Max-plus algebra in the history of discrete event systems

This paper is a survey of the history of max-plus algebra and its role in the field of discrete event systems during the last three decades. It is based on the perspective of the authors but it covers a large variety of topics, where max-plus algebra plays a key role

Characterizations of recognizable picture series

AbstractThe theory of two-dimensional languages as a generalization of formal string languages was motivated by problems arising from image processing and pattern recognition, and also concerns models of parallel computing. Here we investigate power series on pictures. These are functions that map pictures to elements of a semiring and provide an extension of two-dimensional languages to a quantitative setting. We assign weights to different devices, ranging from picture automata to tiling systems. We will prove that, for commutative semirings, the behaviours of weighted picture automata are precisely alphabetic projections of series defined in terms of rational operations, and also coincide with the families of series characterized by weighted tiling or weighted domino systems

Aperiodic Weighted Automata and Weighted First-Order Logic

By fundamental results of Sch\"utzenberger, McNaughton and Papert from the 1970s, the classes of first-order definable and aperiodic languages coincide. Here, we extend this equivalence to a quantitative setting. For this, weighted automata form a general and widely studied model. We define a suitable notion of a weighted first-order logic. Then we show that this weighted first-order logic and aperiodic polynomially ambiguous weighted automata have the same expressive power. Moreover, we obtain such equivalence results for suitable weighted sublogics and finitely ambiguous or unambiguous aperiodic weighted automata. Our results hold for general weight structures, including all semirings, average computations of costs, bounded lattices, and others.Comment: An extended abstract of the paper appeared at MFCS'1

Residuation of tropical series: rationality issues

Decidability of existence, rationality of delay controllers and robust delay controllers are investigated for systems with time weights in the tropical and interval semirings. Depending on the (max,+) or (min,+)-rationality of the series specifying the controlled system and the control objective, cases are identified where the controller series defined by residuation is rational, and when it is positive (i.e., when delay control is feasible). When the control objective is specified by a tolerance, i.e. by two bounding rational series, a nice case is identified in which the controller series is of the same rational type as the system specification series.Les questions abordées dans ce rapport concernent l'existence et la rationalité d'un contrôleur (retardateur) pour des systèmes représentés par des automates à poids, dans des semi-anneaux tropicaux. Selon la (min,plus) ou (max,plus)-rationalité des séries spécifiant le système à contrôler et l'objectif du contrôle, on identifie des cas où le contrôleur défini par résiduation de séries est rationel et où il est positif (le système est alors contrôlable). Quand l'objectif de contrôle est spécifié par un intervalle de tolérance (encadrement par deux séries), un cas est identifié pour lequel la série du contrôleur a le même type de rationalité, (max,plus) ou (min,plus), que la spécification du système