Showing papers on "Petri net published in 1988"
01 Jun 1988
TL;DR: In this paper, the authors summarize the lines of research that are currently being pursued, and explain what new results would be regarded as breakthroughs and have the most impact on the use of this modeling technique in the application field.
Abstract: Petri nets in which random firing delays are associated with transitions whose firing is an atomic operation are known under the name “stochastic Petri nets” These models are discussed, with the purpose of explaining why they were proposed in the performance evaluation field, why random delays with negative exponential probability density functions are mainly used, and what are their strong and weak points An effort is made to summarize the lines of research that are currently being pursued, and to explain what new results would be regarded as breakthroughs and have the most impact on the use of this modeling technique in the application field
319 citations
01 Jun 1988
TL;DR: The aim of this invited survey is to introduce Computer science/Petri nets specialists to the basic system level issues brought up by the development of Flexible Manufacturing and how Petri nets are used to aid the production engineers in their work.
Abstract: The aim of this invited survey is to introduce Computer science/Petri nets specialists to the basic system level issues brought up by the development of Flexible Manufacturing and how Petri nets are used to aid the production engineers in their work. After some terminology concerning production engineering, the hierarchical decision and control level is briefly reviewed. Finally, the role and the presence of nets in CAE (Computer Aided Engineering) and in CAM (Computer Aided Manufacturing) for FMSs (Flexible Manufacturing Systems) are considered. From the design point of view, the use of nets have many advantages in modeling, qualitative analysis, performance evaluation and code generation. From the control of the plant perspective, scheduling on nets models, the coordination of the plant (global and partial) and the presence of nets in the local control level are discussed.
246 citations
30 May 1988
TL;DR: These notes are intended to introduce the mathematical theory of event structures, show how they are related to Petri nets and Scott domains, and how they can be used to provide semantics to programming languages for parallel processes as well as languages with higher types.
Abstract: Event structures are models of processes as events constrained by relations of consistency and enabling. These notes are intended to introduce the mathematical theory of event structures, show how they are related to Petri nets and Scott domains, and how they can be used to provide semantics to programming languages for parallel processes as well as languages with higher types.
216 citations
30 May 1988
TL;DR: The theory of traces can be used as a tool for reasoning about nets and it is hoped that applying this theory one can get a calculus of the concurrent processes analogous to that available for sequential systems.
Abstract: The concept of traces has been introduced for describing non-sequential behaviour of concurrent systems via its sequential observations. Traces represent concurrent processes in the same way as strings represent sequential ones. The theory of traces can be used as a tool for reasoning about nets and it is hoped that applying this theory one can get a calculus of the concurrent processes analogous to that available for sequential systems. The following topics will be discussed: algebraic properties of traces, trace models of some concurrency phenomena, fixed-point calculus for finding the behaviour of nets, modularity, and some applications of the presented theory.
216 citations
TL;DR: Modeling elements that have gained widespread use for general systems, as well as fault-tolerant systems, are included and can be used to aid in selecting models and tools for a particular application or designing tools for future needs.
Abstract: In computer design, it is essential to know the effectiveness of different design options in improving performance and dependability. Various software tools have been created to evaluate these parameters, applying both analytic and simulation techniques, and this paper reviews those related primarily to reliability, availability, and serviceability. The purpose, type of models used, type of systems modeled, inputs, and outputs are given for each package. Examples of some of the key modeling elements such as Markov chains, fault trees, and Petri nets are discussed. The information is compiled to facilitate recognition of similarities and differences between various models and tools and can be used to aid in selecting models and tools for a particular application or designing tools for future needs. Tools included in the evaluation are CARE-III, ARIES-82, SAVE, MARKl, HARP, SHARPE, GRAMP, SURF, SURE, ASSIST, METASAN, METFAC, ARM, and SUPER. Modeling tools, such as REL70, RELCOMP, CARE, CARSRA, and CAST, that were forerunners to some of the current tools are noted for their contributions. Modeling elements that have gained widespread use for general systems, as well as fault-tolerant systems, are included. Tools capable of modeling both repairable and nonrepairable systems, accepting constant or time varying failure rates, and predicting reliability, availability, and serviceability parameters are surveyed.
