Rosser's trick

Etymology
Introduced by J. Barkley Rosser in 1936.

Proper noun

 * 1)  A method for proving Gödel's incompleteness theorems without the assumption that the theory being considered is ω-consistent. While Gödel's original proof uses a sentence that states (informally) "This sentence is not provable", Rosser's trick uses a formula that says "If this sentence is provable, there is a shorter proof of its negation".