Several characterizations of the 4–valued modal algebras

Aldo Victorio Figallo, Paolo Landini


A. Monteiro, in 1978, defined the algebras he named tetravalent
modal algebras,  that will be called  {\em $4-$valued modal
algebras} in this work. These algebras constitute a generalization of the $3-$valued Lukasiewicz algebras defined by Moisil.

The theory of the $4-$valued modal algebras has been widely developed by I. Loureiro in \cite{IL1, IL2, IL3, IL4, IL5, IL6, IL7} and by A. V. Figallo in \cite{FI3, FI4, AF.PL,AF.AZ}.

J. Font and M. Rius indicated, in the introduction to the important work \cite{JF.MR2}, a brief but detailed review on the $4-$valued modal algebras.

In this work varied characterizations are presented that show the ``closeness'' this variety of algebras has with other well--known algebras related to the algebraic counterparts of certain logics.

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