189 citations
TL;DR: The PROTEAN protocol emulation and analysis computer aid is presented, and it is based on a formal specification technique called numerical Petri nets, and provides both graphical (color) and textual interfaces to the protocol designer.
Abstract: The PROTEAN protocol emulation and analysis computer aid is presented. It is based on a formal specification technique called numerical Petri nets (NPNs), and provides both graphical (color) and textual interfaces to the protocol designer. NPN specifications may be created, stored, appended to other NPNs, structured, edited, listed, displayed, and analyzed. Interactive simulation, exhaustive reachability analysis, and several directed graph analysis facilities are described. Specification languages are compared, with concentration on extended finite state machines and high-level Petri nets. Both the NPN and PROTEAN facilities are described and illustrated with a simple example. The application of PROTEAN to complex examples is mentioned briefly. Work towards a comprehensive protocol engineering workstation is also discussed. >
165 citations
TL;DR: A new set of inference rules for the guarded version of Milner's Calculus of Communicating Systems is proposed that not only describe the actions agents may perform when in a given state, but also say which parts of the agents move when the global state changes.
Abstract: A new set of inference rules for the guarded version of Milner’s Calculus of Communicating Systems is proposed. They not only describe the actions agents may perform when in a given state, but also say which parts of the agents move when the global state changes. From the transition relation a particular Petri Net, namely a Condition/Event system called ΣCCS, is immediately derived. Our construction gives a semantics which is consistent with the interleaving semantics of CCS and exhibits full parallelism. The proof consists of relating the case graph of ΣCCS with the original and with the multiset (step) transition systems of the calculus.
154 citations
TL;DR: Petri nets are used as a design representation of an FMS for the purpose of comparing different systems on a flexibility basis thus unveiling their desirable flexibility properties.
Abstract: A discussion on the multi-dimensional character of flexibility is presented and an approach is suggested to define and measure flexibility. Petri nets are used as a design representation of an FMS for the purpose of comparing different systems on a flexibility basis thus unveiling their desirable flexibility properties.
151 citations
01 Jan 1988
130 citations
TL;DR: A technique is presented whereby queueing network models and generalized stochastic Petri nets are combined in such a way as to exploit the best features of both modeling techniques, and the resulting hierarchical modeling approach is useful in the solution of complex models of system behavior.
Abstract: A technique is presented whereby queueing network models and generalized stochastic Petri nets are combined in such a way as to exploit the best features of both modeling techniques. The resulting hierarchical modeling approach is useful in the solution of complex models of system behavior. The authors have chosen two examples from the recent literature to illustrate the power and scope of this technique. They also demonstrate how folding of the generalized stochastic Petri net models for these two examples is useful in obtaining efficiently solvable, approximate models (bounding models). >
123 citations
Book•
22 Jul 1988
TL;DR: The theory of the processes of concurrent systems is studied using partiallyordered sets based on Petri net theory and general properties of posets and their relations with properties of concurrent system properties are examined.
Abstract: The theory of the processes of concurrent systems is studied using partiallyordered sets The study is based on Petri net theory General properties of posets and their relations with properties of concurrent systems are examined
TL;DR: The proposed net model offers a syntactical variant of Horn clause logic and has two distinctions from other existing schemes for the logic programs: representation formalism and the deduction method.
Abstract: A predicate/transition net model for a subset of Horn clause logic programs is presented. The syntax, transformation procedure, semantics, and deduction process for the net model are discussed. A possible parallel implementation for the net model is described, which is based on the concepts of communicating processes and relations. The proposed net model offers a syntactical variant of Horn clause logic and has two distinctions from other existing schemes for the logic programs: representation formalism and the deduction method. The net model provides an approach towards the solutions of the separation of logic from control and the improvement of the execution efficiency through parallel processing for the logic programs. The abstract nature of the net model also lends itself to different implementation strategies. >
TL;DR: A computer marking concept is introduced that allows a considerable reduction of the number of states and induces a correct grouping of states in the Markov-domain SHLPN models of multiprocessor systems.
