Minimization and Canonization of GFG Transition-Based Automata

While many applications of automata in formal methods can use nondeterministic automata, some applications, most notably synthesis, need deterministic or good-for-games (GFG) automata. The latter are nondeterministic automata that can resolve their nondeterministic choices in a way that only depends...

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Main Authors: Bader Abu Radi, Orna Kupferman
Format: Article
Language:English
Published: Logical Methods in Computer Science e.V. 2022-08-01
Series:Logical Methods in Computer Science
Subjects:
Online Access:https://lmcs.episciences.org/7587/pdf
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author Bader Abu Radi
Orna Kupferman
author_facet Bader Abu Radi
Orna Kupferman
author_sort Bader Abu Radi
collection DOAJ
description While many applications of automata in formal methods can use nondeterministic automata, some applications, most notably synthesis, need deterministic or good-for-games (GFG) automata. The latter are nondeterministic automata that can resolve their nondeterministic choices in a way that only depends on the past. The minimization problem for deterministic B\"uchi and co-B\"uchi word automata is NP-complete. In particular, no canonical minimal deterministic automaton exists, and a language may have different minimal deterministic automata. We describe a polynomial minimization algorithm for GFG co-B\"uchi word automata with transition-based acceptance. Thus, a run is accepting if it traverses a set $\alpha$ of designated transitions only finitely often. Our algorithm is based on a sequence of transformations we apply to the automaton, on top of which a minimal quotient automaton is defined. We use our minimization algorithm to show canonicity for transition-based GFG co-B\"uchi word automata: all minimal automata have isomorphic safe components (namely components obtained by restricting the transitions to these not in $\alpha$) and once we saturate the automata with $\alpha$-transitions, we get full isomorphism.
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spelling doaj.art-fc1e8b3f68ba4ae3a1b1f992edaea8722024-03-08T10:39:30ZengLogical Methods in Computer Science e.V.Logical Methods in Computer Science1860-59742022-08-01Volume 18, Issue 310.46298/lmcs-18(3:16)20227587Minimization and Canonization of GFG Transition-Based AutomataBader Abu RadiOrna KupfermanWhile many applications of automata in formal methods can use nondeterministic automata, some applications, most notably synthesis, need deterministic or good-for-games (GFG) automata. The latter are nondeterministic automata that can resolve their nondeterministic choices in a way that only depends on the past. The minimization problem for deterministic B\"uchi and co-B\"uchi word automata is NP-complete. In particular, no canonical minimal deterministic automaton exists, and a language may have different minimal deterministic automata. We describe a polynomial minimization algorithm for GFG co-B\"uchi word automata with transition-based acceptance. Thus, a run is accepting if it traverses a set $\alpha$ of designated transitions only finitely often. Our algorithm is based on a sequence of transformations we apply to the automaton, on top of which a minimal quotient automaton is defined. We use our minimization algorithm to show canonicity for transition-based GFG co-B\"uchi word automata: all minimal automata have isomorphic safe components (namely components obtained by restricting the transitions to these not in $\alpha$) and once we saturate the automata with $\alpha$-transitions, we get full isomorphism.https://lmcs.episciences.org/7587/pdfcomputer science - logic in computer sciencecomputer science - formal languages and automata theoryf.1.1f.4.3
spellingShingle Bader Abu Radi
Orna Kupferman
Minimization and Canonization of GFG Transition-Based Automata
Logical Methods in Computer Science
computer science - logic in computer science
computer science - formal languages and automata theory
f.1.1
f.4.3
title Minimization and Canonization of GFG Transition-Based Automata
title_full Minimization and Canonization of GFG Transition-Based Automata
title_fullStr Minimization and Canonization of GFG Transition-Based Automata
title_full_unstemmed Minimization and Canonization of GFG Transition-Based Automata
title_short Minimization and Canonization of GFG Transition-Based Automata
title_sort minimization and canonization of gfg transition based automata
topic computer science - logic in computer science
computer science - formal languages and automata theory
f.1.1
f.4.3
url https://lmcs.episciences.org/7587/pdf
work_keys_str_mv AT baderaburadi minimizationandcanonizationofgfgtransitionbasedautomata
AT ornakupferman minimizationandcanonizationofgfgtransitionbasedautomata