Machine Learning is the study of methods for programming computers to learn. Computers are applied to a wide range of tasks, and for most of these it is relatively easy for programmers to design and implement the necessary software. However, there are many tasks for which this is difficult or impossible. These can be divided into four general categories. First, there are problems for which there exist no human experts. For example, in modern automated manufacturing facilities, there is a need to predict machine failures before they occur by analyzing sensor readings. Because the machines are new, there are no human experts who can be interviewed by a programmer to provide the knowledge necessary to build a computer system. A machine learning system can study recorded data and subsequent machine failures and learn prediction rules. Second, there are problems where human experts exist, but where they are unable to explain their expertise. This is the case in many perceptual tasks, such as speech recognition, hand-writing recognition, and natural language understanding. Virtually all humans exhibit expert-level abilities on these tasks, but none of them can describe the detailed steps that they follow as they perform them. Fortunately, humans can provide machines with examples of the inputs and correct outputs for these tasks, so machine learning algorithms can learn to map the inputs to the outputs. Third, there are problems where phenomena are changing rapidly. In finance, for example, people would like to predict the future behavior of the stock market, of consumer purchases, or of exchange rates. These behaviors change frequently, so that even if a programmer could construct a good predictive computer program, it would need to be rewritten frequently. A learning program can relieve the programmer of this burden by constantly modifying and tuning a set of learned prediction rules. Fourth, there are applications that need to be customized for each computer user separately. Consider, for example, a program to filter unwanted electronic mail messages. Different users will need different filters. It is unreasonable to expect each user to program his or her own rules, and it is infeasible to provide every user with a software engineer to keep the rules up-to-date. A machine learning system can learn which mail messages the user rejects and maintain the filtering rules automatically. Machine learning addresses many of the same research questions as the fields of statistics, data mining, and psychology, but with differences of emphasis. Statistics focuses on understanding the phenomena that have generated the data, often with the goal of testing different hypotheses about those phenomena. Data mining seeks to find patterns in the data that are understandable by people. Psychological studies of human learning aspire to understand the mechanisms underlying the various learning behaviors exhibited by people (concept learning, skill acquisition, strategy change, etc.).

Machine learning

ing WS1S Systems to Verify Parameterized Networks . . . . . . . . . . . . 188 Kai Baukus, Saddek Bensalem, Yassine Lakhnech and Karsten Stahl FMona: A Tool for Expressing Validation Techniques over Infinite State Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204 J.-P. Bodeveix and M. Filali Transitive Closures of Regular Relations for Verifying Infinite-State Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220 Bengt Jonsson and Marcus Nilsson Diagnostic and Test Generation Using Static Analysis to Improve Automatic Test Generation . . . . . . . . . . . . . 235 Marius Bozga, Jean-Claude Fernandez and Lucian Ghirvu Efficient Diagnostic Generation for Boolean Equation Systems . . . . . . . . . . . . 251 Radu Mateescu Efficient Model-Checking Compositional State Space Generation with Partial Order Reductions for Asynchronous Communicating Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 266 Jean-Pierre Krimm and Laurent Mounier Checking for CFFD-Preorder with Tester Processes . . . . . . . . . . . . . . . . . . . . . . . 283 Juhana Helovuo and Antti Valmari Fair Bisimulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 299 Thomas A. Henzinger and Sriram K. Rajamani Integrating Low Level Symmetries into Reachability Analysis . . . . . . . . . . . . . 315 Karsten Schmidt Model-Checking Tools Model Checking Support for the ASM High-Level Language . . . . . . . . . . . . . . 331 Giuseppe Del Castillo and Kirsten Winter Table of

Tools and Algorithms for the Construction and Analysis of Systems. Proc. TACAS 2009

Technical report series

Handbook of logic in computer science.

