Download PDFOpen PDF in browserTwo-layer modal logics: from fuzzy logics to a general framework5 pages•Published: July 28, 2014AbstractThe idea of two-layer modal logics is inspired by the treatment of probability inside mathematical fuzzy logic, pioneered by Hajek and recentlystudied by numerous authors in numerous papers. Such logics are used in order to deal with a certain property of formulas of the base logic using a suitable `upper' logic (the seminal example being the probability of classical events formalized inside Lukasiewicz logic). The primary aim of this paper is to provide a new general framework for two-layer modal logics that encompasses the current state of the art and paves the way for future development. Diverting for the area of mathematical fuzzy logic, we show how one can construct such modal logic over an arbitrary non-classical logic (under certain technical requirements) with a modality interpreted by an arbitrary measure. We equip the resulting logics with a semantics of measured Kripke frames and prove corresponding completeness theorems. As an illustration of our results, we reprove Hajek's completeness result for Fuzzy Probability logic over Lukasiewicz logic. Keyphrases: fuzzy logic, modal logic, two level syntax In: Nikolaos Galatos, Alexander Kurz and Constantine Tsinakis (editors). TACL 2013. Sixth International Conference on Topology, Algebra and Categories in Logic, vol 25, pages 43-47.
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