A note on Sugihara algebras

Abstract

In [41 Blok and Pigozzi prove syntactically that RM, the propositional calculus also called R-Mingle, is algebraizable, .and as a consequence there is a unique quasivariety (the so-called equivalent quasivariety semantics) associated to it . In [3] it is stated that this quasivariety is the variety of Sugihara algebras . Starting from this fact, in this paper we present an equational base for this variety obtained as a subvariety of the variety of R-algebras, found in [7] to be associated in the same sense to the calculus Rof relevance logic, and we determine the totally ordered, the subdirectly irreducible, and the simple members of this variety, by using some consequences of the algebraizability of the logic RM (R-Mingle) with which they are associated .