In modern society services and support provided by computer-based systems have become ubiquitous and indeed have started to fund amentally alter the way people conduct their business. Moreover, it has become apparent that among the great variety of computer technologies available to potential users a crucial role will be played by concurrent systems. The reason is that many commonly occurring phenomena and computer applications are highly con current : typical examples include control systems, computer networks, digital hardware, business computing, and multimedia systems. Such systems are characterised by ever increasing complexity, which results when large num bers of concurrently active components interact. This has been recognised and addressed within the computing science community. In particular, sev eral form al models of concurrent systems have been proposed, studied, and applied in practice. This book brings together two of the most widely used formalisms for de scribing and analysing concurrent systems: Petri nets and process algebras. On the one hand , process algebras allow one to specify and reason about the design of complex concurrent computing systems by means of algebraic operators corresponding to common programming constructs. Petri nets, on the other hand, provide a graphical representation of such systems and an additional means of verifying their correctness efficiently, as well as a way of expressing properties related to causality and concurrency in system be haviour.

Paradigms of Concurrency: Observations, Behaviours, and Systems - a Petri Net View - Ryszard Janicki (McMaster University, CA) Jetty Kleijn (Leiden University, NL) Maciej Koutny (Newcastle University, UK) Lukasz Mikulski (Nicolaus Copernicus University, PL) Concurrency can be studied at different yet consistent levels of abstraction: from individual behavioural observations via more abstract concurrent histories that can be represented by causality structures capturing invariant dependencies between executed actions, to system level constructs such as Petri nets or process algebra expressions. Histories can then be understood as sets of closely related observations. Depending on the nature of the observed relationships between executed actions involved in a single concurrent history, one may identify different concurrency paradigms underpinned by different kinds of causality structures such as partial orders. This book studies fundamental mathematical abstractions to capture and relate observations, histories, and systems. In particular, taking a Petri net view, we present system models fitting various concurrency paradigms and their associated causality structures.

The 12th volume of ToPNoC contains revised and extended versions of a selection of the best workshop papers presented at the 37th International Conference on Application and Theory of Petri Nets and Concurrency, Petri Nets 2016, and the 16th International Conference on Application of Concurrency to System Design, ACSD 2016. It also contains one paper submitted directly to ToPNoC. The 9 papers cover a diverse range of topics including model checking and system verification, refinement, and synthesis; foundational work on specific classes of Petri nets; and innovative applications of Petri nets and other models of concurrency. Application areas covered in this volume are: security, service composition, databases, communication protocols, business processes, and distributed systems. Thus, this volume gives a good overview of ongoing research on concurrent systems and Petri nets.

The 11th volume of ToPNoC contains revised and extended versions of a selection of the best workshop papers presented at the 36th International Conference on Application and Theory of Petri Nets and Concurrency, Petri Nets 2015, and the 15th International Conference on Application of Concurrency to System Design, ACSD 2014. It also contains one paper submitted directly to ToPNoC. The 16 papers cover a diverse range of topics including model checking and system verification, refinement and synthesis; foundational work on specific classes of Petri nets; and innovative applications of Petri nets and other models of concurrency. Application areas covered in this volume are: security, service composition, communication protocols, business processes, distributed systems, and multi-agent systems. Thus, this volume gives a good overview of ongoing research on concurrent systems and Petri nets.

These Transactions publish archival papers in the broad area of Petri nets and other models of concurrency, ranging from theoretical work to tool support and industrial applications. ToPNoC issues are published as LNCS volumes, and hence are widely distributed and indexed. This Journal has its own Editorial Board which selects papers based on a rigorous two-stage refereeing process. ToPNoC contains: - Revised versions of a selection of the best papers from workshops and tutorials at the annual Petri net conferences - Special sections/issues within particular subareas (similar to those published in the Advances in Petri Nets series) - Other papers invited for publication in ToPNoC - Papers submitted directly to ToPNoC by their authors The 9th volume of ToPNoC contains revised and extended versions of a selection of the best workshop papers presented at the 34th International Conference on Application and Theory of Petri Nets and Concurrency (Petri Nets 2013) and the 13th International Conference on Application of Concurrency to System Design (ACSD 2013). It also contains one paper submitted directly to ToPNoC. The 8 papers cover a diverse range of topics including model checking and system verification, refinement and synthesis, foundational work on specific classes of Petri nets, and innovative applications of Petri nets and other models of concurrency. Application areas covered in this volume are: biological systems, communication protocols, business processes, distributed systems, and multi-agent systems. Thus, this volume gives a good view of ongoing concurrent systems and Petri nets research.

