Proof by example: The author gives only
the case n = 2 and suggests that it contains most of the ideas
Take a break from the drudgery with some of these jokes, song parodies, anecdotes and assorted humor that has been
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of the general proof.
Proof by vigorous hand-waving: Works well in a classroom or seminar
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
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
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
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
memoir of the Slovenian Philological
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
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
Proof by appeal to intuition:
Cloud-shaped drawings frequently help here. The above material is by Dana Angluin and
was published in Sigact News, Winter-Spring, 1983, Volume 15 #1.