# How to Prove It (humor)

**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.