Predicate Transition Nets Research Articles

A methodology for constructing predicate transition net specifications

AbstractIn this paper, a methodology for constructing hierarchical and structured predicate transition net specifications is developed, which includes new systematic notation extensions for supporting various transformation techniques upon predicate transition nets and several rules for applying such transformation techniques. The levelling technique in data‐flow diagrams is adapted in the refinement and the abstraction techniques, and the state decomposition idea in state‐charts is employed in designing various label formulation operators. The methodology is illustrated through the specification of a lift system. The methodology can significantly reduce the constructing complexity and enhance the comprehensibility of large predicate transition net specifications.

Integrating predicate transition nets with first order temporal logic in the specification and verification of concurrent systems

Abstract This paper presents some results of integrating predicate transition nets with first order temporal logic in the specification and verification of concurrent systems. The intention of this research is to use predicate transition nets as a specification method and to use first order temporal logic as a verification method so that their strengths — the easy comprehension of predicate transition nets and the reasoning power of first order temporal logic can be combined. In this paper, a theoretical relationship between the computation models of these two formalisms is presented; an algorithm for systematically translating a predicate transition net into a corresponding temporal logic system is outlined; and a special temporal refutation proof technique is proposed and illustrated in verifying various concurrent properties of the predicate transition net specification of the five dining philosophers problem.

Analysis and Evaluation of Decision Aids in Organizations

A methodology for the modeling and evaluation of decision aids is presented. Petri Net models of human decisionmakers and decision aids are described that can be interconnected to represent organizations. The approach is illustrated by modeling and analyzing the effects of a class of decision aids that is based on artificial intelligence and especially expert systems. This paper presents a procedure for assessing to what extent the measures of performance of an organization are modified when an expert system is introduced. First, a model of symbolic computation with fuzzy logic, using Predicate Transition Nets, is presented to model the most common kind of expert systems: the consultant expert systems. This model allows to evaluate its response time for a given input. An example problem involving a hierarchical two decisionmaker organization, where the expert system is used as an aid in the fusion of inconsistent information, is then presented. A strategy involving the use of the expert system is compared to two other strategies expected to be used by a decisionmaker responsible for this task. Measures of performance (workload, timeliness and accuracy) are evaluated for each of these strategies. The results show that the strategy involving the use of the expert system improves significantly the accuracy of the organization, but requires more time and increases the workload of the decisionmaker using it.

A model for the protocol design of back-end storage networks

This work presents a formal design for the system protocols of back-end storage networks. Such design relies on predicate-transition nets (PrT-nets). These nets actually represent an extension of Petri nets and can provide reasonable means for precise modeling of complex systems. The given model has demonstrated that by using PrT-nets the protocols of back-end networks can be constructed and interpreted in a natural manner. In that model we employed mainly two types of tokens, one to simulate user programs and requests and the other to express synchronization and control. To build up the model we used a modular approach. Each module is represented by a phase in the protocol net so that the complete design can eventually realize the required system specifications. Also, an insight into the design is emphasized and the validation of the protocol is pointed out. Accordingly, a well-behaved system is obtained so that the shared data is free from inconsistency, deadlocks, and residual signals.