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Unsound Inferences Make Proofs Shorter (1608.07703v2)
Published 27 Aug 2016 in math.LO and cs.LO
Abstract: We give examples of calculi that extend Gentzen's sequent calculus LK by unsound quantifier inferences in such a way that (i) derivations lead only to true sequents, and (ii) proofs therein are non-elementarily shorter than LK-proofs.