Font, Josep M.Moussavi, Massoud2020-03-042020-03-041990https://hdl.handle.net/2445/151957Preprint enviat per a la seva publicació en una revista científica: Journal of Applied Non-Classical Logics. Volume 3, 1993 - Issue 2, pp:173-187. [https://doi.org/10.1080/11663081.1993.10510806]In this paper we introduce a set of six logical values, which arises in the application of three-valued logics to time intervals, find its algebraic structure, and use it to define a six-valued logic. We then prove, by using algebraic properties of the class of De Morgan algebras, that this semantically defined logic can be axiomatized as Belnap's "useful" four-valued logic. Other directions of research suggested by the construction of this set of six logical values are described.13 p.application/pdfeng(c) Josep M. Font et al., 1990Lògica matemàticaLògica algebraicaTeoria dels reticlesIntel·ligència artificialUniversitat de Barcelona. Institut de Matemàticainfo:eu-repo/semantics/articleinfo:eu-repo/semantics/openAccess