Matteo Pradella Angelo Morzenti Pierluigi San Pietro The symmetry of the past and of the future: bi-infinite time in the verification of temporal properties. 312-320 2007 conf/sigsoft/2007 ESEC/SIGSOFT FSE http://doi.acm.org/10.1145/1287624.1287669 db/conf/sigsoft/fse2007.html#PradellaMP07