Density Elimination and Rational Completeness for First-Order Logics
نویسندگان
چکیده
Density elimination by substitutions is introduced as a uniformmethod for removing applications of the Takeuti-Titani density rule from proofs in firstorder hypersequent calculi. For a large class of calculi, density elimination by this method is guaranteed by known sufficient conditions for cut-elimination. Moreover, adding the density rule to any axiomatic extension of a simple first-order logic gives a logic that is rational complete; i.e., complete with respect to linearly and densely ordered algebras: a precursor to showing that it is a fuzzy logic (complete for algebras with a real unit interval lattice reduct). Hence the sufficient conditions for cut-elimination guarantee rational completeness for a large class of first-order substructural logics.
منابع مشابه
Density Elimination 1
Density elimination, a close relative of cut elimination, consists of removing applications of the Takeuti-Titani density rule from derivations in Gentzen-style (hypersequent) calculi. Its most important use is as a crucial step in establishing standard completeness for syntactic presentations of fuzzy logics; that is, completeness with respect to algebras based on the real unit interval [0, 1]...
متن کاملFirst-order t-norm based fuzzy logics with truth-constants: Distinguished semantics and completeness properties
This paper aims at being a systematic investigation of different completeness properties of first-order predicate logics with truth-constants based on a large class of left-continuous t-norms (mainly continuous and weak nilpotent minimum t-norms). We consider standard semantics over the real unit interval but also we explore alternative semantics based on the rational unit interval and on finit...
متن کاملDistinguished algebraic semantics for t-norm based fuzzy logics: Methods and algebraic equivalencies
This paper is a contribution to the algebraic study of t-norm based fuzzy logics. In the general framework of propositional core and ∆-core fuzzy logics we consider three properties of completeness with respect to any semantics of linearly ordered algebras. Useful algebraic characterizations of these completeness properties are obtained and their relations are studied. Moreover, we concentrate ...
متن کاملElimination of Cuts in First-order Finite-valued Logics
A uniform construction for sequent calculi for finite-valued first-order logics with distribution quantifiers is exhibited. Completeness, cut-elimination and midsequent theorems are established. As an application, an analog of Herbrand’s theorem for the four-valued knowledgerepresentation logic of Belnap and Ginsberg is presented. It is indicated how this theorem can be used for reasoning about...
متن کاملTableau Proof Systems for Justification Logics
In this paper we present tableau proof systems for various justification logics. We show that the tableau systems are sound and complete with respect to Mkrtychev models. In order to prove the completeness of the tableaux, we give a syntactic proof of cut elimination. We also show the subformula property for our tableaux.
متن کامل