Compositions of (max,+) automata

Automata with weights (multiplicities) in the so called (max,+) semiring constitute a class of timed automata. Their modeling power has been studied in Gaubert and Mairesse (1999): at least timed safe Petri nets can be modeled by means of (max,+) automata.In this contribution, we define compositions for (max,+) automata. The motivation is to be able to model a complex system by composing sub-models representing its elementary parts. In doing so we expect two benefits: the modeling activity should be eased and enhanced since the model can be obtained in a modular manner with a good understanding of phenomena; the modeling power of (max,+) automata can be refined.