Proof Theory of Finite-Valued Logics

Zach, Richard. 1993. “Proof Theory of Finite-Valued Logics.” Diplomarbeit, Vienna, Austria: Technische Universität Wien. DOI: 10.11575/PRISM/38803

Several people have, since the 1950’s, proposed ways to generalize proof theoretic formalisms (sequent calculus, natural deduction, resolution) from the classical to the many-valued case. One particular method for systematically obtaining calculi for all finite-valued logics was invented independently by several researchers, with slight variations in design and presentation. The main aim of this report is to develop the proof theory of finite-valued first order logics in a general way, and to present some of the more important results in this area. This report is actually a template, from which all results can be specialized to particular logics.

The main results of this report are: the use of signed formula expressions and partial normal forms to provide a unifying framework in which clause translation calculi, sequent calculi, natural deduction, and also tableaux can be represented; bounds for partial normal forms for general and induced quantifiers; and negative resolution. The cut-elimination theorems extend previous results, and the midsequent theorem, natural deduction systems for many-valued logics as well as results on approximation of axiomatizable propositional logics by many-valued logics are all new.

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