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We propose timed (j&e) automata to model the behavior of real-time systems over time. Our definition provides a simple, and yet powerful, way to annotate state-transition graphs with timing constraints using finitely many real-valued clocks. A timed automaton accepts timed words-infinite sequences in which a real-valued time of occurrence is associated with(More)
We present a general framework for the formal speciication and algorithmic analysis of hybrid systems. A hybrid system consists of a discrete program with an analog environment. We model hybrid systems as nite automata equipped with variables that evolve continuously with time according to dynamical laws. For veriication purposes, we restrict ourselves to(More)
We propose the class of <i>visibly pushdown languages</i> as embeddings of context-free languages that is rich enough to model program analysis questions and yet is tractable and robust like the class of regular languages. In our definition, the input symbol determines when the pushdown automaton can push or pop, and thus the stack depth at every position.(More)
A hybrid system is a dynamical system with both discrete and continuous state changes. For analysis purposes, it is often useful to abstract a system in a way that preserves the properties being analyzed while hiding the details that are of no interest. We show that interesting classes of hybrid systems can be abstracted to purely discrete systems while(More)
We i n troduce the framework of hybrid automata as a model and speciication language for hybrid systems. Hybrid automata can be viewed as a generalization of timed automata, in which the behavior of variables is governed in each state by a set of diierential equations. We s h o w that many of the examples considered in the workshop can be deened by h ybrid(More)
The theory of the natural numbers with linear order and monadic predicates underlies propositional linear temporal logic. To study temporal logics that are suitable for reasoning about real-time systems, we combine this classical theory of innnite state sequences with a theory of discrete time, via a monotonic function that maps every state to its time. The(More)
We describe a new interactive veriication environment called Mocha for modular veriication of heterogeneous systems. Mocha diiers from existing model checkers in three important ways. First, instead of manipulating unstructured state-transition graphs, it supports the heterogeneous modeling framework of Reactive Modules. Second, instead of traditional(More)