TY - GEN

T1 - Degrees of ambiguity for parity tree automata

AU - Rabinovich, Alexander

AU - Tiferet, Doron

N1 - Publisher Copyright:
© Alexander Rabinovich and Doron Tiferet.

PY - 2021/1

Y1 - 2021/1

N2 - An automaton is unambiguous if for every input it has at most one accepting computation. An automaton is finitely (respectively, countably) ambiguous if for every input it has at most finitely (respectively, countably) many accepting computations. An automaton is boundedly ambiguous if there is k ∈ N, such that for every input it has at most k accepting computations. We consider Parity Tree Automata (PTA) and prove that the problem whether a PTA is not unambiguous (respectively, is not boundedly ambiguous, not finitely ambiguous) is co-NP complete, and the problem whether a PTA is not countably ambiguous is co-NP hard.

AB - An automaton is unambiguous if for every input it has at most one accepting computation. An automaton is finitely (respectively, countably) ambiguous if for every input it has at most finitely (respectively, countably) many accepting computations. An automaton is boundedly ambiguous if there is k ∈ N, such that for every input it has at most k accepting computations. We consider Parity Tree Automata (PTA) and prove that the problem whether a PTA is not unambiguous (respectively, is not boundedly ambiguous, not finitely ambiguous) is co-NP complete, and the problem whether a PTA is not countably ambiguous is co-NP hard.

KW - Automata on infinite trees

KW - Degree of ambiguity

KW - Omega word automata

KW - Parity automata

UR - http://www.scopus.com/inward/record.url?scp=85100891096&partnerID=8YFLogxK

U2 - 10.4230/LIPIcs.CSL.2021.36

DO - 10.4230/LIPIcs.CSL.2021.36

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AN - SCOPUS:85100891096

T3 - Leibniz International Proceedings in Informatics, LIPIcs

BT - 29th EACSL Annual Conference on Computer Science Logic, CSL 2021

A2 - Baier, Christel

A2 - Goubault-Larrecq, Jean

PB - Schloss Dagstuhl- Leibniz-Zentrum fur Informatik GmbH, Dagstuhl Publishing

T2 - 29th EACSL Annual Conference on Computer Science Logic, CSL 2021

Y2 - 25 January 2021 through 28 January 2021

ER -