Pub Date : 2001-09-11DOI: 10.1109/PNPM.2001.953354
G. Franceschinis, Claudio Bertoncello, G. Bruno, G. L. Vaschetti, Antonio Pigozzi
In this paper, we describe the experience in modeling contact centers through stochastic well-formed net (SWN) models in an industry-driven project. The paper describes the problem and shows some of the questions that SWN models could answer, but it also highlights some limitations of the formalism and of the tools used for the analysis. It then discusses the work done to rationalize the model construction and analysis tasks, setting up a methodology and a library of reusable submodels to allow quick development of models of other systems in the same class. We also discuss the acceptance of the proposed approach in the company.
{"title":"SWN models of a contact center: a case study","authors":"G. Franceschinis, Claudio Bertoncello, G. Bruno, G. L. Vaschetti, Antonio Pigozzi","doi":"10.1109/PNPM.2001.953354","DOIUrl":"https://doi.org/10.1109/PNPM.2001.953354","url":null,"abstract":"In this paper, we describe the experience in modeling contact centers through stochastic well-formed net (SWN) models in an industry-driven project. The paper describes the problem and shows some of the questions that SWN models could answer, but it also highlights some limitations of the formalism and of the tools used for the analysis. It then discusses the work done to rationalize the model construction and analysis tasks, setting up a methodology and a library of reusable submodels to allow quick development of models of other systems in the same class. We also discuss the acceptance of the proposed approach in the company.","PeriodicalId":364695,"journal":{"name":"Proceedings 9th International Workshop on Petri Nets and Performance Models","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2001-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114766553","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-09-11DOI: 10.1109/PNPM.2001.953373
G. Clark, T. Courtney, David Daly, D. Deavours, Salem Derisavi, J. Doyle, W. Sanders, P. Webster
Despite the development of many modeling formalisms and model solution methods, most tool implementations support only a single formalism. Furthermore, models expressed in the chosen formalism cannot be combined with models expressed in other formalisms. This monolithic approach both limits the usefulness of such tools to practitioners, and hampers modeling research, since it is difficult to compare new and existing formalisms and solvers. This paper describes the method that a new modeling tool, called Mobius, uses to eliminate these limitations. Mobius provides an infrastructure to support multiple interacting formalisms and solvers, and is extensible in that new formalisms anal solvers can, be added to the tool without changing those already implemented. Mobius provides this capability through the use of an abstract functional interface, which provides a formalism-independent interface to models. This allows models expressed in multiple formalisms to interact with each other, and with multiple solvers.
{"title":"The Mobius modeling tool","authors":"G. Clark, T. Courtney, David Daly, D. Deavours, Salem Derisavi, J. Doyle, W. Sanders, P. Webster","doi":"10.1109/PNPM.2001.953373","DOIUrl":"https://doi.org/10.1109/PNPM.2001.953373","url":null,"abstract":"Despite the development of many modeling formalisms and model solution methods, most tool implementations support only a single formalism. Furthermore, models expressed in the chosen formalism cannot be combined with models expressed in other formalisms. This monolithic approach both limits the usefulness of such tools to practitioners, and hampers modeling research, since it is difficult to compare new and existing formalisms and solvers. This paper describes the method that a new modeling tool, called Mobius, uses to eliminate these limitations. Mobius provides an infrastructure to support multiple interacting formalisms and solvers, and is extensible in that new formalisms anal solvers can, be added to the tool without changing those already implemented. Mobius provides this capability through the use of an abstract functional interface, which provides a formalism-independent interface to models. This allows models expressed in multiple formalisms to interact with each other, and with multiple solvers.","PeriodicalId":364695,"journal":{"name":"Proceedings 9th International Workshop on Petri Nets and Performance Models","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2001-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134538762","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-09-11DOI: 10.1109/PNPM.2001.953357
G. Balbo, S. C. Bruell, M. Sereno
We show that a particular class of Generalized Stochastic Petri Nets have stationary probabilities that exhibit a product form. Efficient solution algorithms can be developed for the computation of the performance indices of such Product-Form GSPNs. These algorithms avoid the generation of the underlying state space. Hence, large PF-GSPN models can now be effectively studied.
