In this paper, we first study the conversion of weighted two-way automata to one-way automata. We show that this conversion preserves the unambiguity but does not preserve the determinism. Yet, we prove that the conversion of an unambiguous weighted one-way automaton into a two-way automaton leads to a deterministic two-way automaton. As a consequence, we prove that unambiguous weighted two-way automata are equivalent to deterministic weighted two-way automata in commutative semirings.Comment: In Proceedings AFL 2014, arXiv:1405.527

Abstract. In this article we propose an algorithm, based on Markov chain techniques, to generate random automata that are deterministic, accessible and acyclic. The distribution of the output approaches the uniform distribution on n-state such automata. We then show how to adapt this algorithm in order to generate minimal acyclic automata with n states almost uniformly.

International audienceWe propose algorithms that use Markov chain techniques to generate acyclic automata uniformly at random. We first consider deterministic, accessible and acyclic automata, then focus on the class of minimal acyclic automata. In each case we explain how to define random local transformations that describe an ergodic and symmetric Markov chain; the distribution of the automaton obtained after T random steps in this Markov chain tends to the uniform distribution as T tends to infinity

Part 2: Track B: Logic, Semantics, Specification and VerificationInternational audienceIn this paper we study two-way min-plus automata. We prove that two-way distance automata are equivalent to one-way distance automata. In the second part of the paper we show that, with general min-plus semirings, it is decidable whether every accepted word has a finite weight and that, in contrast, it is undecidable whether there exists a word accepted with a finite weight

Abstract. In this paper, we extend the concept of factorization on finite words to ω-rational languages and show how to compute them. We define a normal form for Büchi automata and introduce a universal automaton for Büchi automata in normal form. We prove that, for every ω-rational language, this Büchi automaton, based on factorization, is canonical and that it is the smallest automaton that contains the morphic image of every equivalent Büchi automaton in normal form.