The π-Calculus: A theory of mobile processes by Davide Sangiorgi and David Walker Formal methods have formed the foundation of Computer Science since its inception. Although, initially these formal methods dealt with processes and systems on an individual basis, the paradigm has shifted with the dawn of the age of computer networks. When dealing with systems with interconnected, communicating, dependent, cooperative, and competitive components, the older outlook of analyzing and developing singular systems—and the tools that went with it—were hardly suitable. This led to the development of theories and tools that would support the new paradigm. On the tools end, the development has been widespread and satisfactory: programming languages, development frameworks, databases, and even end-user software products such as word processors, have gained network-awareness. However on the theoretical end, the development has been far less satisfactory. The major work was done by Robin Milner, Joachim Parrow, and David Walker who developed the formalism known as π-calculus in 1989. π-calculus is a process calculus that treats communication between its components as the basic form of computation. It has been quite successful as a foundation of several other calculi in the field and as Milner puts it, it has become common to express ideas about interactions and mobility in variants of the calculus. Introduction The current book serves as a comprehensive reference to π-calculus. Besides Milner's own book on the subject, this is the only other book-length publication on the topic. In many ways, it is much more comprehensive than Milner's: a much wider area of topics are dealt with and in more detail as well. Contents The book is split into seven part. The first part presents the basic theory of π-calculus. However, basic does not mean concise: every topic is discussed in great detail. The section on bisimulation is particularly intensive and provides several insights about the motivation for the theory. Part two discusses several variants of the original calculus. By varying several characteristics of the calculus, such as whether a process can communicate with more than processes at a time, we can obtain these variants. A number of interesting properties of the language are studied by the other when discussing these variants. As can be understood from the title, the calculus' contribution to analyzing mobile processes is a major topic, and it is dealt with extensively starting from part three. The basics are introduced by the way of a sophisticated typing system whose application in speciying complex processes is presented in part four. Part five looks at higher-order π-calculus in which composed systems are considered as first-class citizens. Part six is one of the best in the book and discusses the relation between π-calculus and lambda-calculus, which is an older and more basic calculus. Finally part seven shows how π-calculus can be employed in studying practical, modern software engineering concepts such as object-oriented programming. Impressions One of my disappointments with this book is in how often the reader is left perplexed with some of the theoretical developments, specially in part three. π-calculus is a complicated topic, even for the graduate student audience to which this book is directed, and the author would have done much better by reducing the number of topics and instead focusing on more lucid and detailed explanations. There are several experimental digressions throughout the book, which although interesting, take away from some of the momentum of sequential study. For example, topics such as comparison and encoding of one language to another could be easily moved to a separate section in order to make the content more suitable for self-study. Another issue is the little effort towards making the connection from the theoretical to the practical. The main reason why formal methods have not been adopted in mainstream software development pracitces is that often it is unclear to developers how formalisms can contribute towards the software engineering process. The book would have served its purpose much better if it had spent part of eah chapter discussing the practical application of that chapter's content. For example, congruence checking and bisimulation can be incredbily exciting topics for programmers to learn if they can see practical applications of such powerful techniques. Beyond the above criticism, the book is absolutely indispensible to students and researchers in the field of formal methods. Currently it serves as the primary reference for anyone who wishes to learn the various aspects of π-calculus in detail. Raheel Ahmad

The Ï-Calculus: A theory of mobile processes

We look at modelling of a choice between several ‘bursts’ of concurrent actions in a Petri net. If ‘silent’ transitions are disallowed, a construction based on Cartesian product is traditionally used, resulting in an exponential explosion in the model size. We demonstrate that this exponential explosion can be avoided. We show the equivalence between this modelling problem and the problem of finding an edge clique cover of a complete multipartite graph, which gives major insights into the former problem as well as linking it to the existing results from graph theory. It turns out that the exponential number of places created by the Cartesian product construction can be improved down to polynomial (quadratic) in the worst case, and down to logarithmic in the best (non-degraded) case. For example, to express a choice between 10 pairs of concurrent transitions, the Cartesian product construction creates 1024 places, even though 6 places are sufficient. We also derive several lower and upper bounds on the numbers of places and arcs. As these results affect the ‘core’ modelling techniques based on Petri nets, eliminating a source of an exponential explosion, we hope they will have applications in Petri net modelling and translations of various formalisms to Petri nets. As an example, applying them to translate Burst Automata to Petri nets reduces the size of the resulting Petri net from exponential down to polynomial. 

