• Media type: E-Article
  • Title: Derivation Rules as Anti-Axioms in Modal Logic
  • Contributor: Venema, Yde
  • imprint: Association for Symbolic Logic, Inc., 1993
  • Published in: The Journal of Symbolic Logic
  • Language: English
  • ISSN: 0022-4812
  • Origination:
  • Footnote:
  • Description: <p>We discuss a `negative' way of defining frame classes in (multi)modal logic, and address the question of whether these classes can be axiomatized by derivation rules, the `non-ξ rules', styled after Gabbay's Irreflexivity Rule. The main result of this paper is a metatheorem on completeness, of the following kind: If Λ is a derivation system having a set of axioms that are special Sahlqvist formulas and Λ⁺ is the extension of Λ with a set of non-ξ rules, then Λ⁺ is strongly sound and complete with respect to the class of frames determined by the axioms and the rules.</p>