of Banach-Tarski?" "Banach-Tarski Banach-Tarski."

It's not really a "joke," (and whether it's "mathematical" is, I suppose, debatable), but Knuth's article on the complexity of songs is pretty great.

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The Banach-Tarski joke is very good. – Greg Kuperberg Nov 21 '09 at 23:59
The first joke to me sounds like a debased version of the following joke, which was quite topical in about 2004: "Q: What's the value of the contour integral around the British Isles? A: Zero, because all the Poles are removable". This refers to the fact that at the time the joke was coined, Britain was host to a large number of Polish migrant workers who were in the unusual position of being intra-EU migrants not having indefinite leave to remain in Britain. – Ian Morris Nov 23 '09 at 13:32
I would imagine the variant given was around before 2004. – Sean Tilson Mar 6 '10 at 0:31
The Banach-Tarski paradox is all about the free grape. – Gene S. Kopp Nov 9 '10 at 9:42
Here is a joke in the same vein as the Banach-Tarksi one. What does the B stand for in Benoit B. Mandelbrot? Benoit B. Mandelbrot. – Michael Albanese Sep 17 '13 at 5:28

Tom Lehrer was a Mathematician and this comes through in several of his famous skits. Not precisely a "math joke", but still mathy and pretty darn funny.

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Tom Lehrer was a genious. His song "Werner von Braun" is absolutely brilliant. – Grétar Amazeen Oct 18 '09 at 23:58
I hope Tom Lehrer still is a genius - I believe he's still alive :-) and yes, that's absolutely true. His wordplay and clever humor are really masterful. – Alon Amit Oct 19 '09 at 2:11
He was my calculus section man in 1960 and apparently a democrat, since he proposed as an example of proof by vacuous hypothesis the statement: "all progressive republicans wear green eyeshades". – roy smith Sep 1 '11 at 16:09

An excerpt from H. Petard, "A contribution to the mathematical theory of big game hunting," The American Mathematical Monthly, vol. 45, no. 7, pp. 446-447, 1938:

The Hilbert, or axiomatic, method. We place a locked cage at a given point of the desert. We then introduce the following logical system.

  • Axiom I. The class of lions in the Sahara Desert is non-void.
  • Axiom II. If there is a lion in the Sahara Desert, there is a lion in the cage.
  • Rule of Procedure. If p is a theorem, and "p implies q" is a theorem, then q is a theorem.
  • Theorem I. There is a lion in the cage.

The method of inversive geometry. We place a spherical cage in the desert, enter it, and lock it. We perform an inversion with respect to the cage. The lion is then in the interior of the cage, and we are outside.

The method of projective geometry. Without loss of generality, we may regard the Sahara Desert as a plane. Project the plane into a line, and then project the line into an interior point of the cage. The lion is projected into the same point.

The Bolzano-Weierstrass method. Bisect the desert by a line running N-S. The lion is either in the E portion or in the W portion; let us suppose him to be in the W portion. Bisect this portion by a line running E-W. The lion is either in the N portion or in the S portion; let us suppose him to be in the N portion. We continue this process indefinitely, constructing a sufficiently strong fence about the chosen portion at each step. The diameter of the chosen portions approaches zero, so that the lion is ultimately surrounded by a fence of arbitrarily small perimeter.

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It's hard to beat the following for simplicity (or agreement with mathematical practice): go into the cage, lock it, and declare yourself to be on the outside. – Hugh Thomas Oct 19 '09 at 17:11

A mathematician in a job interview was asked, "We need to see what kind of attitude you have toward problem solving. So tell us, is the glass half empty or half full."

His reply, "It's 1-x."

