Orna Grumberg Flavio Lerda Ofer Strichman Michael Theobald Proof-guided underapproximation-widening for multi-process systems. 122-131 2005 conf/popl/2005 POPL http://doi.acm.org/10.1145/1040305.1040316 db/conf/popl/popl2005.html#GrumbergLST05