A four-valued modal logic arising from Monteiro's last algebras
Josep Maria Font, Miquel Rius · 2002
The class of abstract logics projectively generated by the class of logics defined on tetravalent modal algebras by the family of their filters is studied. These logics are four-valued in the sense that they can be characterized by a generalized matrix on the four-element tetravalent modal algebra which generates this variety together with a family of homomorphisms. They can be called modal since this four-element algebra can be given a nice epistemic interpretation as an extension of Belnap's four-valued logic. The authors also characterize them by their abstract properties and prove a completeness theorem with respect to a sequent calculus suggested by the abstract version.>