2024/12/14 by Bezhanishvili, Guram, Khan, Mashiath · 2 citations
#03B45 #03C90 #06E25 #FOS: Mathematics #Logic (math.LO)
paper · doi:10.48550/arxiv.2412.10854
We develop a semantic criterion for determining whether a given monadic modal logic axiomatizes the one-variable fragment of a predicate modal logic. We show that the criterion applies to the monadic Grzegorczyk logic MGrz, thus establishing that MGrz axiomatizes the one-variable fragment of the predicate Grzegorczyk logic QGrz. This we do by proving the finite model property of MGrz, which is achieved by strengthening the notion of a maximal point of a descriptive MGrz-frame and by refining the existing selective filtration methods.