Characterizing the NP-PSPACE Gap in the Satisfiability Problem for Modal Logic
Abstract
There has been a great deal of work on characterizing the complexity of the satisfiability and validity problem for modal logics. In particular, Ladner showed that the satisfiability problem for all logics between K and S4 is PSPACE-hard, while for S5 it is NP-complete. We show that it is negative introspection, the axiom ¬Kp ⇒ K¬Kp, that causes the gap: if we add this axiom to any modal logic between K and S4, then the satisfiability problem becomes NP-complete. Indeed, the satisfiability problem is NP-complete for any modal logic that includes the negative introspection axiom.
Cite
Text
Halpern and Rêgo. "Characterizing the NP-PSPACE Gap in the Satisfiability Problem for Modal Logic." International Joint Conference on Artificial Intelligence, 2007. doi:10.1093/logcom/exm029Markdown
[Halpern and Rêgo. "Characterizing the NP-PSPACE Gap in the Satisfiability Problem for Modal Logic." International Joint Conference on Artificial Intelligence, 2007.](https://mlanthology.org/ijcai/2007/halpern2007ijcai-characterizing-a/) doi:10.1093/logcom/exm029BibTeX
@inproceedings{halpern2007ijcai-characterizing-a,
title = {{Characterizing the NP-PSPACE Gap in the Satisfiability Problem for Modal Logic}},
author = {Halpern, Joseph Y. and Rêgo, Leandro Chaves},
booktitle = {International Joint Conference on Artificial Intelligence},
year = {2007},
pages = {2306-2311},
doi = {10.1093/logcom/exm029},
url = {https://mlanthology.org/ijcai/2007/halpern2007ijcai-characterizing-a/}
}