Short Witnesses and Accepting Lassos in omega-automata – Author’s Notes & Erratum

This page contains some additional information to the paper “Short Witnesses and Accepting Lassos in omega-automata” by Rüdiger Ehlers.


On page 9 of the paper (page 269 of the proceedings), there is a small error in the index bounds in the description of the safety automaton. The second and third bullet point in the definition of the transition function should read:


Relationship to other work

The paper discusses finding short accepting witnesses and lassos in omega-automata. As these can be seen as special cases of two-player games with omega-regular winning objectives, the results have some important implications for synthesis of finite-state systems: finding a system with as few states as possible satisfying the specification encoded into the game graph is a tough task: it is NP-hard to approximate within any polynomial.

The proof idea of Theorem 6 has been used independently in the paper “Equivalence and Inclusion Problem for Strongly Unambiguous Büchi Automata” by Nicolas Bousquet und Christof Löding, published also at LATA 2010.


The slides of the talk given at LATA 2010 are available here.