Cut elimination for Zermelo set theory

Gilles Dowek; Alexandre Miquel

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arXiv · 2310.20253

Cut elimination for Zermelo set theory

Gilles Dowek·Alexandre Miquel

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Abstract

We show how to express intuitionistic Zermelo set theory in deduction modulo (i.e. by replacing its axioms by rewrite rules) in such a way that the corresponding notion of proof enjoys the normalization property. To do so, we first rephrase set theory as a theory of pointed graphs (following a paradigm due to P. Aczel) by interpreting set-theoretic equality as bisimilarity, and show that in this setting, Zermelo's axioms can be decomposed into graph-theoretic primitives that can be turned into rewrite rules. We then show that the theory we obtain in deduction modulo is a conservative extension of (a minor extension of) Zermelo set theory. Finally, we prove the normalization of the intuitionistic fragment of the theory.

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Gilles Dowek, Alexandre Miquel. 2023-10-31. Cut elimination for Zermelo set theory. https://arxiv.org/abs/2310.20253

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