Petr Jancar Antonín Kucera Faron Moller Zdenek Sawa DP lower bounds for equivalence-checking and model-checking of one-counter automata. 1-19 2004 188 Inf. Comput. 1 http://dx.doi.org/10.1016/S0890-5401(03)00171-8 db/journals/iandc/iandc188.html#JancarKMS04