-William Mauritzen

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"Finite Simple Group (of Order Two)" by the Klein Four a cappella group at Northwestern University (lyrics by Matt Salomone):

The path of love is never smooth
But mine's continuous for you
You're the upper bound in the chains of my heart
You're my Axiom of Choice, you know it's true

But lately our relation's not so well-defined
And I just can't function without you
I'll prove my proposition and I'm sure you'll find
We're a finite simple group of order two

I'm losing my identity
I'm getting tensor every day
And without loss of generality
I will assume that you feel the same way

Since every time I see you, you just quotient out
The faithful image that I map into
But when we're one-to-one you'll see what I'm about
'Cause we're a finite simple group of order two

Our equivalence was stable,
A principal love bundle sitting deep inside
But then you drove a wedge between our two-forms
Now everything is so complexified

When we first met, we simply connected
My heart was open but too dense
Our system was already directed
To have a finite limit, in some sense

I'm living in the kernel of a rank-one map
From my domain, its image looks so blue,
'Cause all I see are zeroes, it's a cruel trap
But we're a finite simple group of order two

I'm not the smoothest operator in my class,
But we're a mirror pair, me and you,
So let's apply forgetful functors to the past
And be a finite simple group, a finite simple group,
Let's be a finite simple group of order two
(Oughter: "Why not three?")

I've proved my proposition now, as you can see,
So let's both be associative and free
And by corollary, this shows you and I to be
Purely inseparable. Q.E.D.

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This is so amazing! – Sanath K. Devalapurkar Mar 26 '14 at 0:37

I received today this comment about a paper:

3 lines before section 2.1: A few typos: corresponds, 5-isogeny (I guess a 5-isogenie grants you five wishes?)

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a 5-isogenie grants you 5 identical wishes. – Michael Lugo Oct 19 '09 at 0:48

Based on the answers above, no.

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You can't refute an existential statement based on a finite number of nonexamples. – PyRulez Jan 13 '15 at 2:44

Q: How do you tell an extroverted mathematican from an introverted one?

A: An extroverted mathematician stares at your shoes when talking to you.

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This can be found in Steven Krantz's A Primer of Mathematical Writing, page 159 (footnote). The exact quote from there is: An introverted mathematician is one who looks at his shoes when he talks to you. An extroverted mathematician is one who looks at your shoes when he talks to you. – KConrad Apr 26 '11 at 0:31

Q: How many mathematicians does it take to change a light bulb?

A: One: she gives it to three physicists, thus reducing it to a problem that has already been solved.

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If somebody likes mathematical logic, category theory, lambda calculus, combinatory logic, then the following article can provide him/her jokes that are at the same time correct mathematical theorems:

Ruehr, Fritz (2001). The Evolution of a Haskell Programmer. Willamette University.

The article provides approaches to implement a mere Fibonacci function with such "over-calibrated" methods like harnessing deep metamathematical theorems (combinatory logic, category theory).

Haskell is a programming language (named after the logician Haskell B. Curry). It has been developed by academia (not by industry or market), and most motivations behind its creation was cleanness and purity. And it is based directly on lambda calculus, type theory, combinatory logic. Many of the programmer practice in it is based on category theory and algebra.

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I like this one:

A mathematican walks into a bar accompanied by a dog and a cow.
The bartender says, “Hey, no animals are allowed in here!”
The mathematician replies, “These are very special animals.”
“How so?”
“They’re knot theorists.”
The bartender raises his eyebrows and says, “I’ve met a number of knot theorists who I thought were animals, but never an animal that was a knot theorist.”
“Well, I’ll prove it to you. Ask them them anything you like.”
So the bartender asks the dog, “Name a knot invariant.”
“Arf! Arf!” barks the dog.
The bartender scowls and turns to the cow asking, “Name a topological invariant.”
“Mu! Mu!” says the cow.
At this point the bartender turns to the mathematican and says, “Very funny.” With that, he throws the three out of the bar.
Outside, sitting on the curb, the dog turns to the mathematican and asks, “Do you think I should have said the Jones polynomial instead?”

