@conference {4308, title = {Finite-valued Lukasiewicz modal logic is PSPACE-complete}, booktitle = {Twenty-second International Joint Conference on Artificial Intelligence (IJCAI 2011)}, year = {2011}, month = {16/07/2011}, pages = {774 - 779}, address = {Barcelona}, abstract = {It is well-known that satisfiability (and hence validity) in the minimal classical modal logic is a PSPACE-complete problem. In this paper we consider the satisfiability and validity problems (here they are not dual, although mutually reducible) for the minimal modal logic over a finite Lukasiewicz chain, and show that they also are PSPACE-complete. This result is also true when adding either the Delta operator or truth constants in the language, i.e. in all these cases it is PSPACE- complete.}, isbn = {978-1-57735-516-8}, author = {F{\`e}lix Bou and Marco Cerami and Francesc Esteva} }