315 research outputs found
Second Workshop on Practical Use of Coloured Petri Nets and Design/CPN.
This report contains the proceedings of the Second Workshop on Practical Use of Coloured Petri Nets and Design/CPN, October 13-15, 1999. The workshop was organised by the CPN group at the Department of Computer Science at the University of Aarhus, Denmark. The individual papers are available in electronic form via the web pages: http://www.daimi.au.dk/CPnets/workshop99
Analysis of Two-Layer Protocols: DCCP Simultaneous-Open and Hole Punching Procedures
The simultaneous-open procedure of the Datagram Congestion Control Protocol (DCCP), RFC 5596, was published in September 2009. Its design aims to overcome DCCP weaknesses when the Server is behind a middle box, such as Network Address Translators or firewalls. The original DCCP specification, RFC 4340, only allows the Client to initiate the call. The call request cannot reach the Server behind the middle box. A widely used solution to address this problem is called the hole punching technique. This technique requires the Server to initiate sending packets. Using Coloured Petri Nets (CPN) this paper models and analyses the DCCP procedure specified in RFC 5596. However, the difficulty is that detailed modelling of the address translation is also required. This causes state space explosion. We alleviate the state explosion using prioritized transitions and the sweep-line technique. Modelling and analysis approaches are discussed in the hope that it is helpful for others who wish to analyse similar protocols. Analysis results are also obtained for the simultaneous-open procedure specified in RFC 5596
A Polynomial Translation of pi-calculus FCPs to Safe Petri Nets
We develop a polynomial translation from finite control pi-calculus processes
to safe low-level Petri nets. To our knowledge, this is the first such
translation. It is natural in that there is a close correspondence between the
control flows, enjoys a bisimulation result, and is suitable for practical
model checking.Comment: To appear in special issue on best papers of CONCUR'12 of Logical
Methods in Computer Scienc
Reconciling a component and process view
In many cases we need to represent on the same abstraction level not only
system components but also processes within the system, and if for both
representation different frameworks are used, the system model becomes hard to
read and to understand. We suggest a solution how to cover this gap and to
reconcile component and process views on system representation: a formal
framework that gives the advantage of solving design problems for large-scale
component systems.Comment: Preprint, 7th International Workshop on Modeling in Software
Engineering (MiSE) at ICSE 201
Practical Use of High-level Petri Nets
This booklet contains the proceedings of the Workshop on Practical Use of High-level Petri Nets, June 27, 2000. The workshop is part of the 21st International Conference on Application and Theory of Petri Nets organised by the CPN group at the Department of Computer Science, University of Aarhus, Denmark. The workshop papers are available in electronic form via the web pages: http://www.daimi.au.dk/pn2000/proceeding
Computational modeling of the EGFR network elucidates control mechanisms regulating signal dynamics.
BACKGROUND: The epidermal growth factor receptor (EGFR) signaling pathway plays a key role in regulation of cellular growth and development. While highly studied, it is still not fully understood how the signal is orchestrated. One of the reasons for the complexity of this pathway is the extensive network of inter-connected components involved in the signaling. In the aim of identifying critical mechanisms controlling signal transduction we have performed extensive analysis of an executable model of the EGFR pathway using the stochastic pi-calculus as a modeling language. RESULTS: Our analysis, done through simulation of various perturbations, suggests that the EGFR pathway contains regions of functional redundancy in the upstream parts; in the event of low EGF stimulus or partial system failure, this redundancy helps to maintain functional robustness. Downstream parts, like the parts controlling Ras and ERK, have fewer redundancies, and more than 50% inhibition of specific reactions in those parts greatly attenuates signal response. In addition, we suggest an abstract model that captures the main control mechanisms in the pathway. Simulation of this abstract model suggests that without redundancies in the upstream modules, signal transduction through the entire pathway could be attenuated. In terms of specific control mechanisms, we have identified positive feedback loops whose role is to prolong the active state of key components (e.g., MEK-PP, Ras-GTP), and negative feedback loops that help promote signal adaptation and stabilization. CONCLUSIONS: The insights gained from simulating this executable model facilitate the formulation of specific hypotheses regarding the control mechanisms of the EGFR signaling, and further substantiate the benefit to construct abstract executable models of large complex biological networks.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are
Petri net based development of globally-asynchronous locally-synchronous distributed embedded systems
Dissertação para obtenção do Grau de Doutor em Engenharia Electrotécnica e de ComputadoresA model-based development approach (MBDA) for Globally-Asynchronous Locally-
Synchronous (GALS) Distributed Embedded Systems (DESs) is proposed. This approach
relies on the GALS-DESs specification through (low- or high-level) Petri net classes, which
ensure that the created models are GALS, locally deterministic, distributable, networkindependent,
and platform-independent and support their simulation, verification, and
implementation (using simulation, model-checking, and code generation tools). The use
of network- and platform-independent models enable the use of heterogeneous communication
networks to support the distributed components interaction and enable the use
of heterogeneous platforms to support the components and the communication nodes
implementation. To enable the proposed MBDA, Petri nets are extended with a set of the
concepts, most notably time-domains and asynchronous-channels. Algorithms to support
the verification of GALS-DES models and their decomposition into implementable
sub-models are also proposed. A tool chain framework (IOPT-tools) was extended with
this work proposals, supporting their validation and the GALS-DESs development.Fundação para a Ciência e a Tecnologia - grant ref. SFRH/BD/62171/200
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