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which is the variant of the encient: "Who was the greatest baseball player that ever lived?" "Ruth!" barked the dog. "Okay, that's it!" says the bartender, and physically throws both man and dog out the door and onto the street. Turning to the man, the dogs shrugs and says, "Dimaggio?" – David Lehavi Oct 22 '09 at 18:38
You joke is due to Joel Hass, I believe. – Ryan Budney Nov 6 '09 at 21:09

Perhaps the question should be, not "Do good math jokes exist", but "are they unique"?

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I think there's only one isomorphism class of math joke. – userN Oct 19 '09 at 15:48
But sadly, it has non-trivial automorphisms. – Andrew Critch Dec 1 '09 at 10:42
Let's classify the category of math jokes. Is it additive? abelian? triangulated? tannakian? a topos? – David Corwin Dec 28 '12 at 6:25

I find the observation that the grade school carry operation from addition-with-carry forms a non-trivial degree 1 cocycle in the group cohomology of Z/10 a pretty good joke embedded in mathematics.

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Here's one I came up with a few years ago that I'm quite proud of.

Q: What do you get when you cross a chicken with an elephant?
A: The trivial elephant bundle on a chicken.

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I don't get that one. Explanations? – Randomblue Nov 26 '09 at 15:05
HAHAHA wakin' my neighbors laughing at this one... – Andrew Critch Dec 1 '09 at 10:58
@Justin: see . – Qiaochu Yuan Jun 10 '10 at 12:33
I heard this from Rob Easton (I think) several years ago, I also found it hilarious. Again, thank you. – Karl Schwede Oct 29 '10 at 2:35
What do you get when you cross a citrus fruit with a bull? The trivial lime bundle on a taurus. – Michael Albanese Jun 10 '13 at 12:28

Kurd Lasswitz, mathematician, writer, inventor of science fiction in Germany, wrote this "nth part of Faust" for the Breslau Mathematical Society 1882:

Prost, Stud. math. in höheren Semestern, steht vor dem Staats-Examen,
Mephisto, Dx (sprich De-ix), Differentialgeisterkönig, ein Fuchs.
Ort Breslau. Zeit: Nach dem Abendessen. (Rechts ein Sofa, auf dem Tische zwischen allerlei Büchern ein Bierseidel und Bierflaschen, links eine Tafel auf einem Gestell, Kreide und Schwamm. Auf der Tafel ist eine die gesamt Fläche einnehmende ungeheuerliche Differentialgleichung aufgeschrieben).

Prost am Tische, mit den Büchern beschäftigt. Er stärkt sich.


Habe nun, ach, Geometrie, Analysis und Algebra
und leider auch Zahlentheorie studiert,
und wie, das weiß man ja!
Da steh' ich nun als Kandidat
und finde zur Arbeit keinen Rat.
Ließe mich gern Herr Doktor lästern;
zieh' ich doch schon seit zwölf Semestern
herauf, herab und quer und krumm
meine Zeichen auf dem Papiere herum,
und seh', daß wir nichts integrieren können.
Es ist wahrhaftig zum Kopfeinrennen.

Zwar bin ich nicht so hirnverbrannt,
daß ich mich quälte als Pedant,
wenn ich 'ne Reihe potenziere,
zu seh'n, ob sie auch konvergiere,
... "

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A creation of my own:

Q:What did the simplicial set say to the fibrant replacement functor?

A:"Oh, I'm so horny..."

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As it would be impossible to prove that good math jokes don't exist I would have to say that the probability is better than zero.

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Ugh, why aren't these posted yet:

Q: What's purple and commutes? A: An Abelian grape.

Q: What's sour, yellow, and equivalent to the axiom of choice? A: Zorn's lemon.