{"title":"Embedded processes in Generalized Stochastic Petri Nets","authors":"G. Balbo, S. C. Bruell, M. Sereno","doi":"10.1109/PNPM.2001.953357","DOIUrl":"https://doi.org/10.1109/PNPM.2001.953357","url":null,"abstract":"We show that a particular class of Generalized Stochastic Petri Nets have stationary probabilities that exhibit a product form. Efficient solution algorithms can be developed for the computation of the performance indices of such Product-Form GSPNs. These algorithms avoid the generation of the underlying state space. Hence, large PF-GSPN models can now be effectively studied.","PeriodicalId":364695,"journal":{"name":"Proceedings 9th International Workshop on Petri Nets and Performance Models","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2001-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125245475","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-09-11DOI: 10.1109/PNPM.2001.953369
J. Hillston, L. Recalde, M. Ribaudo, M. Suárez
This paper presents some transformation techniques from bounded SPN systems to corresponding SPA models, preserving concurrency. Initially, a simple algorithm is introduced, showing that the obtained SPA models simulate the net systems. Then the algorithm is improved in order to keep more of the net structure, when possible. For the case of non ordinary net systems the SPA language is extended by introducing a new cooperation operator.
{"title":"A comparison of the expressiveness of SPA and bounded SPN models","authors":"J. Hillston, L. Recalde, M. Ribaudo, M. Suárez","doi":"10.1109/PNPM.2001.953369","DOIUrl":"https://doi.org/10.1109/PNPM.2001.953369","url":null,"abstract":"This paper presents some transformation techniques from bounded SPN systems to corresponding SPA models, preserving concurrency. Initially, a simple algorithm is introduced, showing that the obtained SPA models simulate the net systems. Then the algorithm is improved in order to keep more of the net structure, when possible. For the case of non ordinary net systems the SPA language is extended by introducing a new cooperation operator.","PeriodicalId":364695,"journal":{"name":"Proceedings 9th International Workshop on Petri Nets and Performance Models","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2001-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131027523","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-09-11DOI: 10.1109/PNPM.2001.953372
Nicolas Rivière, B. Pradin-Chezalviel, R. Valette
The first aim of this paper is to characterize marking reachability within scenarios defined on t-time Petri nets. This reachability can be structural (does not depend on the enabling durations), necessary (for all the possible values of the enabling durations within some given enabling intervals) or possible (for some values of the enabling durations). This approach is based on the computation of sojourn times of tokens in places by means of the construction of proof trees in linear logic. The second aim is to illustrate the fact that these sojourn times can also be used to analyze the conflicts between two scenarios, taking into account all the temporal constraints. In some cases, one of the scenarios will invalidate the other one: the temporal constraints are such that this scenario will never occur.
{"title":"Reachability and temporal conflicts in t-time Petri nets","authors":"Nicolas Rivière, B. Pradin-Chezalviel, R. Valette","doi":"10.1109/PNPM.2001.953372","DOIUrl":"https://doi.org/10.1109/PNPM.2001.953372","url":null,"abstract":"The first aim of this paper is to characterize marking reachability within scenarios defined on t-time Petri nets. This reachability can be structural (does not depend on the enabling durations), necessary (for all the possible values of the enabling durations within some given enabling intervals) or possible (for some values of the enabling durations). This approach is based on the computation of sojourn times of tokens in places by means of the construction of proof trees in linear logic. The second aim is to illustrate the fact that these sojourn times can also be used to analyze the conflicts between two scenarios, taking into account all the temporal constraints. In some cases, one of the scenarios will invalidate the other one: the temporal constraints are such that this scenario will never occur.","PeriodicalId":364695,"journal":{"name":"Proceedings 9th International Workshop on Petri Nets and Performance Models","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2001-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121889898","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-09-11DOI: 10.1109/PNPM.2001.953371
M. Boyer, M. Diaz
This paper discusses and formalises the benefits of using multiple enabled transitions for extensions of Petri nets having quantitative notions of time. It also points out that what could be thought as a straightforward extension actually implies some subtle underlying semantic choices. As an example, a complete semantics for Merlin's (1974) time Petri nets is defined, based on the threshold notion.
