Abstract
We give an overview over several recent results about the complexity of checking weak and strong bisimulation equivalence on pushdown automata (PDA) and their subclass BPA. The focus of the talk will be on the general proof techniques used to achieve these results. In particular we'll discuss the following results:

1. The undecidability of weak bisimilarity for PDA. (Shown by Srba in CONCUR 2002).

2. The EXPTIME lower bound for strong bisimilarity on PDA. (Shown by Kucera and Mayr in MFCS 2002).

3. The complexity of comparing PDA to finite-state systems (PSPACE-complete for PDA; polynomial for BPA). (Kucera, Mayr)

Welcome

       Parosh Abdulla

ASTEC seminar
September 23, 2002

Place: Information technology, Uppsala University
Room: 1145
Time: 15.15-16.00 (+ discussions)

Room 1145 is in building 1, floor 1, room 13 (in the northern part of the building).

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There will be an extended period for discussions after the seminar.

Speakers are encouraged to give an short (5 min) introduction to the subject at the begining of the talk.
Listeners are excused if they have to leave after 16.00.