Proof Techniques. (author unknown)

This is a list of proof techniques which are very powerful, but unfortunately not valid. -- from a copy posted on unknown professor's door.

1. 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 analagous."

   "..."

   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 dilligent 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 the first.

   Proof by semantic shift :
   

   Some standard but inconvenient definitions are changed for the statement of the result.

   Proof by appeal to intuition :
   

   Cloud-shaped drawings frequently help here.