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arXiv · 0806.1281

Extracting Programs from Constructive HOL Proofs via IZF Set-Theoretic Semantics

Robert Constable·Wojciech Moczydlowski
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Abstract

Church's Higher Order Logic is a basis for influential proof assistants -- HOL and PVS. Church's logic has a simple set-theoretic semantics, making it trustworthy and extensible. We factor HOL into a constructive core plus axioms of excluded middle and choice. We similarly factor standard set theory, ZFC, into a constructive core, IZF, and axioms of excluded middle and choice. Then we provide the standard set-theoretic semantics in such a way that the constructive core of HOL is mapped into IZF. We use the disjunction, numerical existence and term existence properties of IZF to provide a program extraction capability from proofs in the constructive core. We can implement the disjunction and numerical existence properties in two different ways: one using Rathjen's realizability for IZF and the other using a new direct weak normalization result for IZF by Moczydlowski. The latter can also be used for the term existence property.

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Robert Constable, Wojciech Moczydlowski. 2008-09-09. Extracting Programs from Constructive HOL Proofs via IZF Set-Theoretic Semantics. https://doi.org/10.2168/lmcs-4(3%3A5)2008

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