Q: Why did the chicken cross the Moebius strip?
A: To get to the other... er, um...


Q: What do you get when you cross an elephant and a banana?
A: |elephant| * |banana| * sin(theta)


Q: Why didn't Newton discover group theory?
A: Because he wasn't Abel.


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


Q: What is the difference between a PhD in mathematics and a large pizza?
A: A large pizza can feed a family of four.


Q: How can you tell that a mathematician is extroverted?
A: When he talks to you, he looks at your shoes instead of at his.


Q: Why do mathematicians often confuse Christmas and Halloween?
A: Because Oct 31 = Dec 25.

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A topologist is someone who doesn't know his ass from a hole in the ground.

A statistician is someone who is good with numbers but lacks the personality to be an accountant.

A mathematician is asked by a friend who is a devout Christian: "Do you believe in one God?" He answers: "Yes - up to isomorphism."

Three statisticians go hunting. When they see a rabbit, the first one shoots, missing it on the left. The second one shoots and misses it on the right. The third one shouts: "We've hit it!"

Computer Science student: "My computer ate my data, it's trying to get me in trouble."
CS Instructor: "Don't anthropomorphize computers, they don't like that."


There were three medieval kingdoms on the shores of a lake. There was an island in the middle of the lake, over which the kingdoms had been fighting for years. Finally, the three kings decided that they would send their knights out to do battle, and the winner would take the island. The night before the battle, the knights and their squires pitched camp and readied themselves for the fight. The first kingdom had 12 knights, and each knight had five squires, all of whom were busily polishing armor, brushing horses, and cooking food. The second kingdom had twenty knights, and each knight had 10 squires. Everyone at that camp was also busy preparing for battle. At the camp of the third kingdom, there was only one knight, with his squire. This squire took a large pot and hung it from a looped rope in a tall tree. He busied himself preparing the meal, while the knight polished his own armor. When the hour of the battle came, the three kingdoms sent their squires out to fight (this was too trivial a matter for the knights to join in). The battle raged, and when the dust had cleared, the only person left was the lone squire from the third kingdom, having defeated the squires from the other two kingdoms, thus proving that the squire of the high pot and noose is equal to the sum of the squires of the other two sides.


When Noah's ark had finally come to a rest on top of mount Ararat, and when the waters had receded, Noah and his family - along with all the animals - left the ark, and God told them to be fruitful and multiply upon the earth. But after all those months under deck on an overcrowded ark, none of the animals was in the mood for sex anymore. Noah, who knew all too well what God could do in his wrath if his creatures were disobedient, got desperate. So, he tore down one of the ark's masts, cut it into pieces, and built a table out of the logs. Then he told one of the snakes to perform a lascivious dance on top of the table and made all the other animals gather around it. After a while the snake's seductive moves showed an effect: One animal after the other started rocking in the rhythm of the snake's dance, and one after the other sneaked off with its mate to more private places... Finally, the dancing snake and her mate were all alone, and they too disappeared. And Noah was pleased that God's will would be heeded.
Q: What does this story from the book of Genesis teach us about math?
A: When you have to multiply, all you need are a log table and an adder!


A stats professor plans to travel to a conference by plane. When he passes the security check, they discover a bomb in his carry-on-baggage. Of course, he is hauled off immediately for interrogation. "I don't understand it!" the interrogating officer exclaims. "You're an accomplished professional, a caring family man, a pillar of your parish - and now you want to destroy that all by blowing up an airplane!" "Sorry", the professor interrupts him. "I had never intended to blow up the plane." "So, for what reason else did you try to bring a bomb on board?!" "Let me explain. Statistics shows that the probability of a bomb being on an airplane is 1/1000. That's quite high if you think about it - so high that I wouldn't have any peace of mind on a flight." "And what does this have to do with you bringing a bomb on board of a plane?" "You see, since the probability of one bomb being on my plane is 1/1000, the chance that there are two bombs is 1/1000000. If I already bring one, the chance of another bomb being around is actually 1/1000000, and I am much safer.


A graduate student of mathematics who used to come to the university on foot every day arrives one day on a fancy new bicycle. "Where did you get the bike from?" his friends want to know. "It's a `thank you' present", he explains, "from that freshman girl I've been tutoring. But the story is kind of weird..." "Tell us!" "Well", he starts, "yesterday she called me on the phone and told me that she had passed her math final and that she wanted to drop by to thank me in person. As usual, she arrived at my place riding her bicycle. But when I had let her in, she suddenly took all her clothes off, lay down on my bed, smiled at me, and said: 'You can get from me whatever you desire!'" One of his friends remarks: "You made a really smart choice when you took the bicycle." "Yeah", another friend adds, "just imagine how silly you would have looked in a girl's clothes - and they wouldn't have fit you anyway!"


A physicist, a statistician, and a (pure) mathematician go to the races and place bets on horses. The physicist's horse comes in last. "I don't understand it. I have determined each horse's strength through a series of careful measurements." The statistician's horse does a little bit better, but still fails miserably. "How is this possible? I have statistically evaluated the results of all races for the past month." They both look at the mathematician whose horse came in first. "How did you do it?" "Well", he explains. "First, I assumed that all horses were identical and spherical..."


