The Cut Elimination and the Nonlengthening Property for the Sequent Calculus with Equality

Abstract

We show how Leibnitz.s indiscernibility principle and Gentzen's original work lead to extensions of the sequent calculus to first order logic with equality and investigate the cut elimination property. Furthermore we discuss and improve the nonlengthening property of Lifshitz and Orevkov.

arXiv comment30 pages Presented to Logic Colloquium 2016 (Leeds)