Quentin Menet

Almost-Sure Model-Checking of Reactive Timed Automata

We consider the model of stochastic timed automata, a model in which both delays and discrete choices are made probabilistically. We are interested in the almost-sure model-checking problem, which asks whether the automaton satisfies a given property with probability 1. While this problem was shown decidable for single-clock automata few years ago, it was also proven that the algorithm for this decidability result could not be used for general timed automata. In this paper we describe the subclass of reactive timed automata, and we prove decidability of the almost-sure model-checking problem under that restriction. Decidability relies on the fact that this model is almost-surely fair. As a desirable property of real systems, we show that reactive automata are almost-surely non-Zeno. Finally we show that the almost-sure model-checking problem can be decided for specifications given as deterministic timed automata.

Stochastic Timed Automata

A stochastic timed automaton is a purely stochastic process defined on a timed automaton, in which both delays and discrete choices are made randomly. We study the almost-sure model-checking problem for this model, that is, given a stochastic timed automaton A and a property

Hypercyclic Subspaces on Fréchet Spaces Without Continuous Norm

\Phi

Existence and non-existence of frequently hypercyclic subspaces for weighted shifts

, we want to decide whether A satisfies

Compositional Design of Stochastic Timed Automata

\Phi

Simple strategies for Banach-Mazur games and sets of probability 1

with probability 1. In this paper, we identify several classes of automata and of properties for which this can be decided. The proof relies on the construction of a finite abstraction, called the thick graph, that we interpret as a finite Markov chain, and for which we can decide the almost-sure model-checking problem. Correctness of the abstraction holds when automata are almost-surely fair, which we show, is the case for two large classes of systems, single- clock automata and so-called weak-reactive automata. Techniques employed in this article gather tools from real-time verification and probabilistic verification, as well as topological games played on timed automata.

Recurrence properties of hypercyclic operators

Known results about hypercyclic subspaces concern either Fréchet spaces with a continuous norm or the space ω. We fill the gap between these spaces by investigating Fréchet spaces without continuous norm. To this end, we divide hypercyclic subspaces into two types: the hypercyclic subspaces M for which there exists a continuous seminorm p such that

Linear chaos and frequent hypercyclicity

{M \cap {\rm ker} p = \{0\}}