Verification of priced and timed extensions of Petri Nets with multile instances

Tesis inédita de la Universidad Complutense de Madrid, Facultad de Informática, Departamento de Sistemas Informáticos y Computación, leída el 25-01-2016Las redes de Petri son un lenguaje formal muy adecuado para la modelizacíon, ańalisis y verificacíon de sistemas concurrentes con infinitos estados. En particular, son muy apropiadas para estudiar las propiedades de seguridad de dichos sistemas, dadas sus buenas propiedades de decidibilidad. Sin embargo, en muchas ocasiones las redes de Petri carecen de la expresividad necesaria para representar algunas caracteŕısticas fundamentales de los sistemas que se manejan hoy en d́ıa, como el manejo de tiempo real, costes reales, o la presencia de varios procesos con un ńumero no acotado de estados ejecut́andose en paralelo. En la literatura se han definido y estudiado algunas extensiones de las redes de Petri para la representaci ́on de las caracteŕısticas anteriores. Por ejemplo, las “Redes de Petri Temporizadas” [83, 10](TPN) incluyen el manejo de tiempo real y las ν-redes de Petri [78](ν-PN) son capaces de representar un ńumero no acotado de procesos con infinitos estados ejecut́andose concurrentemente. En esta tesis definimos varias extensiones que réunen estas dos caracteŕısticas y estudiamos sus propiedades de decidibilidad. En primer lugar definimos las “ν-Redes de Petri Temporizadas”, que réunen las caracteŕısticas expresivas de las TPN y las ν-PN. Este nuevo modelo es capaz de representar sistemas con un ńumero no acotado de procesos o instancias, donde cada proceso es representado por un nombre diferente, y tiene un ńumero no acotado de relojes reales. En este modelo un reloj de una instancia debe satisfacer ciertas condiciones (pertenecer a un intervalo dado) para formar parte en el disparo de una transicíon. Desafortunadamente, demostramos que la verificacíon de propiedades de seguridad es indecidible para este modelo...The model of Petri nets is a formal modeling language which is very suitable for the analysis and verification of infinite-state concurrent systems. In particular, due to its good decidability properties, it is very appropriate to study safety properties over such systems. However, Petri nets frequently lack the expressiveness to represent several essential characteristics of nowadays systems such as real time, real costs, or the managing of several parallel processes, each with an unbounded number of states. Several extensions of Petri nets have been defined and studied in the literature to fix these shortcomings. For example, Timed Petri nets [83, 10] deal with real time and ν-Petri nets [78] are able to represent an unbounded number of different infinite-state processes running concurrently. In this thesis we define new extensions which encompass these two characteristics, and study their decidability properties. First, we define Timed ν-Petri nets by joining together Timed Petri nets and ν-Petri nets. The new model represents systems in which each process (also called instance) is represented by a different pure name, and it is endowed with an unbounded number of clocks. Then, a clock of an instance must satisfy certain given conditions (belonging to a given interval) in order to take part in the firing of a transition. Unfortunately, we prove that the verification of safety properties is undecidable for this model. In fact, it is undecidable even if we only consider two clocks per process. We restrict this model and define Locally-Synchronous ν-Petri nets by considering only one clock per instance, and successfully prove the decidability of safety properties for this model. Moreover, we study the expressiveness of Locally-Synchronous ν-Petri nets and prove that it is the most expressive non Turing-complete extension of Petri nets with respect to the languages they accept...Depto. de Sistemas Informáticos y ComputaciónFac. de InformáticaTRUEunpu

Seventh Workshop and Tutorial on Practical Use of Coloured Petri Nets and the CPN Tools, Aarhus, Denmark, October 24-26, 2006

This booklet contains the proceedings of the Seventh Workshop on Practical Use of Coloured Petri Nets and the CPN Tools, October 24-26, 2006. The workshop is organised by the CPN group at the Department of Computer Science, University of Aarhus, Denmark. The papers are also available in electronic form via the web pages: http://www.daimi.au.dk/CPnets/workshop0

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Computer Aided Verification

The open access two-volume set LNCS 12224 and 12225 constitutes the refereed proceedings of the 32st International Conference on Computer Aided Verification, CAV 2020, held in Los Angeles, CA, USA, in July 2020.* The 43 full papers presented together with 18 tool papers and 4 case studies, were carefully reviewed and selected from 240 submissions. The papers were organized in the following topical sections: Part I: AI verification; blockchain and Security; Concurrency; hardware verification and decision procedures; and hybrid and dynamic systems. Part II: model checking; software verification; stochastic systems; and synthesis. *The conference was held virtually due to the COVID-19 pandemic

A semantic Bayesian network for automated share evaluation on the JSE

Advances in information technology have presented the potential to automate investment decision making processes. This will alleviate the need for manual analysis and reduce the subjective nature of investment decision making. However, there are different investment approaches and perspectives for investing which makes acquiring and representing expert knowledge for share evaluation challenging. Current decision models often do not reflect the real investment decision making process used by the broader investment community or may not be well-grounded in established investment theory. This research investigates the efficacy of using ontologies and Bayesian networks for automating share evaluation on the JSE. The knowledge acquired from an analysis of the investment domain and the decision-making process for a value investing approach was represented in an ontology. A Bayesian network was constructed based on the concepts outlined in the ontology for automatic share evaluation. The Bayesian network allows decision makers to predict future share performance and provides an investment recommendation for a specific share. The decision model was designed, refined and evaluated through an analysis of the literature on value investing theory and consultation with expert investment professionals. The performance of the decision model was validated through back testing and measured using return and risk-adjusted return measures. The model was found to provide superior returns and risk-adjusted returns for the evaluation period from 2012 to 2018 when compared to selected benchmark indices of the JSE. The result is a concrete share evaluation model grounded in investing theory and validated by investment experts that may be employed, with small modifications, in the field of value investing to identify shares with a higher probability of positive risk-adjusted returns

FORMAL ANALYSIS OF WEB SERVICE COMPOSITION

Ph.DDOCTOR OF PHILOSOPH