Interpolation above S4
Logic
2026-04-27 v1 Logic in Computer Science
Abstract
We complete Maksimova's classification of the normal extensions of S4 with interpolation. In particular, we prove Craig interpolation for the six extensions of S4 for which Craig interpolation was still open. The proof strategy builds upon the ideas of Smory\'nski, but employs a novel approach using Fine's frame formulas for splitting clusters.
Keywords
Cite
@article{arxiv.2604.22020,
title = {Interpolation above S4},
author = {Simon Santschi and Niels C. Vooijs},
journal= {arXiv preprint arXiv:2604.22020},
year = {2026}
}
Comments
15 pages, 2 figures, 2 tables