The 8th volume of ToPNoC contains revised and extended versions of a selection of the best workshop papers presented at the 33rd International Conference on Application and Theory of Petri Nets and Other Models of Concurrency (Petri Nets 2012). The 10 papers cover a diverse range of topics including model checking and system verification, refinement and synthesis, foundational work on specific classes of Petri nets, and innovative applications of Petri nets and other models of concurrency. Application areas covered in this volume are: biological systems, communication protocols, business processes, collaborative team work, and Petri net education. Thus this volume gives a good view of ongoing concurrent systems and Petri nets research.

These Transactions publish archival papers in the broad area of Petri nets and other models of concurrency, ranging from theoretical work to tool support and industrial applications. ToPNoC issues are published as LNCS volumes, and hence are widely distributed and indexed. This Journal has its own Editorial Board which selects papers based on a rigorous two-stage refereeing process. ToPNoC contains: - Revised versions of a selection of the best papers from workshops and tutorials at the annual Petri net conferences - Special sections/issues within particular subareas (similar to those published in the Advances in Petri Nets series) - Other papers invited for publication in ToPNoC - Papers submitted directly to ToPNoC by their authors The 7th volume of ToPNoC contains revised material from the 5th International Summer School "Advanced Course on Petri Nets", held in September 2010 in Rostock, Germany. The nine papers cover a diverse range of topics including modeling, verification, partial order semantics, and synthesis of Petri nets. In compliance with their origin as course material, the papers are written in survey or tutorial style and give a comprehensive overview of the state of the art in their respective areas.

This book constitutes the thoroughly refereed proceedings of the 23rd International Conference on Concurrency Theory, CONCUR 2012, held in Newcastle upon Tyne, UK, September 4-7, 2012. The 35 revised full papers presented together with 4 invited talks were carefully reviewed and selected from 97 submissions. The papers are organized in topics such as reachability analysis; qualitative and timed systems; behavioural equivalences; temporal logics; session types; abstraction; mobility and space in process algebras; stochastic systems; probabilistic systems; Petri nets and non-sequential semantics; verification; decidability.

In modern society services and support provided by computer-based systems have become ubiquitous and indeed have started to fund amentally alter the way people conduct their business. Moreover, it has become apparent that among the great variety of computer technologies available to potential users a crucial role will be played by concurrent systems. The reason is that many commonly occurring phenomena and computer applications are highly con current : typical examples include control systems, computer networks, digital hardware, business computing, and multimedia systems. Such systems are characterised by ever increasing complexity, which results when large num bers of concurrently active components interact. This has been recognised and addressed within the computing science community. In particular, sev eral form al models of concurrent systems have been proposed, studied, and applied in practice. This book brings together two of the most widely used formalisms for de scribing and analysing concurrent systems: Petri nets and process algebras. On the one hand , process algebras allow one to specify and reason about the design of complex concurrent computing systems by means of algebraic operators corresponding to common programming constructs. Petri nets, on the other hand, provide a graphical representation of such systems and an additional means of verifying their correctness efficiently, as well as a way of expressing properties related to causality and concurrency in system be haviour.

AccordingtoHolzmann 14], protocol speci?cationscomprise ?veelements: the service the protocol provides toits users; the set of messages that are exchanged between protocol entities; the format of each message; the rules governingm- sage exchange (procedures); and the assumptionsabout the environment in which the protocol is intended tooperate. In protocol standards documents, information related to the operatingenvironment isusually writteninformally andmayoccur in several di?erentplaces 37]. This informal speci?cation style canlead to misunderstandings andpossibly incompatible implementations. In contrast, executableformalmodelsrequireprecisespeci?cations oftheoperating environment. Ofparticularsigni?canceisthecommunicationmediumorchannel over which the protocol operates. Channelscan havedi?erent characteristics depending on the physical media (e. g. optical ?bre, copper, cable orunguided media (radio)) they employ. The characteristics also depend on the levelof the protocol inacomputer protocol architecture. Forexample, the link-leveloperates over a singlemedium, whereas the network, transport andapplication levelsmayoperate over a network, or network of networks such as the Internet, which couldemploy several di?erent physical media. Channels (such as satellite links) can be noisy resulting in bit errors in packets. To correct biterrors in packets, many importantprotocols (such the Internet's TransmissionControl Protocol 27]) use CyclicRedundancy Checks (CRCs) 28] to detect errors. On detectingan error, the receiver discards the packet andrelies on the sender to retransmit itforrecovery, known as Au- maticRepeatreQuest(ARQ) 28]. Thisisachievedbythereceiveracknowledging the receipt of good packets, andby the transmitter maintainingatimer. When the timer expires before an acknowledgementhasbeen received, the transmitter retransmits packets that havebeen sent but are as yet notacknowledged. It may also be possibleforpacketsto be lost due to routers in networks discarding packets when congested

