Thibaud Michaud

The reactive synthesis competition (SYNTCOMP): 2018-2021

Abstract

We report on the last four editions of the reactive synthesis competition (SYNTCOMP 2018–2021). We briefly describe the evaluation scheme and the experimental setup of SYNTCOMP. Then we introduce new benchmark classes that have been added to the SYNTCOMP library and give an overview of the participants of SYNTCOMP. Finally, we present and analyze the results of our experimental evaluations, including a ranking of tools with respect to quantity and quality—that is, the total size in terms of logic and memory elements—of solutions.

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The reactive synthesis competition (SYNTCOMP): 2018-2021

Abstract

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Reactive synthesis from LTL specification with Spot

Abstract

We present ltlsynt, a new tool for reactive synthesis from LTL specifications. It relies on the efficiency of Spot to translate the input LTL specification to a deterministic parity automaton. The latter yields a parity game, which we solve with Zielonka’s recursive algorithm.The approach taken in ltlsynt was widely believed to be impractical, due to the double-exponential size of the parity game, and to the open status of the complexity of parity games resolution. ltlsynt ranked second of its track in the $2017$ edition of the SYNTCOMP competition. This demonstrates the practical applicability of the parity game approach, when backed by efficient manipulations of $\omega$-automata such as the ones provided by Spot. We present our approach and report on our experimental evaluation of ltlsynt to better understand its strengths and weaknesses.

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Derived-term automata of weighted rational expressions with quotient operators

Abstract

Quotient operators have been rarely studied in the context of weighted rational expressions and automaton generation—in spite of the key role played by the quotient of words in formal language theory. To handle both left- and right-quotients we generalize an expansion-based construction of the derived-term (or Antimirov, or equation) automaton and rely on support for a transposition (or reversal) operator. The resulting automata may have spontaneous transitions, which requires different techniques from the usual derived-term constructions.

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The 4th reactive synthesis competition (SYNTCOMP 2017): Benchmarks, participants & results

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Spot 2.0 — a framework for LTL and $\omega$-automata manipulation

Abstract

We present Spot 2.0, a C++ library with Python bindings and an assortment of command-line tools designed to manipulate LTL and $\omega$-automata in batch. New automata-manipulation tools were introduced in Spot 2.0; they support arbitrary acceptance conditions, as expressible in the Hanoi Omega Automaton format. Besides being useful to researchers who have automata to process, its Python bindings can also be used in interactive environments to teach $\omega$-automata and model checking.

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Practical stutter-invariance checks for $\omega$-regular languages

Abstract

We propose several automata-based constructions that check whether a specification is stutter-invariant. These constructions assume that a specification and its negation can be translated into Büchi automata, but aside from that, they are independent of the specification formalism. These transformations were inspired by a construction due to Holzmann and Kupferman, but that we broke down into two operations that can have different realizations, and that can be combined in different ways. As it turns out, implementing only one of these operations is needed to obtain a functional stutter-invariant check. Finally we have implemented these techniques in a tool so that users can easily check whether an LTL or PSL formula is stutter-invariant.

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