{"title":"Multiple enabledness of transitions in Petri nets with time","authors":"M. Boyer, M. Diaz","doi":"10.1109/PNPM.2001.953371","DOIUrl":"https://doi.org/10.1109/PNPM.2001.953371","url":null,"abstract":"This paper discusses and formalises the benefits of using multiple enabled transitions for extensions of Petri nets having quantitative notions of time. It also points out that what could be thought as a straightforward extension actually implies some subtle underlying semantic choices. As an example, a complete semantics for Merlin's (1974) time Petri nets is defined, based on the threshold notion.","PeriodicalId":364695,"journal":{"name":"Proceedings 9th International Workshop on Petri Nets and Performance Models","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2001-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126968670","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-09-11DOI: 10.1109/PNPM.2001.953370
H. Macià, V. Valero, David de Frutos-Escrig
In this paper we present a stochastic extension of finite PBC, sPBC in which actions have a stochastic delay associated, which is taken from a negative exponential distribution. We define for the language both an operational and a denotational semantics, using a class of labelled stochastic Petri net as supporting values. In this paper we restrict our attention to finite sPBC, i.e. we consider neither the iteration operator nor recursive definition of processes.
{"title":"SPBC: a Markovian extension of finite Petri box calculus","authors":"H. Macià, V. Valero, David de Frutos-Escrig","doi":"10.1109/PNPM.2001.953370","DOIUrl":"https://doi.org/10.1109/PNPM.2001.953370","url":null,"abstract":"In this paper we present a stochastic extension of finite PBC, sPBC in which actions have a stochastic delay associated, which is taken from a negative exponential distribution. We define for the language both an operational and a denotational semantics, using a class of labelled stochastic Petri net as supporting values. In this paper we restrict our attention to finite sPBC, i.e. we consider neither the iteration operator nor recursive definition of processes.","PeriodicalId":364695,"journal":{"name":"Proceedings 9th International Workshop on Petri Nets and Performance Models","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2001-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114895510","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-09-11DOI: 10.1109/PNPM.2001.953352
M. Marsan, M. Gribaudo, M. Meo, M. Sereno
In this paper we model a wireless Internet access system based on the GSM/GPRS (Global System for Mobile communications/General Packet Radio Service) technology, with three different Petri net-based paradigms: Generalized Stochastic Petri Nets (GSPNs), Deterministic and Stochastic Petri Nets (DSPNs), and Fluid Stochastic Petri Nets (FSPNs). We show that all three Petri net-based paradigms provide very similar performance predictions for some of the considered realistic configurations of GSM/GPRS systems, and for some of the performance metrics of interest. This proves that FSPNs can be an adequate tool for the performance analysis of wireless Internet access systems, and allow the investigation of large system configurations, thanks to the availability of very efficient solution algorithms for FSPN models. However, we also show that in other cases (which can be clearly characterized), the performance predictions generated by FSPN models may become quite optimistic, and thus not suitable for a careful design and planning of GSM/GPRS systems. In those cases, both DSPNs and GSPNs can provide a viable modeling alternative, at least in the case of medium scale systems.
