Frédéric Herbreteau B. Srivathsan Igor Walukiewicz Efficient Emptiness Check for Timed Büchi Automata. 148-161 2010 CAV https://doi.org/10.1007/978-3-642-14295-6_15 conf/cav/2010 db/conf/cav/cav2010.html#HerbreteauSW10