This volume contains the proceedings of the 22nd International Conference on Application and Theory of Petri Nets. The aim of the Petri net conferences is to create a forum for discussing progress in the application and theory of Petri nets. Typically, the conferences have 100{150 participants { one third of these coming from industry while the rest are from universities and research institutions. The conferences always take place in the last week of June. This year the conference was organized jointly with the 2nd International Conference on Application of Concurrency to System Design (ICACSD 2001). The two conferences shared the invited lectures and the social program. The conference and a number of other activities are co-ordinated by a steering committee with the following members: G. Balbo (Italy), J. Billington (Aust- lia), G. De Michelis (Italy), C. Girault (France), K. Jensen (Denmark), S. - magai (Japan), T. Murata (USA), C.A. Petri (Germany; honorary member), W. Reisig (Germany), G. Rozenberg (The Netherlands; chairman), and M. Silva (Spain). Other activities before and during the 2001 conference included tool dem- strations, a meeting on \XML Based Interchange Formats for Petri Nets," - tensive introductory tutorials, two advanced tutorials on \Probabilistic Methods in Concurrency" and \Model Checking," and two workshops on \Synthesis of Concurrent Systems" and \Concurrency in Dependable Computing." The tu- rial notes and workshop proceedings are not published in these proceedings, but copies are available from the organizers.

The 16th volume of ToPNoC contains revised and extended versions of a selection of the best workshop and tutorial papers presented at the 41st International Conference on Application and Theory of Petri Nets and Concurrency, Petri Nets 2020, and the 20th International Conference on Application of Concurrency to System Design, ACSD 2020. The papers cover a diverse range of topics including model checking and system verification, refinement and synthesis; foundational work on specific classes of Petri nets; and innovative applications of Petri nets and other models of concurrency. Application areas covered in this volume are: process mining, verification, formal semantics, distributed simulations, business processes, distributed systems, and net synthesis. Thus, this volume gives a good overview of ongoing research on concurrent systems and Petri nets.

The 15th volume of ToPNoC contains revised and extended versions of a selection of the best workshop and tutorial papers presented at the 40th International Conference on Application and Theory of Petri Nets and Concurrency, Petri Nets 2019, and the 19th International Conference on Application of Concurrency to System Design, ACSD 2019. The papers cover a diverse range of topics including model checking and system verification, refinement and synthesis; foundational work on specific classes of Petri nets; and innovative applications of Petri nets and other models of concurrency. Application areas covered in this volume are: process mining, verification, formal semantics, communication protocols, business processes, distributed systems, and net synthesis. Thus, this volume gives a good overview of ongoing research on concurrent systems and Petri nets.

The 14th volume of ToPNoC contains revised and extended versions of a selection of the best workshop and tutorial papers presented at the 39th International Conference on Application and Theory of Petri Nets and Concurrency, Petri Nets 2018, and the 18th International Conference on Application of Concurrency to System Design, ACSD 2018.The 10 papers cover a diverse range of topics including model checking and system verification, refinement, and synthesis; foundational work on specific classes of Petri nets; and innovative applications of Petri nets and other models of concurrency. Application areas covered in this volume are: process mining, verification, formal semantics, communication protocols, business processes, distributed systems, and net synthesis. Thus, this volume gives a good overview of ongoing research on concurrent systems and Petri nets.

The 13th volume of ToPNoC contains revised and extended versions of a selection of the best workshop papers presented at the 38th International Conference on Application and Theory of Petri Nets and Concurrency, Petri Nets 2017, and the 17th International Conference on Application of Concurrency to System Design, ACSD 2017. The 9 papers cover a diverse range of topics including model checking and system verification, refinement, and synthesis; foundational work on specific classes of Petri nets; and innovative applications of Petri nets and other models of concurrency. Application areas covered in this volume are: fault-tolerance, service composition, databases, communication protocols, business processes, and distributed systems. Thus, this volume gives a good overview of ongoing research on concurrent systems and Petri nets.

These Transactions publish archival papers in the broad area of Petri nets and other models of concurrency, ranging from theoretical work to tool support and industrial applications. ToPNoC issues are published as LNCS volumes, and hence are widely distributed and indexed. This Journal has its own Editorial Board which selects papers based on a rigorous two-stage refereeing process. ToPNoC contains: - Revised versions of a selection of the best papers from workshops and tutorials at the annual Petri net conferences- Special sections/issues within particular subareas (similar to those published in the Advances in Petri Nets series)- Other papers invited for publication in ToPNoC- Papers submitted directly to ToPNoC by their authors The 10th volume of ToPNoC contains revised and extended versions of a selection of the best workshop papers presented at the 35th International Conference on Application and Theory of Petri Nets and Concurrency, Petri Nets 2014, and the 14th International Conference on Application of Concurrency to System Design, ACSD 2014. It also contains one paper submitted directly to ToPNoC.The 8 papers cover a diverse range of topics including model checking and system verification, refinement, and synthesis; foundational work on specific classes of Petri nets; and innovative applications of Petri nets and other models of concurrency.