A Uniform Treatment of Architectures in Decentralized Discrete-Event System

Solutions to decentralized discrete-event systems problems are characterized by the way local decisions are fused to yield a global decision. A fusion rule is colloquially called an architecture. This paper provides a uniform treatment of architectures in decentralized discrete-event systems. Current approaches neither provide a direct way to determine problem solvability conditions under one architecture, nor a way to compare existing architectures. Determining whether a new architecture is more general than an existing known architecture relies on producing examples ad hoc and on individual inspiration that puts the conditions for solvability in each architecture into some form that admits comparison. From these research efforts, a method based on morphisms between graphs has been extracted to yield a uniform approach to decentralized discrete-event system architectures and their attendant fusion rules. This treatment provides an easy and direct way to compare the fusion rules -- and hence to compare the strength or generality of the corresponding architectures

Combining Model Checking and Discrete-Event Supervisor Synthesis

We present an approach to facilitate the design of provably correct concurrent systems by recasting recent work that uses discrete-event supervisor synthesis to automatically generate concurrency control code in Promela and combine it with model checking in Spin. This approach consists of the possibly repeated execution of three steps: manual preparation, automatic synthesis, and semi-automatic analysis. Given a concurrent Promela program C devoid of any concurrency control and an informal specification E_in , the preparation step is assumed to yield a formal specification E of the allowed system behaviours and two versions of C: C_e to identify the specification-relevant events in C and enable supervisor synthesis, and C_e,a to introduce “checkable redundancy” and used during the analysis step to locate bugs in: the specification formalization E, the event markup in C_e, or the implementation of the synthesis. The result is supervised Promela code C_sup that is more likely to be correct with respect to E and E_in. The approach is illustrated with an example. A prototype tool implementing the approach is described

Template design and automatic generation of controllers for industrial robots

The basic theory of supervisory control of discrete-event sys-tems is extended with the notion of templates, which sim-plifies the modeling of controllers since one can work with conceptual designs. In this work, software which provides support for the new design approach is presented along with its application to a robotic testbed

A correspondence between control and observation problems in decentralized discrete-event systems

This paper demonstrates a correspondence between control problems (with partial observation) and observation problems in decentralized discrete-event systems, namely, the two classes of problems are Turing equivalent, as one class Turing reduces to the other. The correspondence allows decomposition of a control problem into a collection of simpler control sub-problems. Since observation problems in their most general formulation have been shown to be undecidable in previous work, the correspondence produced in this paper demonstrates that control problems -- in their most general form -- is also undecidable

The computational complexity of decentralized discrete-event control problems

Computational complexity results are obtained for decentralized discrete-event system problems. These results generalize the earlier work of Tsitsiklis, who showed that for centralized supervisory control problems (under partial observation), solution existence is decidable in polynomial time for a special type of problem but becomes computationally intractable for the general class. As in the case of centralized control, there is no polynomial-time algorithm for producing supervisor solutions

The computational complexity of decentralized discrete-event control problems

Supervisory control themy is the study of discrete-event processes, such as computer systems and manufacturing systems, which require control to induce desirable behavior. Informally, a dimte-event system is a process (or set of processes) that suns out in som

Protocol Verification Using Discrete-Event Systems

It can be shown that the problem of reliable transmission of data over an unreliable communication channel can be restated as a decentralized control problem of discrete-event systems. Necessary and sufficient conditions for the existence of solutions to such decentralized supervisory control problems have been found. These conditions are used to verify the correctness of a protocol for the data transmission problem. In particular, it is demonstrated that our method provides a systematic check on whether the protocol satisfies the required safety property, asopposed to relying on finding, ad hoc, circumstances under which the protocol fails