Michael Huth Nir Piterman Daniel Wagner Three-Valued Abstractions of Markov Chains: Completeness for a Sizeable Fragment of PCTL. 205-216 2009 FCT http://dx.doi.org/10.1007/978-3-642-03409-1_19 conf/fct/2009 db/conf/fct/fct2009.html#HuthPW09