Résumé | The first part of my talk will be about bisimilarity of one-counter automata (which are pushdown automata over a singleton stack symbol with a bottom-of-stack symbol). I will show that this problem is PSPACE-complete, improving the previously best-known 3-EXPSPACE upper bound by Yen (joint work with Stanislav Böhm and Petr Jancar).
The second part of the talk will be about the complexity of bisimilarity checking of pushdown automata. While decidability of this problem has been shown by Sénizergues, no complexity-theoretic upper bound of this problem is known to date. I will present a recent nonelementary lower bound for this problem, improving the previously best-known EXPTIME-hardness result of Kucera and Mayr (joint work with Michael Benedikt, Stefan Kiefer and Andrzej Murawski). |