Zhifu Zhang Nathan R. Sturtevant Robert C. Holte Jonathan Schaeffer Ariel Felner A* Search with Inconsistent Heuristics. 634-639 2009 IJCAI http://ijcai.org/papers09/Papers/IJCAI09-111.pdf conf/ijcai/2009 db/conf/ijcai/ijcai2009.html#ZhangSHSF09