Characterizing the NP-PSPACE Gap in the Satisfiability Problem for Modal Logic.

Joseph Y. Halpern Leandro Chaves Rêgo Characterizing the NP-PSPACE Gap in the Satisfiability Problem for Modal Logic. 795-806 2007 17 J. Log. Comput. 4 http://dx.doi.org/10.1093/logcom/exm029 db/journals/logcom/logcom17.html#HalpernR07