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Avoiding Exponential Explosion in Petri Net Models of Control Flows

This paper presents SONCraft - an open source tool for editing, simulating, and analysing Structured Occurrence Nets (SONs), which is a Petri net-based formalism for modelling the behaviour of complex evolving systems. The tool is implemented as a Java plug-in within the Workcraft platform, which is a flexible framework for the development and analysis of Interpreted Graph Models. SONCraft provides an easy to use graphical interface that facilitates model entry, supports interactive visual simulation, and allows the use of a set of analytical tools. We give an overview of SONCraft functionality and architecture.

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SONCraft: A Tool for Construction, Simulation, and Analysis of Structured Occurrence Nets

Invited Papers.- Kronecker Algebra and (Stochastic) Petri Nets: Is It Worth the Effort?.- The Flux of Interaction.- Towards a Notion of Distributed Time for Petri Nets.- Full Papers.- Identifying Commonalities and Differences in Object Life Cycles Using Behavioral Inheritance.- Timed Petri Nets and BQOs.- CPN/Tools: A Post-WIMP Interface for Editing and Simulating Coloured Petri Nets.- Petri Net Based Design and Implementation Methodology for Discrete Event Control Systems.- Condensed State Spaces for Timed Petri Nets.- Unfolding of Products of Symmetrical Petri Nets.- partial Order Verification of Programmable Logic Controllers.- Structural Characterization and Qualitative Properties of Product Form Stochastic Petri Nets.- Generalized Conditions for Liveness Enforcement and Deadlock Prevention in Petri Nets.- A Concurrent Semantics of Static Exceptions in a Parallel Programming Language.- A Concurrent Semantics of Static Exceptions in a Parallel Programming Language.- Modelling the Structure and Behaviour of Petri Net Agents.- Modelling the Structure and Behaviour of Petri Net Agents.- Model Checking LTL Properties of High-Level Petri Nets with Fairness Constraints.- Model Checking LTL Properties of High-Level Petri Nets with Fairness Constraints.- Incremental State Space Construction for Coloured Petri Nets.- Incremental State Space Construction for Coloured Petri Nets.- Optimising Enabling Tests and Unfoldings of Algebraic System Nets.- Optimising Enabling Tests and Unfoldings of Algebraic System Nets.- Extending the Petri Box Calculus with Time.- Extending the Petri Box Calculus with Time.- Abstractions and Partial Order Reductions for Checking Branching Properties of Time Petri Nets.- Abstractions and Partial Order Reductions for Checking Branching Properties of Time Petri Nets.- Pr/T-Net Based Seamless Design of Embedded Real-Time Systems.- Pr/T-Net Based Seamless Design of Embedded Real-Time Systems.- Rewriting Logic and Elan: Prototyping Tools for Petri Nets with Time.- Rewriting Logic and Elan: Prototyping Tools for Petri Nets with Time.- Partial S-Invariants for the Verification of Infinite Systems Families.- Partial S-Invariants for the Verification of Infinite Systems Families.

Applications and theory of Petri nets 2001 : 22nd International Conference, ICATPN 2001, Newcastle upon Tyne, UK, June 25-29, 2001 : proceedings

Automated synthesis from behavioural specifications is an attractive and powerful way of constructing concurrent systems. Here we focus on the problem of synthesising a membrane system from a behavioural specification given in the form of a transition system which specifies the desired state space of the system to be constructed. We demonstrate how a Petri net solution to this problem, based on the notion of region of a transition system, yields a method of automated synthesis of membrane systems from state spaces.

Membrane Systems and Petri Net Synthesis

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Maciej Koutny

Papers

Avoiding Exponential Explosion in Petri Net Models of Control Flows

SONCraft: A Tool for Construction, Simulation, and Analysis of Structured Occurrence Nets

Applications and theory of Petri nets 2001 : 22nd International Conference, ICATPN 2001, Newcastle upon Tyne, UK, June 25-29, 2001 : proceedings

Membrane Systems and Petri Net Synthesis

Steps and Coverability in Inhibitor Nets