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What's purple, commutes, and is worshipped twice a night? A bi-nightly venerated Abelian grape. The other answer to "what's purple and commutes?", for the Chicagoans and ex-Chicagoans out there, is "the Evanston Express". – Hugh Thomas Oct 19 '09 at 17:07
They are not posted because they are not good, maybe? :P – Mariano Suárez-Alvarez Nov 23 '09 at 5:36
Seen on a restroom wall in the Berkeley math dept.: What's brown and commutes? An abelian poop. – S. Carnahan Jun 22 '10 at 7:31

Quite a few mathematics / academic jokes here.

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A biologist, a physicist and a mathematician were all drinking coffee and tea and observing a house across the street from them. They notice that two people walk into the house and then an hour later, three people walk out.

Physicist: An experimental error. Our first measurement was incorrect.

Biologist: No, they've obviously reproduced.

Mathematician: No, now when a one person enters the house, it'll be empty again.

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A swiftie. Most of you are probably too young to remember them...

" $s = \displaystyle\int_a^b \sqrt{1 + [f'(x)]^2}\mathrm{d}x$ ", said Tom at length.

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Swifties were (and still are) published in the jokes section of "Boy's Life" (the official magazine for the Boy Scouts of America). I'm fairly young, but I know what they are! :) – apnorton Aug 22 '14 at 2:53

"Why did the chicken cross the Mobius band?"

The question isn't whether good math jokes exist, but whether they can be classified. The example above works because it plays on ones expectation of the "chicken crossing the road" jokes. Another one in the same vein, known as the shortest math joke:

"Let epsilon<0."

Another one, which I actually heard in class:

"Take a positive integer N. No wait, N is too big; take a positive integer k."

Here is a non-exhaustive classification of math jokes:

  • Puns on mathematical terminology
  • Mathematical reasoning in non-mathematical setting
  • Twists on expectations
  • Meta-jokes approached in a mathematical mode of enquiry

A joke can belong to more than one classification. For example, the "Dog and cow knot theorists" has both puns and a twist on expectations.

By the way, I would exclude jokes which are purely made on stereotypes, like the above joke on extrovert mathematician, because I don't find it funny.

I leave with one of my favorite meta-jokes:

"How many members of a certain demographic group does it take to perform a specified task? A finite number: one to perform the task and the remainder to act in a manner stereotypical of the group in question."

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The epsilon joke isn't funny. It would be funny if it read "epsilon <= 0". – Loop Space Oct 26 '09 at 7:23
Still don't get the epsilon joke, with or without =. – mathreader Dec 7 '09 at 4:24
The joke is that epsilon almost always stands for a small positive real constant, e.g. in the epsilon-delta definition of continuity. – Qiaochu Yuan Jun 10 '10 at 12:31
The classification provided by the meta-joke is quite precise :) – Pandora Jul 16 '10 at 14:51

An engineer hears that a famous mathematician will be giving a public lecture, and always having a soft spot for math, he attends. The mathematician then talks at length about all sorts of amazing phenomena that happen in 17 dimensional space. The engineer, amazed at this mathematician's intuition for 17 dimensional space, goes up to him afterwards and asks 'How do you picture 17 dimensions?", to which the mathematician answers 'Oh, its easy. Just imagine n-dimensional space, and set n equal to 17.'

My dad (an engineer) loves that joke.

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The spectral sequence is like the mini-skirt; it shows what is interesting while hiding the essential.

This saying is attributed to someone from Bourbaki in Bourbaki's Art of Memory.

