Grente, Théo Grandjean, Etienne

The expressive power of the class Conj of conjunctive languages, i.e. languages generated by the conjunctive grammars of Okhotin, is largely unknown, while its restriction LinConj to linear conjunctive grammars equals the class of languages recognized by real-time one-way one-dimensional cellular automata. We prove two weakened versions of the open...

Bose, Sougata

The origin semantics for word transducers was introduced by Bojańczyk in 2014 in order to obtain a machine-independent characterization for word-to-word functions defined by transducers. Our primary goal was to study some classical decision problems for transducers in the origin semantics, such as the containment and the equivalence problem. We sho...

Bertrand, Nathalie Gramoli, Vincent Konnov, Igor Lazic, Marijana Tholoniat, Pierre Widder, Josef

Until now, computer-aided proofs of the liveness of byzantine consensus algorithms assumed synchrony to reason in lock steps or the error-prone manual intervention of experts in the proof checker, but could not be automated through model checking. We propose a compositional approach to verify a consensus algorithm, for any number n of processes and...

Chlyah, Sarah Gesbert, Nils Genevès, Pierre Layaïda, Nabil

We present an algebra with a fixpoint operator which is suitable for modeling computations with distributed collections found in big data frameworks. We show that under reasonable conditions this fixpoint can be evaluated by parallel loops with one final merge rather than by a global loop requiring network overhead after each iteration. We also sho...

Koutny, Maciej Kordon, Fabrice Pomello, Lucia

International audience

Grosshans, Nathan

The model of programs over (finite) monoids, introduced by Barrington and Thérien, gives an interesting way to characterise the circuit complexity class $\mathsf{NC^1}$ and its subclasses and showcases deep connections with algebraic automata theory. In this article, we investigate the computational power of programs over monoids in $\mathbf{J}$, a...

Boneva, Iovka Niehren, Joachim Sakho, Momar

We study the complexity of regular matching and inclusion for compressed tree patterns with context variables subject to regular constraints. Context variables with regular constraints permit to properly generalize on unranked tree patterns with hedge variables. Regular inclusion on unranked tree patterns is relevant to certain query answering on X...

Thierry-Mieg, Yann

Brute-force model-checking consists in exhaustive explorationof the state-space of a Petri net, and meets the dreaded state-space explosion problem.In contrast, this paper shows how to solve model-checking problems using a combination of techniques that stay in complexity proportional to the size of the net structure rather than to the state-space ...

Richomme, Gwenaël

The stable set associated to a given set S of nonerasing endomorphisms or substitutions is the set of all right infinite words that can be indefinitely desubstituted over S. This notion generalizes the notion of sets of fixed points of morphisms. It is linked to S-adicity and to property preserving morphisms. Two main questions are considered. Whic...

Salaün, Gwen

Equivalence checking is an established technique for automatically verifying that two behavioural models (Labelled Transition Systems, LTSs) are equivalent from the point of view of an external observer. When these models are not equivalent, the checker returns a Boolean result with a counterexample, which is a sequence of actions leading to a stat...