Abstract: A class of stochastic Petri nets called stochastic high-level Petri nets (SHLPNs) is proposed. SHLPNs are high-level Petri nets augmented with exponentially distributed firing times. SHLPNs generally lead to models with a smaller state space. A computer marking concept is introduced that allows a considerable reduction of the number of states and induces a correct grouping of states in the Markov-domain SHLPN models of multiprocessor systems. The main advantage of modeling homogeneous systems using SHLPNs is that the resulting models are simpler and more intuitive and have a smaller number of states, as shown by examples. >
03 Jan 1988
TL;DR: A taxonomy of process abstraction methods is presented in an effort to characterize the fundamental concepts of level traversal and some observations on the future ofprocess abstraction in modeling are given.
Abstract: The concept of process abstraction, which allows simulationists to construct models composed of a set of interconnected levels, is discussed. Each level in the network represents the process at some given level of abstraction and is encoded using a model type (e.g. Petri net, automaton, data flow graph) appropriate to that level. An example process composed of articulated figures around a circular table is presented. After the process is formally defined at each level, the abstraction relationships between levels are discussed. A taxonomy of process abstraction methods is presented in an effort to characterize the fundamental concepts of level traversal. The application involving the animation of the process is described within the context of the HIRES simulation language that was constructed specifically to simulate and analyze multilevel simulations. Textual and graphical examples of HIRES output are included. Finally, some observations on the future of process abstraction in modeling are given. >
05 Jul 1988
TL;DR: The results provide a formal basis for expressing the semantics of concurrent languages in terms of Petri nets and an understanding of concurrency in Terms of algebraic structures over graphs and categories that should apply to other models and contribute to the conceptual unification of concurrence.
Abstract: The composition and extraction mechanisms of Petri nets are at present inadequate. This problem is solved by viewing place/transition Petri nets as ordinary, directed graphs equipped with two algebraic operations corresponding to parallel and sequential composition of transitions. A distributive law between the two operations captures a basic fact about concurrency. Novel morphisms are defined, mapping single, atomic transitions into whole computations, thus relating system descriptions at different levels of abstraction. Categories equipped with products and coproducts (corresponding to parallel and nondeterministic compositions) are introduced for Petri nets with and without initial markings. It is briefly indicated how the approach yields function spaces and novel interpretations of duality and invariants. The results provide a formal basis for expressing the semantics of concurrent languages in terms of Petri nets and an understanding of concurrency in terms of algebraic structures over graphs and categories that should apply to other models and contribute to the conceptual unification of concurrency. >
29 Aug 1988
TL;DR: This work shows how the intuitive causal dependencies in a CCS program are represented via the net semantics via the usual interleaving semantics.
Abstract: A non-interleaving semantics for a subset of CCS using finite place/transition-systems is presented. Straightforward constructions on nets for CCS operations are given. When restricting the language appropriately (no restriction and relabelling, only guarded choice), these operations yield a net semantics with a clear distinction of concurrency and nondeterminism. It is shown that the usual interleaving semantics is retrievable from the net semantics. Partial order semantics and equivalence notions for labelled P/T-systems are discussed. This shows how the intuitive causal dependencies in a CCS program are represented via the net semantics.
01 Oct 1988
TL;DR: In this paper, a polynomial algorithm was proposed to compute the earliest schedule of a Petri net sequence and a graph called earliest state graph was introduced for bounded Petri nets.
Abstract: In this paper, we define Timed Petri Net schedules and study some of their properties. We prove that the set of schedules issued from a firable sequence of the underlying Petri net has a minimum element we call earliest schedule of the sequence. We then propose a polynomial algorithm to compute it. In order to study earliest schedules, we introduce next a graph we call earliest state graph. Finally, for bounded Petri nets, we prove that earliest schedules issued from periodic infinite sequences are K-periodic and constitute a dominant subset.
TL;DR: A framework for automated static analysis of distributed programs written in Ada aimed at discovery of a program's potential tasking behavior, that is, behavior in terms of tasking-related issues.
TL;DR: Event-related control is considered in which process and related process control can be described by states and transitions that can be represented concisely by a Petri net (PN).