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From an issue of How to Gamit (the MIT student manual) from the 1980s: a paper should be like a miniskirt: short enough to be interesting and long enough to cover the subject. – José Figueroa-O'Farrill Oct 27 '09 at 10:21
Just wondering: if you were wearing a skirt in the same room that somebody was saying one of these, how would you feel? The attributions to these jokes suggest that they are decades old, and it shows. In my opinion, these jokes should be left in those decades. – anon Apr 18 '11 at 0:08
@anon: I would feel like any other random person in the room. What is so inappropriate here? The indirect reference to one's genitalia or is it commenting on other people's garments? :) Or to turn it the other way round, how would you feel if you were a sexually frustrated heterosexual male whose class would be attended by attractive females in miniskirts? Is it appropriate to wear them but inappropriate to joke about these issues? Of course, every joke requires certain amount of tact, but on what grounds exactly are you condemning this one to times past? – Vít Tuček Jan 6 '14 at 16:28
@VítTuček When there is a very obvious power imbalance (eg men and women in STEM), then the approach that is most conducive to restoring balance is maybe to err on the side of not making jokes that might make the few (eg) women in the crowd uncomfortable. For lots of examples of people not doing this, see the tech industry, or google gamergate. – David Steinberg Oct 13 '15 at 17:29
@VítTuček Replace "miniskirt" with "speedo" and it becomes immediately evident that the remark is a sleazy innuendo "appreciating" a woman's genitalia, not unlike a street catcall. Please don't be so naive as to draw a comparison with nerd jokes or the alleged discomfort of sexually frustrated men in the presence of perfectly normally dressed women. – Elizabeth Henning Oct 24 '15 at 19:46

What did the zero say to the eight? "Nice belt."

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This joke isn't a math joke; it contains numbers. – user29225 Aug 10 '15 at 11:37

Here are a few of my own inventions:

Old Macdonald had a form; ei /\ ei = 0

Save the environment: use continuation passing style!

What shape of pasta takes the least time to eat? Brachistochroni!

You might be a mathematician if you think fog is a composition.

The Yoda embedding, contravariant it is.

How are Goethe's Faust novels like isomorphisms of sets? Dey're de monic epics.

I'm kind of in two minds about this whole Schroedinger's cat thing...

qwhine, n. self-recrimination

recursive: (λ damn. damn (damn)) (λ damn. damn (damn))

Coeschatology: the study of the beginning of times. The coend is ming!

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The first one is just awesome! Please keep inventing! – Armin Straub Oct 29 '09 at 15:33
the yoda joke is great!! – Martin Brandenburg Jan 17 '10 at 11:58
@Mike Goethe’s Fausts are not novels, but dramas. – The User Jul 11 '13 at 19:44
@Olga Mathematics is culture. – The User Jul 11 '13 at 19:45
I think you mean the ming is coending. – PyRulez Jan 13 '15 at 2:33

Mike's last joke reminded me of this one: a comathematician is a device for turning cotheorems into ffee.

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For a while I've been wondering what mbinatorics would be, if it existed. Presumably it would be useful for mputer science. – Michael Lugo Oct 25 '09 at 0:53
AJ Tolland is fond of saying that what we really need is a machine for turning some of those theorems back into coffee. – Noah Snyder Oct 27 '09 at 22:58
I disagree. Mputer science would be useful for mbinatorics, not the other way around. – Boris Bukh Oct 30 '09 at 22:44
Ribet once told me that he was sent a generic UG textbook by a publisher for free, with the suggestion that he use it in his UG course. He decided not to, and took the book to Black Oak Books (2nd hand book store in Berkeley) and sold it for a few $$. On the walk back to the department he bought some coffee with the money, and then realised to his amusement that he'd done precisely what Noah mentioned above. – Kevin Buzzard Nov 4 '09 at 11:24
I think I'm going to have to start referring to "cocoa" as "a". – Ian Morris Nov 24 '09 at 10:23

My favourite, from Eilenberg's obituary:

When someone once asked Professor Eilenberg if he could eat Chinese food with three chopsticks, he answered, "Of course," according to Professor Morgan. The questioner asked, "How are you going to do it?" and Professor Eilenberg replied, "I'll take the three chopsticks, I'll put one of them aside on the table, and I'll use the other two."

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An engineer, a physicist and a mathematician are driving through the high country in Scotland. Atop a hill, they see a black sheep.

The engineer says: "All sheep are black!" The physicist says: "No, no, some sheep are black." The mathematician: "At least one sheep is black on at least one side."

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