TY - CONF
AB - Masaccio is a formal model for hybrid dynamical systems which are built from atomic discrete components (difference equations) and atomic continuous components (differential equations) by parallel and serial composition, arbitrarily nested. Each system component consists of an interface, which determines the possible ways of using the component, and a set of executions, which define the possible behaviors of the component in real time.
Version 1.0 (May 2000).
AU - Thomas Henzinger
ID - 4512
TI - Masaccio: A formal model for embedded components
VL - 1872
ER -
TY - CHAP
AU - Thomas Henzinger
ED - Inan, M. Kemal
ED - Kurshan, Robert P.
ID - 4513
T2 - Verification of Digital and Hybrid Systems
TI - The theory of hybrid automata
VL - 170
ER -
TY - JOUR
AB - 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 preserving all properties that are definable in temporal logic. The classes that permit discrete abstractions fall into two categories. Either the continuous dynamics must be restricted, as is the case for timed and rectangular hybrid systems, or the discrete dynamics must be restricted, as is the case for o-minimal hybrid systems. In this paper, we survey and unify results from both areas.
AU - Alur, Rajeev
AU - Thomas Henzinger
AU - Lafferriere, Gerardo
AU - Pappas, George J.
ID - 4598
IS - 7
JF - Proceedings of the IEEE
TI - Discrete abstractions of hybrid systems
VL - 88
ER -
TY - CONF
AB - We consider two-player games, which are played on a finite state space for an infinite number of rounds. The games are concurrent, that is, in each round, the two players choose their moves independently and simultaneously; the current state and the two moves determine a successor state. We consider omega-regular winning conditions on the resulting infinite state sequence. To model the independent choice of moves, both players are allowed to use randomization for selecting their moves. This gives rise to the following qualitative modes of winning, which can be studied without numerical considerations concerning probabilities: sure-win (player 1 can ensure winning with certainty), almost-sure-win (player 1 can ensure winning with probability 1), limit-win (player 1 can ensure winning with probability arbitrarily close to 1), bounded-win (player 1 can ensure winning with probability bounded away from 0), positive-win (player 1 can ensure winning with positive probability), and exist-win (player 1 can ensure that at least one possible outcome of the game satisfies the winning condition).We provide algorithms for computing the sets of winning states for each of these winning modes. In particular, we solve concurrent Rabin-chain games in n0 (m) time, where n is the size of the game structure and m is the number of pairs in the Rabin-chain condition. While this complexity is in line with traditional turn-based games, where in each state only one of the two players has a choice of moves, our algorithms are considerably more involved than those for turn-based games are. This is because concurrent games violate two of the most fundamental properties of turn-based games. First, concurrent games are not determined, but rather exhibit a more general duality property, which involves multiple modes of winning. Second, winning strategies for concurrent games may require infinite memory.
AU - de Alfaro, Luca
AU - Thomas Henzinger
ID - 4627
TI - Concurrent omega-regular games
ER -
TY - CONF
AB - In the synchronous composition of processes, one process may prevent another process from proceeding unless compositions without a well-defined product behavior are ruled out. They can be ruled out semantically, by insisting on the existence of certain fixed points, or syntactically, by equipping processes with types, which make the dependencies between input and output signals transparent. We classify various typing mechanisms and study their effects on the control problem.
A static type enforces fixed, acyclic dependencies between input and output ports. For example, synchronous hardware without combinational loops can be typed statically. A dynamic type may vary the dependencies from state to state, while maintaining acyclicity, as in level-sensitive latches. Then, two dynamically typed processes can be syntactically compatible, if all pairs of possible dependencies are compatible, or semantically compatible, if in each state the combined dependencies remain acyclic. For a given plant process and control objective, there may be a controller of a static type, or only a controller of a syntactically compatible dynamic type, or only a controller of a semantically compatible dynamic type. We show this to be a strict hierarchy of possibilities, and we present algorithms and determine the complexity of the corresponding control problems.
Furthermore, we consider versions of the control problem in which the type of the controller (static or dynamic) is given. We show that the solution of these fixed-type control problems requires the evaluation of partially ordered (Henkin) quantifiers on boolean formulas, and is therefore harder (nondeterministic exponential time) than more traditional control questions
AU - de Alfaro, Luca
AU - Thomas Henzinger
AU - Mang, Freddy Y
ID - 4637
TI - The control of synchronous systems
VL - 1877
ER -