Abstract: Event-related control is considered in which process and related process control can be described by states and transitions that can be represented concisely by a Petri net (PN). Both process and related process control systems are event-related, causal, and concurrent and define a special type of PN using a few primitives that are assembled to form a net for which structural and dynamic invariants apply. The PNs can be used for a general approach to event-related process control in simulating, checking, debugging, and stating the quantitative deviations from the ideal solution for any given process control system. The technique can be applied to continuous or discrete processes, and provides formal checks at all development stages. It allows for components with nonideal behavior and yields numerical performance criteria. The invariants allow the PN to be structured in such a way that even complex process control systems become manageable. Examples are presented for the control tasks in an electrical substation. >
07 Dec 1988
TL;DR: In this paper, a Petri-net-based intelligent controller for fault detection and diagnosis in automated manufacturing systems is presented, where the authors assume that local controller and diagnostic systems exist for subsystem-level fault detection.
Abstract: The authors develop a controller methodology for fault detection and diagnosis using Petri nets and fault trees in automated manufacturing systems. The controller has two levels. At the first level there are dedicated diagnostic systems for each of the subsystems, such as machine centers, robots, conveyers, etc. At the second level there is an intelligent controller monitoring the part flow and coordinating the local diagnostic systems and controllers. The authors assume that local controller and diagnostic systems exist for subsystem-level fault detection and diagnosis, and they present a Petri-net-based intelligent controller for system-level fault detection and diagnosis. The authors also describe fault-free-based diagnostics. >
TL;DR: The use of Petri nets to represent fault trees is discussed and a more general and useful method to study the dynamic behavior of the model at various levels of abstraction is examined.
Abstract: The use of Petri nets to represent fault trees is discussed. Using reachability and other analytic properties of Petri nets, a more general and useful method to study the dynamic behavior of the model at various levels of abstraction is examined. The problems of fault-detection and propagation are discussed. For simplicity, only coherent fault trees are considered. However, the representation and analysis techniques are general and can be used for noncoherent fault trees. >
01 Jun 1988
TL;DR: This paper presents the generalization to the coloured nets of the most efficient reductions defined by Berthelot for Petri nets, and defines extensions of the implicit place transformation and the pre and post agglomeration of transitions.
Abstract: This paper presents the generalization to the coloured nets of the most efficient reductions defined by Berthelot for Petri nets. First, a generalization methodology is given that is independent from the reduction one wants to generalize. Then based on that methodology, we define extensions of the implicit place transformation and the pre and post agglomeration of transitions. For each reduction we prove that the reduced net has exactly the same properties as the original net. Finally we completely reduce an improved model of the data base management with multiple copies, thus showing its correctness.
01 Oct 1988
TL;DR: Quality criteria for implementations are specified and a variety of implementations of finite place/transition systems is discussed and the programs are formulated in Occam.
Abstract: In order to compare different distributed software implementations of the token game we start out from an explicitly defined basis, called the process paradigm. Quality criteria for implementations are specified and a variety of implementations of finite place/transition systems is discussed. The programs are formulated in Occam.
01 Apr 1988-International Journal of Human-computer Studies \/ International Journal of Man-machine Studies
TL;DR: Petri nets are identified as possible candidates for a modelling technique for dialogues on the basis of their applicability to concurrent, asynchronous systems and extended to nested Petri nets, allowing transitions to invoke subnets.
Abstract: The requirements of man-machine dialogue-specification techniques are examined. Petri nets are identified as possible candidates for a modelling technique for dialogues on the basis of their applicability to concurrent, asynchronous systems. Labelled Petri nets are extended to nested Petri nets, allowing transitions to invoke subnets. It is shown that this extension allows nested Petri nets to generate at least the set of context-free languages. Further extensions are made to simplify the modelling of input and output in the user interface, resulting in input-output nets. Transitions labelled by error conditions and meta functions on nets are introduced to increase the usability of the model. Finally, the use of the model is demonstrated by modelling a small hypothetical command language.
TL;DR: In this article, distributed artificial intelligence is applied to the real-time planning and control of flexible manufacturing systems (FMS) consisting of asynchronous manufacturing cells, where a knowledge-based approach is used to determine the course of action, resource sharing, and processor assignments.
