XCB, the Last of the Shortest Single Axioms for the Classical Equivalential Calculus

TitleXCB, the Last of the Shortest Single Axioms for the Classical Equivalential Calculus
Publication TypeReport
Year of Publication2002
AuthorsWos, L, Ulrich, D, Fitelson, B
Series TitleBull. Section Logic
Pagination120-134
Date Published06/2002
Other NumbersANL/MCS-P966-0602
Abstract

It has long been an open question whether the formula XCB = EpEEEpqErqr is, with the rules of substitution and detachment, a single axiom for the classical equivalential calculus. This paper answers that question affirmatively, thus completing a search for all such eleven-symbol single axioms that began seventy years ago.

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