314 research outputs found
Random Fruits on the Zielonka Tree
Stochastic games are a natural model for the synthesis of controllers
confronted to adversarial and/or random actions. In particular,
-regular games of infinite length can represent reactive systems which
are not expected to reach a correct state, but rather to handle a continuous
stream of events. One critical resource in such applications is the memory used
by the controller. In this paper, we study the amount of memory that can be
saved through the use of randomisation in strategies, and present matching
upper and lower bounds for stochastic Muller games
Optimal Strategy Synthesis for Request-Response Games
We show the existence and effective computability of optimal winning
strategies for request-response games in case the quality of a play is measured
by the limit superior of the mean accumulated waiting times between requests
and their responses.Comment: The present paper is a revised version with simplified proofs of
results announced in the conference paper of the same name presented at ATVA
2008, which in turn extended results of the third author's dissertatio
Solving the TTC 2011 Reengineering Case with GReTL
This paper discusses the GReTL reference solution of the TTC 2011
Reengineering case. Given a Java syntax graph, a simple state machine model has
to be extracted. The submitted solution covers both the core task and the two
extension tasks.Comment: In Proceedings TTC 2011, arXiv:1111.440
Random Fruits on the Zielonka Tree
Stochastic games are a natural model for the synthesis of controllers confronted to adversarial and/or random actions. In particular, -regular games of infinite length can represent reactive systems which are not expected to reach a correct state, but rather to handle a continuous stream of events. One critical resource in such applications is the memory used by the controller. In this paper, we study the amount of memory that can be saved through the use of randomisation in strategies, and present matching upper and lower bounds for stochastic Muller games
Solving Simple Stochastic Games with Few Random Vertices
Simple stochastic games are two-player zero-sum stochastic games with turn-based moves, perfect information, and reachability winning conditions. We present two new algorithms computing the values of simple stochastic games. Both of them rely on the existence of optimal permutation strategies, a class of positional strategies derived from permutations of the random vertices. The "permutation-enumeration" algorithm performs an exhaustive search among these strategies, while the "permutation-improvement'' algorithm is based on successive improvements, Ã la Hoffman-Karp. Our algorithms improve previously known algorithms in several aspects. First they run in polynomial time when the number of random vertices is fixed, so the problem of solving simple stochastic games is fixed-parameter tractable when the parameter is the number of random vertices. Furthermore, our algorithms do not require the input game to be transformed into a stopping game. Finally, the permutation-enumeration algorithm does not use linear programming, while the permutation-improvement algorithm may run in polynomial time
Self-stabilizing K-out-of-L exclusion on tree network
In this paper, we address the problem of K-out-of-L exclusion, a
generalization of the mutual exclusion problem, in which there are units
of a shared resource, and any process can request up to units
(). We propose the first deterministic self-stabilizing
distributed K-out-of-L exclusion protocol in message-passing systems for
asynchronous oriented tree networks which assumes bounded local memory for each
process.Comment: 15 page
The surprizing complexity of generalized reachability games
Games on graphs provide a natural and powerful model for reactive systems. In this paper, we consider generalized reachability objectives, defined as conjunctions of reachability objectives. We first prove that deciding the winner in such games is \PSPACE-complete, although it is fixed-parameter tractable with the number of reachability objectives as parameter. Moreover, we consider the memory requirements for both players and give matching upper and lower bounds on the size of winning strategies. In order to allow more efficient algorithms, we consider subclasses of generalized reachability games. We show that bounding the size of the reachability sets gives two natural subclasses where deciding the winner can be done efficiently
Deciding the Existence of Cut-Off in Parameterized Rendez-Vous Networks
We study networks of processes which all execute the same finite-state protocol and communicate thanks to a rendez-vous mechanism. Given a protocol, we are interested in checking whether there exists a number, called a cut-off, such that in any networks with a bigger number of participants, there is an execution where all the entities end in some final states. We provide decidability and complexity results of this problem under various assumptions, such as absence/presence of a leader or symmetric/asymmetric rendez-vous
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