9,365 research outputs found
Petri Games: Synthesis of Distributed Systems with Causal Memory
We present a new multiplayer game model for the interaction and the flow of
information in a distributed system. The players are tokens on a Petri net. As
long as the players move in independent parts of the net, they do not know of
each other; when they synchronize at a joint transition, each player gets
informed of the causal history of the other player. We show that for Petri
games with a single environment player and an arbitrary bounded number of
system players, deciding the existence of a safety strategy for the system
players is EXPTIME-complete.Comment: In Proceedings GandALF 2014, arXiv:1408.556
Characterizing Behavioural Congruences for Petri Nets
We exploit a notion of interface for Petri nets in order to design a set of net combinators. For such a calculus of nets, we focus on the behavioural congruences arising from four simple notions of behaviour, viz., traces, maximal traces, step, and maximal step traces, and from the corresponding four notions of bisimulation, viz., weak and weak step bisimulation and their maximal versions. We characterize such congruences via universal contexts and via games, providing in such a way an understanding of their discerning powers
Synthesis in Distributed Environments
Most approaches to the synthesis of reactive systems study the problem in terms of a two-player game with complete observation. In many applications, however, the system\u27s environment consists of several distinct entities, and the system must actively communicate with these entities in order to obtain information available in the environment. In this paper, we model such environments as a team of players and keep track of the information known to each individual player. This allows us to synthesize programs that interact with a distributed environment and leverage multiple interacting sources of information.
The synthesis problem in distributed environments corresponds to solving a special class of Petri games, i.e., multi-player games played over Petri nets, where the net has a distinguished token representing the system and an arbitrary number of tokens representing the environment. While, in general, even the decidability of Petri games is an open question, we show that the synthesis problem in distributed environments can be solved in polynomial time for nets with up to two environment tokens. For an arbitrary but fixed number of three or more environment tokens, the problem is NP-complete. If the number of environment tokens grows with the size of the net, the problem is EXPTIME-complete
Formal Approach Based on Petri Nets for Modeling and Verification of Video Games
Video games are complex systems that combine technical and artistic processes. The specification of this type of system is not a trivial task, making it necessary to use diagrams and charts to visually specify sets of requirements. Therefore, the underlying proposal of this work is to present an approach based on the formalism of Petri nets for aiding in the design process of video games. The activities of the game are represented by a specific type of Petri net called WorkFlow net. The definition of a topological map can be represented by state graphs. Using Colored Petri nets, it is possible to define formal communication mechanisms between the model of activity and the model of the map. The simulation of the timed models allows then to produce an estimated time that corresponds to the effective duration a player will need to complete a level of a game. Furthermore, a kind of Soundness property related to gameplay in a game Quest can be verified through state space analysis. For a better understanding of the approach, the video game Silent Hill II is used
Semantic analysis of field sports video using a petri-net of audio-visual concepts
The most common approach to automatic summarisation and highlight detection in sports video is to train an automatic classifier to detect semantic highlights based on occurrences of low-level features such as action replays, excited commentators or changes in a scoreboard. We propose an alternative approach based on the detection of perception concepts (PCs) and the construction of Petri-Nets which can be used for both semantic description and event detection within sports videos. Low-level algorithms for the detection of perception concepts using visual, aural and motion characteristics are proposed, and a series of Petri-Nets composed of perception concepts is formally defined to describe video content. We call this a Perception Concept Network-Petri Net (PCN-PN) model. Using PCN-PNs, personalized high-level semantic descriptions of video highlights can be facilitated and queries on high-level semantics can be achieved. A particular strength of this framework is that we can easily build semantic detectors based on PCN-PNs to search within sports videos and locate interesting events. Experimental results based on recorded sports
video data across three types of sports games (soccer, basketball and rugby), and each from multiple broadcasters, are used to illustrate the potential of this framework
Stubborn Set Reduction for Two-Player Reachability Games
Partial order reductions have been successfully applied to model checking of
concurrent systems and practical applications of the technique show nontrivial
reduction in the size of the explored state space. We present a theory of
partial order reduction based on stubborn sets in the game-theoretical setting
of 2-player games with reachability objectives. Our stubborn reduction allows
us to prune the interleaving behaviour of both players in the game, and we
formally prove its correctness on the class of games played on general labelled
transition systems. We then instantiate the framework to the class of weighted
Petri net games with inhibitor arcs and provide its efficient implementation in
the model checker TAPAAL. Finally, we evaluate our stubborn reduction on
several case studies and demonstrate its efficiency
Partial Order Reduction for Reachability Games
Partial order reductions have been successfully applied to model checking of concurrent systems and practical applications of the technique show nontrivial reduction in the size of the explored state space. We present a theory of partial order reduction based on stubborn sets in the game-theoretical setting of 2-player games with reachability/safety objectives. Our stubborn reduction allows us to prune the interleaving behaviour of both players in the game, and we formally prove its correctness on the class of games played on general labelled transition systems. We then instantiate the framework to the class of weighted Petri net games with inhibitor arcs and provide its efficient implementation in the model checker TAPAAL. Finally, we evaluate our stubborn reduction on several case studies and demonstrate its efficiency
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