This paper treats deadlocks and liveness of the closed-loop discrete event system GSCSM|f consisting of a strongly connected state machine (SCSM), a subclass of Petri nets, and a state-feedback which realizes the mutually exclusive control. The GSCSM|f is not always live even if the original SCSM is live, and deadlocks exist in GSCSM|f. A deadlock marking is newly defined and the D-net is propo...

Approaches for Deadlock Detection and Prevention in Distributed Database System Swati Gupta Lecturer, Department of Computer Science Amity University Haryana ,Gurgaon, India _______________________________________________________________________________________ Abstract: A distributed database system consists of different number of sites that are inter connected by a communication network. A de...

This paper focuses on the problem of deadlocks in automated flexible manufacturing systems (FMS) where deadlocks are caused by unmarked siphons in their Petri net models. A deadlock prevention policy is proposed for a subclass of Petri nets, SPMR that can well model a large class of FMS. We distinguish siphons in such a net model by elementary and dependent ones. For each elementary siphon, a m...

Open distributed systems are essential in today’s software solutions. However, not all programming paradigms provide natural support for such systems. The setting of concurrent objects is attractive since it supports independent units of computation. In particular we consider concurrent objects communicating by asynchronous method calls supporting nonblocking as well as blocking method calls. I...

Despite the advancements of concurrency theory in the past decades, practical concurrent programming has remained a challenging activity. Fundamental problems such as data races and deadlocks still persist for programmers since available detection and prevention tools are unsound or have otherwise not been well adopted. In an alternative approach, programming models that exclude certain classes...

We give two different notions of deadlock for systems based on active objects and futures. One is based on blocked objects and conforms with the classical definition of deadlock by Coffman, Jr. et al. The other one is an extended notion of deadlock based on blocked processes which is more general than the classical one. We introduce a technique to prove deadlock freedom of systems of active obj...

This paper focuses on timed models which represent closed-loop systems composed of a plant and a logic controller. Both plant and controller models are described in a formalism where urgent transitions are possible, to avoid non-realistic evolutions, and without deadlock when they are separated. It is first shown that deadlocks may occur in the plant model once the two models are coupled. To so...

In this paper, we propose a decentralized coordina- tion algorithm for safe and efficient management of a group of mobile robots following predefined paths in a dynamic industrial environment. The proposed algorithm is based on a shared resources protocol and a replanning strategy. It is proved to guarantee ordered traffic flows avoiding collisions, deadlocks (stall situations) and livelock (ag...

Distributed database system provides resource sharing environment for optimal performance of various database activities, especially when data is spread over a large number of sites. Distributed nature of transactions occurring at different sites and requiring resources from diverse sites pose various operational problems, such as deadlocks, concurrency and data recovery. A deadlock may occur w...

This paper focuses on the problem of deadlocks in automated flexible manufacturing systems (FMS) where deadlocks are caused by unmarked siphons in their Petri net models. A deadlock prevention policy is proposed for a subclass of Petri nets, SPMR that can well model a large class of FMS. We distinguish siphons in such a net model by elementary and dependent ones. For each elementary siphon, a m...