# Mike Shor: Humor

### How To Prove It

- 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 intimidation:
- "Trivial."
- proof by vigorous handwaving:
- Works well in a classroom or seminar setting.
- 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 omission:
- "The reader may easily supply the details"

"The other 253 cases are analogous"

"..." - 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 funding:
- How could three different government agencies be wrong?
- 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 picture:
- A more convincing form of proof by example. Combines well with proof by omission.
- 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 forward reference:
- Reference is usually to a forthcoming paper of the author, which is often not as forthcoming as at first.
- 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.