Jean Goubault-Larrecq Simulation Hemi-metrics between Infinite-State Stochastic Games. 50-65 2008 FoSSaCS http://dx.doi.org/10.1007/978-3-540-78499-9_5 conf/fossacs/2008 db/conf/fossacs/fossacs2008.html#Goubault-Larrecq08