English

Finite axiomatization of $\textbf{GL}\times\textbf{S5}$ and $\textbf{Grz}\times\textbf{S5}$

Logic 2025-12-25 v4

Abstract

We prove that GL×S5\mathbf{GL} \times \mathbf{S5} is product matching, and that Grz×S5\mathbf{Grz} \times \mathbf{S5} is axiomatizable by adding to [Grz,S5][\mathbf{Grz},\mathbf{S5}] the G\"odel translation of the monadic Casari formula. This settles the question of the finite axiomatizability of these logics posed by Gabbay and Shehtman (1998).

Keywords

Cite

@article{arxiv.2512.09381,
  title  = {Finite axiomatization of $\textbf{GL}\times\textbf{S5}$ and $\textbf{Grz}\times\textbf{S5}$},
  author = {Guram Bezhanishvili and Mashiath Khan},
  journal= {arXiv preprint arXiv:2512.09381},
  year   = {2025}
}