Kai Engelhardt Ron van der Meyden Yoram Moses A Refinement Theory that Supports Reasoning About Knowledge and Time. 125-141 2001 conf/lpar/2001 LPAR http://link.springer.de/link/service/series/0558/bibs/2250/22500125.htm db/conf/lpar/lpar2001.html#EngelhardtMM01