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Intuitionistic Existential Instantiation and Epsilon Symbol (1208.0861v1)
Published 3 Aug 2012 in math.LO and cs.LO
Abstract: A natural deduction system for intuitionistic predicate logic with existential \ instantiation rule presented here uses Hilbert's $\e$-symbol. It is conservative over intuitionistic predicate logic. We provide a completeness proof for a suitable Kripke semantics, sketch an approach to a normalization proof, survey related work and state some open problems. Our system extends intuitionistic systems with $\e$-symbol due to A. Dragalin and Sh. Maehara.