HOW TO PROVE IT, PART 5
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.

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