Mark Lawford

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In the first part of this paper, we generalize a notion of robust supervisory control to deal with marked languages. We show how to synthesize a supervisor to control a family of plant models, each with its own specification. The solution we obtain is the most general in that it provides the closest approximation to the supremal controllable sublanguage for(More)
DESPITE more than 30 years of effort to improve its quality, software is still released with many errors. Many major products are known to have thousands of bugs. It is not for lack of trying; all major software developers have a software quality assurance effort and attempt to remove bugs before release. The problem is the complexity of the code. It is(More)
In this paper, we present a hierarchical method that decomposes a system into two subsystems, and restricts the interaction of the subsystems by means of an interface. We present definitions for two types of interfaces [represented as discrete-event systems (DESs)], and define a set of interface consistency properties that can be used to verify if a DES is(More)
In this paper we present a hierarchical method that decomposes a system into two subsystems, and restricts the interaction of the subsystems by means of an interface. We present definitions for two types of interfaces (represented as discrete-event systems (DES)), and define a set of interface consistency properties that can be used to verify if a DES is(More)
In many Discrete Event Systems DES both state and event information are of im portance to the systems designer To obtain compositionally consistent hierarchical models of systems the behavior of Discrete Event Systems with unobservable tran sitions and state output maps is considered Observers for deterministic DES are generalized to nondeterministic DES(More)
In this paper we present a hierarchical method that decomposes a discrete-event system (DES) into a high level subsystem which communicates with parallel low level subsystems through separate interfaces, which restrict the interaction of the subsystems. We first review the setting for the serial case ( ) [1], and then generalize it for . We define an(More)
This paper considers supervisory control of probabilistic discrete event systems (PDES). PDESs are modeled as generators of probabilistic languages. The supervisory control problem considered is to find, if possible, a supervisor under whose control the behaviour of a plant is identical to a given probabilistic specification. The probabilistic supervisors(More)
Flexible manufacturing systems have long been touted as an application area for supervisory control theory. Unfortunately, due to the typical exponential growth of state space with the number of interacting subsystems, concurrent systems such as manufacturing applications have, for the most part, remained beyond the reach of existing supervisory control(More)