Abstract: This article applied distributed artificial intelligence to the real-time planning and control of flexible manufacturing systems (FMS) consisting of asynchronous manufacturing cells. A knowledge-based approach is used to determine the course of action, resource sharing, and processor assignments. Within each cell there is an embedded automatic planning system that executes dynamic scheduling and supervises manufacturing operations. Because of the decentralized control, real-time task assignments are carried out by a negotiation process among cell hosts. The negotiation process is modeled by augmented Petri nets —the combination of production rules and Petri nets—and is excuted by a distributed, rule-based algorithm.
TL;DR: Several new classes of Petri nets are defined by structural conditions related to directed circuits, where a necessary and sufficient condition for reachability is obtained for trap circuit Petrinets (TC nets), where a Petri net is called a TC net if the set of places on any directed circuit forms a trap.
Abstract: The central issue of this paper is to find a class of Petri nets that a necessary and sufficient condition for reachability is obtainable. For this purpose, several new classes of Petri nets are defined by structural conditions related to directed circuits. A necessary and sufficient condition for reachability is obtained for trap circuit Petri nets (TC nets), where a Petri net is called a TC net if the set of places on any directed circuit forms a trap, and for deadlock circuit Petri nets (DC nets), where a Petri net is called a DC net if the set of places on any directed circuit forms a deadlock. The class of TC nets is a subclass of normal Petri nets. For normal Petri nets, a sufficient condition for reachability is obtained. Reachability for any conflict-free Petri net can be decided by finding a legal firing sequence for a finite number of minimal solutions of the state equation. This property also holds for larger classes of Petri nets. These are a class of non-decreasing circuit Petri nets (NDC nets), where a Petri net is called an NDC net if the number of tokens on any directed circuit is not decreased by any firing of transitions, and a class of non-increasing circuit Petri nets (NIC nets), where a Petri net is called an NIC net if the number of tokens on any directed circuit is non increased by any firing of transitions. The class of NDC nets and the class of NIC nets are subclasses of TC nets and DC nets, respectively.
01 Oct 1988
TL;DR: PRETOB is an object-oriented Computer Aided Software Engineering system based on high level Petri nets called PROT nets that addresses discrete event dynamic systems, such as process control systems and communication protocols.
Abstract: This paper presents PROTOB, an object-oriented Computer Aided Software Engineering system based on high level Petri nets called PROT nets. It consists of several tools supporting specification, modelling and prototyping activities within the framework of the operational software life cycle paradigm. As its major application area it addresses discrete event dynamic systems, such as process control systems and communication protocols.
13 Jan 1988
TL;DR: The thesis of this paper is that while induction using equational term-rewriting holds great promise, inductionless induction does not and it is argued that for reasoning about abstract data types traditional induction methods are usually superior.
Abstract: Rewriting techniques have been used to reason about a variety of topics related to programming languages, e.g., abstract data types, Petri Nets, FP programs, and data bases. They have also been used in the implementation and definition of a variety of programming languages.At the 1980 POPL Conference, David Musser proposed a new method of proving inductive properties of abstract data types. Since that time, this method, which came to be called inductionless induction, has attracted considerable attention. Numerous applications and improvements have been proposed and several implementations described. However, little or no work has appeared that questions the basic utility of the idea.The thesis of this paper is that while induction using equational term-rewriting holds great promise, inductionless induction does not. More specifically, we argue that for reasoning about abstract data types traditional inductive methods are usually superior.
Proceedings Article•
01 Jan 1988
TL;DR: In this paper, an attempt is made to cast labeled Petri nets and other models in an algebraic framework, and a category of labeled nets is presented, and its categorical constructions are used to establish a compositional proof system.
Abstract: An attempt is made to cast labeled Petri nets and other models in an algebraic framework. One aim is to utilize the framework of categorical l to cast labeled Petri nets and other models in an algebraic framework. The other aim is to utilize the framework of categorical logic to systematize specification languages and the derivation of proof systems for parallel processes. A category of labeled nets is presented, and its categorical constructions are used to establish a compositional proof system. A category of properties of nets is used in forming the proof system.<>
TL;DR: The DYLAM technique is shown to present significant advantages, especially for developing stochastic models of dynamic systems, and therefore is a powerful aid for the design of decision support systems to assist the operator in the control of hazardous processes.