March 2011 On the non-confluence of cut-elimination
Matthias Baaz, Stefan Hetzl
J. Symbolic Logic 76(1): 313-340 (March 2011). DOI: 10.2178/jsl/1294171002

Abstract

We study cut-elimination in first-order classical logic. We construct a sequence of polynomial-length proofs having a non-elementary number of different cut-free normal forms. These normal forms are different in a strong sense: they not only represent different Herbrand-disjunctions but also differ in their propositional structure.

This result illustrates that the constructive content of a proof in classical logic is not uniquely determined but rather depends on the chosen method for extracting it.

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Matthias Baaz. Stefan Hetzl. "On the non-confluence of cut-elimination." J. Symbolic Logic 76 (1) 313 - 340, March 2011. https://doi.org/10.2178/jsl/1294171002

Information

Published: March 2011
First available in Project Euclid: 4 January 2011

zbMATH: 1220.03048
MathSciNet: MR2791350
Digital Object Identifier: 10.2178/jsl/1294171002

Rights: Copyright © 2011 Association for Symbolic Logic

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Vol.76 • No. 1 • March 2011
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