Semiring Provenance for Büchi Games: Strategy Analysis with Absorptive Polynomials

Erich Grädel
(RWTH Aachen University, Aachen, Germany)
Niels Lücking
(RWTH Aachen University, Aachen, Germany)
Matthias Naaf
(RWTH Aachen University, Aachen, Germany)

This paper presents a case study for the application of semiring semantics for fixed-point formulae to the analysis of strategies in Büchi games. Semiring semantics generalizes the classical Boolean semantics by permitting multiple truth values from certain semirings. Evaluating the fixed-point formula that defines the winning region in a given game in an appropriate semiring of polynomials provides not only the Boolean information on who wins, but also tells us how they win and which strategies they might use. This is well-understood for reachability games, where the winning region is definable as a least fixed point. The case of Büchi games is of special interest, not only due to their practical importance, but also because it is the simplest case where the fixed-point definition involves a genuine alternation of a greatest and a least fixed point.

We show that, in a precise sense, semiring semantics provide information about all absorption-dominant strategies - strategies that win with minimal effort, and we discuss how these relate to positional and the more general persistent strategies. This information enables applications such as game synthesis or determining minimal modifications to the game needed to change its outcome.

In Pierre Ganty and Davide Bresolin: Proceedings 12th International Symposium on Games, Automata, Logics, and Formal Verification (GandALF 2021), Padua, Italy, 20-22 September 2021, Electronic Proceedings in Theoretical Computer Science 346, pp. 67–82.
A full version of this paper, containing all proofs, appears at https://arxiv.org/abs/2106.12892
Published: 17th September 2021.

ArXived at: http://dx.doi.org/10.4204/EPTCS.346.5 bibtex PDF
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