An engineer, a physicist and a mathematician are staying in a hotel. The engineer wakes up and smells smoke. He goes out into the hallway and sees a fire, so he fills a trash can from his room with water and douses the fire. He goes back to bed. Later, the physicist wakes up and smells smoke. He opens his door and sees a fire in the hallway. He walks down the hall to a fire hose and after calculating the flame velocity, distance, water pressure, trajectory, etc. extinguishes the fire with the minimum amount of water and energy needed. Later, the mathematician wakes up and smells smoke. He goes to the hall, sees the fire and then the fire hose. He thinks for a moment and then exclaims, "Ah, a solution exists!" and then goes back to bed.


There was once a very smart horse. Anything that was shown it, it mastered easily, until one day, its teachers tried to teach it about rectangular coordinates and it couldn't understand them. All the horse's acquaintances and friends tried to figure out what was the matter and couldn't. Then a new guy looked at the problem and said, "Of course he can't do it. Why, you're putting Descartes before the horse!"


A combinatorist and his friend are sitting on a train when they pass by a cattle ranch just teeming with cattle. "Look at all those cows," the friend says. "I wonder how many there are." The combinatorist glances out the window for a second and says "There's 1734 cows." His friend is stunned. "You're kidding... did you really count all those cows!?!?" "Of course not, that's ridiculous. I just counted all the legs and divided by 4."


A biologist, a physicist and a mathematician were sitting in a street cafe watching the crowd. Across the street they saw a man and a woman entering a building. Ten minutes they reappeared together with a third person.
- They have multiplied, said the biologist.
- Oh no, an error in measurement, the physicist sighed.
- If exactly one person enters the building now, it will be empty again, the mathematician concluded.

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Proof Methods:

Proof by vigorous handwaving:
    Works well in a classroom or seminar setting.
Proof by forward reference:
    Reference is usually to a forthcoming paper of the author, which is often not as forthcoming as at first.
Proof by funding:
    How could three different government agencies be wrong?
Proof by example:
    The author gives only the case n = 2 and suggests that it contains most of the ideas of the general proof.
Proof by omission:
    "The reader may easily supply the details" or "The other 253 cases are analogous"
Proof by deferral:
    "We'll prove this later in the course".
Proof by picture:
    A more convincing form of proof by example. Combines well with proof by omission.
Proof by intimidation:
    "Trivial."
Proof by adverb:
    "As is quite clear, the elementary aforementioned statement is obviously valid."
Proof by seduction:
    "Convince yourself that this is true!"
Proof by cumbersome notation:
    Best done with access to at least four alphabets and special symbols.
Proof by exhaustion:
    An issue or two of a journal devoted to your proof is useful.
Proof by obfuscation:
    A long plotless sequence of true and/or meaningless syntactically related statements.
Proof by wishful citation:
    The author cites the negation, converse, or generalization of a theorem from the literature to support his claims.
Proof by eminent authority:
    "I saw Karp in the elevator and he said it was probably NP-complete."
Proof by personal communication:
    "Eight-dimensional colored cycle stripping is NP-complete [Karp, personal communication]."
<>Proof by reduction to the wrong problem:
    "To see that infinite-dimensional colored cycle stripping is decidable, we reduce it to the halting problem."
Proof by reference to inaccessible literature:
    The author cites a simple corollary of a theorem to be found in a privately circulated memoir of the Slovenian Philological Society, 1883.
Proof by importance:
    A large body of useful consequences all follow from the proposition in question.
Proof by accumulated evidence:
    Long and diligent search has not revealed a counterexample.
Proof by cosmology:
    The negation of the proposition is unimaginable or meaningless. Popular for proofs of the existence of God.
Proof by mutual reference:
    In reference A, Theorem 5 is said to follow from Theorem 3 in reference B, which is shown to follow from Corollary 6.2 in reference C, which is an easy consequence of Theorem 5 in reference A.
Proof by metaproof:
    A method is given to construct the desired proof. The correctness of the method is proved by any of these techniques.
Proof by vehement assertion:
    It is useful to have some kind of authority relation to the audience.
Proof by ghost reference:
    Nothing even remotely resembling the cited theorem appears in the reference given.
Proof by semantic shift:
    Some of the standard but inconvenient definitions are changed for the statement of the result.
Proof by appeal to intuition:
    Cloud-shaped drawings frequently help here.

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Salary Theorem
The less you know, the more you make.

Proof:
Postulate 1: Knowledge is Power.
Postulate 2: Time is Money.

As every engineer knows: Power = Work / Time.
And since Knowledge = Power and Time = Money, it is therefore true that Knowledge = Work / Money.
Solving for Money, we get: Money = Work / Knowledge. Thus, as Knowledge approaches zero, Money approaches infinity, regardless of the amount of Work done.

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How we do it:

Computer scientists do it depth-first.
Galois theorists do it in a field.
Linear programmers do it with nearest neighbors.
Logicians do it incompletely or inconsistently.
Set theorists do it with cardinals.
Markov does it in chains.
Fermat tried to do it in the margin, but couldn't fit it in.
Analysts do it continuously.