Interactive Scores (IS) are a formalism for the design and performance of interactive multimedia scenarios. IS provide temporal relations (TR), but they cannot represent conditional branching and TRs simultaneously. We propose an extension to 's IS model by including a condition on the TRs. We found out that in order to have a coherent model in all possible scenarios, durations must be flexible; however, sometimes it is possible to have fixed durations. To show the relevance of our model, we modeled an existing multimedia installation called Mariona. In Mariona there is choice, random durations and loops. Whether we can represent all the TRs available in 's model into ours, or we have to choose between a timed conditional branching model and a pure temporal model before writing a scenario, still remains as an open question.
An advantage of using formal methods to model interactive multimedia is that they usually have automatic verification techniques. There are numerous studies to verify liveness, fairness, reachability and boundness on Petri Networks @cite_3 . On the other hand, in the last years, calculi similar to ntcc have been subject of study for automatic model checking procedures @cite_18 .
@cite_18 @cite_3
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The language Timed Concurrent Constraint (tccp) is the extension over time of the Concurrent Constraint Programming (cc) paradigm that allows us to specify concurrent systems where timing is critical, for example reactive systems . Systems which may have an infinite number of states can be specified in tccp. Model checking is a technique which is able to verify finite-state systems with a huge number of states in an automatic way. In the last years several studies have investigated how to extend model checking techniques to systems with an infinite number of states. In this paper we propose an approach which exploits the computation model of tccp. Constraint based computations allow us to define a methodology for applying a model checking algorithm to (a class of) infinite-state systems. We extend the classical algorithm of model checking for LTL to a specific logic defined for the verification of tccp and to the tccp Structure which we define in this work for modeling the program behavior. We define a restriction on the time in order to get a finite model and then we develop some illustrative examples. To the best of our knowledge this is the first approach that defines a model checking methodology for tccp. Starts with a brief review of the history and the application areas considered in the literature. The author then proceeds with introductory modeling examples, behavioral and structural properties, three methods of analysis, subclasses of Petri nets and their analysis. In particular, one section is devoted to marked graphs, the concurrent system model most amenable to analysis. Introductory discussions on stochastic nets with their application to performance modeling, and on high-level nets with their application to logic programming, are provided. Also included are recent results on reachability criteria. Suggestions are provided for further reading on many subject areas of Petri nets. >