On the Regular Emptiness Problem of Subzero Automata
  Subzero automata is a class of tree automata whose acceptance condition can express probabilistic constraints. Our main result is that the problem of determining if a subzero automaton accepts some regular tree is decidable. 
Henryk Michalewski (University of Warsaw, Poland), Matteo Mio (CNRS   and ENS-Lyon, France), Miko{\l}aj Boja\'nczyk (Univers...
cs.FL cs.LO