{"title":"On Petri Net-based modeling paradigms for the performance analysis of wireless Internet accesses","authors":"M. Marsan, M. Gribaudo, M. Meo, M. Sereno","doi":"10.1109/PNPM.2001.953352","DOIUrl":"https://doi.org/10.1109/PNPM.2001.953352","url":null,"abstract":"In this paper we model a wireless Internet access system based on the GSM/GPRS (Global System for Mobile communications/General Packet Radio Service) technology, with three different Petri net-based paradigms: Generalized Stochastic Petri Nets (GSPNs), Deterministic and Stochastic Petri Nets (DSPNs), and Fluid Stochastic Petri Nets (FSPNs). We show that all three Petri net-based paradigms provide very similar performance predictions for some of the considered realistic configurations of GSM/GPRS systems, and for some of the performance metrics of interest. This proves that FSPNs can be an adequate tool for the performance analysis of wireless Internet access systems, and allow the investigation of large system configurations, thanks to the availability of very efficient solution algorithms for FSPN models. However, we also show that in other cases (which can be clearly characterized), the performance predictions generated by FSPN models may become quite optimistic, and thus not suitable for a careful design and planning of GSM/GPRS systems. In those cases, both DSPNs and GSPNs can provide a viable modeling alternative, at least in the case of medium scale systems.","PeriodicalId":364695,"journal":{"name":"Proceedings 9th International Workshop on Petri Nets and Performance Models","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2001-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128557095","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-09-11DOI: 10.1109/PNPM.2001.953365
A. Horváth, M. Telek
The time domain analysis of non-Markovian stochastic Petri nets (NMSPNs) with preemptive repeat identical (pri) type transitions is considered in this paper. The set of time domain equations describing the evolution of the marking process is provided. The relation of the time domain and the formerly available transform domain description is discussed. Based on the time domain description of the process a simple numerical procedure is provided to analyze the transient behavior. Two examples are calculated to illustrate the proposed numerical method.
{"title":"Time domain analysis of NMSPN with PRI transitions","authors":"A. Horváth, M. Telek","doi":"10.1109/PNPM.2001.953365","DOIUrl":"https://doi.org/10.1109/PNPM.2001.953365","url":null,"abstract":"The time domain analysis of non-Markovian stochastic Petri nets (NMSPNs) with preemptive repeat identical (pri) type transitions is considered in this paper. The set of time domain equations describing the evolution of the marking process is provided. The relation of the time domain and the formerly available transform domain description is discussed. Based on the time domain description of the process a simple numerical procedure is provided to analyze the transient behavior. Two examples are calculated to illustrate the proposed numerical method.","PeriodicalId":364695,"journal":{"name":"Proceedings 9th International Workshop on Petri Nets and Performance Models","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2001-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121880238","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-09-11DOI: 10.1109/PNPM.2001.953366
Rob Jones, G. Ciardo
We present a novel stochastic Petri net formalism where both discrete and continuous phase-type firing delays can appear simultaneously in the same model. By capturing non-Markovian behavior in discrete or continuous time, as appropriate, the formalism affords higher modeling fidelity. Alone, discrete or continuous phase-type Petri nets have simple underlying Markov chains, but mixing the two complicates matters. We show that, in a mixed model where discrete-time transitions are synchronized, the underlying process is semi-regenerative and we can employ Markov renewal theory to formulate stationary or time-dependent solutions. Also noteworthy are the computational trade-offs between the so-called embedded and subordinate Markov chains, which we employ to improve the overall solution efficiency. We present a preliminary stationary solution method that shows promise in terms of time and space efficiency and demonstrate it on an aeronautical data link system application.
{"title":"On phased delay stochastic Petri nets: definition and an application","authors":"Rob Jones, G. Ciardo","doi":"10.1109/PNPM.2001.953366","DOIUrl":"https://doi.org/10.1109/PNPM.2001.953366","url":null,"abstract":"We present a novel stochastic Petri net formalism where both discrete and continuous phase-type firing delays can appear simultaneously in the same model. By capturing non-Markovian behavior in discrete or continuous time, as appropriate, the formalism affords higher modeling fidelity. Alone, discrete or continuous phase-type Petri nets have simple underlying Markov chains, but mixing the two complicates matters. We show that, in a mixed model where discrete-time transitions are synchronized, the underlying process is semi-regenerative and we can employ Markov renewal theory to formulate stationary or time-dependent solutions. Also noteworthy are the computational trade-offs between the so-called embedded and subordinate Markov chains, which we employ to improve the overall solution efficiency. We present a preliminary stationary solution method that shows promise in terms of time and space efficiency and demonstrate it on an aeronautical data link system application.","PeriodicalId":364695,"journal":{"name":"Proceedings 9th International Workshop on Petri Nets and Performance Models","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2001-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122484307","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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