Edd Turner Michael Leuschel Corinna Spermann Michael J. Butler Symmetry Reduced Model Checking for B. 25-34 2007 conf/tase/2007 TASE http://doi.ieeecomputersociety.org/10.1109/TASE.2007.50 db/conf/tase/tase2007.html#TurnerLSB07