Monographs in Theoretical Computer Science. An EATCS Series – serie

In this book the author explains domain engineering and the underlying science, and he then shows how we can derive requirements prescriptions for computing systems from domain descriptions. A further motivation is to present domain descriptions, requirements prescriptions, and software design specifications as mathematical quantities.The author's maxim is that before software can be designed we must understand its requirements, and before requirements can be prescribed we must analyse and describe the domain for which the software is intended. He does this by focusing on what it takes to analyse and describe domains. By a domain we understand a rationally describable discrete dynamics segment of human activity, of natural and man-made artefacts, examples include road, rail and air transport, container terminal ports, manufacturing, trade, healthcare, and urban planning. The book addresses issues of seemingly large systems, not small algorithms, and it emphasizes descriptionsas formal, mathematical quantities.This is the first thorough monograph treatment of the new software engineering phase of software development, one that precedes requirements engineering. It emphasizes a methodological approach by treating, in depth, analysis and description principles, techniques and tools. It does this by basing its domain modeling on fundamental philosophical principles, a view that is new for a computer science monograph.The book will be of value to computer scientists engaged with formal specifications of software. The author reveals this as a field of interesting problems, most chapters include pointers to further study and exercises drawn from practical engineering and science challenges. The text is supported by a primer to the formal specification language RSL and extensive indexes.

In this book the author explains domain engineering and the underlying science, and he then shows how we can derive requirements prescriptions for computing systems from domain descriptions. A further motivation is to present domain descriptions, requirements prescriptions, and software design specifications as mathematical quantities.The author's maxim is that before software can be designed we must understand its requirements, and before requirements can be prescribed we must analyse and describe the domain for which the software is intended. He does this by focusing on what it takes to analyse and describe domains. By a domain we understand a rationally describable discrete dynamics segment of human activity, of natural and man-made artefacts, examples include road, rail and air transport, container terminal ports, manufacturing, trade, healthcare, and urban planning. The book addresses issues of seemingly large systems, not small algorithms, and it emphasizes descriptionsas formal, mathematical quantities.This is the first thorough monograph treatment of the new software engineering phase of software development, one that precedes requirements engineering. It emphasizes a methodological approach by treating, in depth, analysis and description principles, techniques and tools. It does this by basing its domain modeling on fundamental philosophical principles, a view that is new for a computer science monograph.The book will be of value to computer scientists engaged with formal specifications of software. The author reveals this as a field of interesting problems, most chapters include pointers to further study and exercises drawn from practical engineering and science challenges. The text is supported by a primer to the formal specification language RSL and extensive indexes.

​Congestion games are a fundamental class of games widely considered and studied in non-cooperative game theory, introduced to model several realistic scenarios in which people share a limited quantity of goods or services. In congestion games there are several selfish players competing for a set of resources, and each resource incurs a certain latency, expressed by a congestion-dependent function, to the players using it. Each player has a certain weight and an available set of strategies, where each strategy is a non-empty subset of resources, and aims at choosing a strategy minimizing her personal cost, which is defined as the sum of the latencies experienced on all the selected resources. The impact of selfish behavior in congestion games generally deteriorates the social welfare, thus reducing their performance. This deterioration is generally estimated by the price of anarchy, a metric that compares the worst Nash equilibrium configuration with the optimal social welfare, so that the larger the price of anarchy for a game, the higher the impact of selfish behavior. The book derives from the first author's thesis, which won the Best Italian PhD Thesis in Theoretical Computer Science in 2019, awarded by the Italian chapter of the EATCS. The book will be revised for broader audience, and the thesis supervisor is joining as coauthor following the suggestion of the series. The authors will introduce examples for initial definitions with detailed explanations, and expand the scope to the broader results in the area rather than their specific work.

​Congestion games are a fundamental class of games widely considered and studied in non-cooperative game theory, introduced to model several realistic scenarios in which people share a limited quantity of goods or services. In congestion games there are several selfish players competing for a set of resources, and each resource incurs a certain latency, expressed by a congestion-dependent function, to the players using it. Each player has a certain weight and an available set of strategies, where each strategy is a non-empty subset of resources, and aims at choosing a strategy minimizing her personal cost, which is defined as the sum of the latencies experienced on all the selected resources. The impact of selfish behavior in congestion games generally deteriorates the social welfare, thus reducing their performance. This deterioration is generally estimated by the price of anarchy, a metric that compares the worst Nash equilibrium configuration with the optimal social welfare, so that the larger the price of anarchy for a game, the higher the impact of selfish behavior. The book derives from the first author's thesis, which won the Best Italian PhD Thesis in Theoretical Computer Science in 2019, awarded by the Italian chapter of the EATCS. The book will be revised for broader audience, and the thesis supervisor is joining as coauthor following the suggestion of the series. The authors will introduce examples for initial definitions with detailed explanations, and expand the scope to the broader results in the area rather than their specific work.

This is the first comprehensive introduction to the theory of word-representable graphs, a generalization of several classical classes of graphs, and a new topic in discrete mathematics.After extensive introductory chapters that explain the context and consolidate the state of the art in this field, including a chapter on hereditary classes of graphs, the authors suggest a variety of problems and directions for further research, and they discuss interrelations of words and graphs in the literature by means other than word-representability.The book is self-contained, and is suitable for both reference and learning, with many chapters containing exercises and solutions to seleced problems. It will be valuable for researchers and graduate and advanced undergraduate students in discrete mathematics and theoretical computer science, in particular those engaged with graph theory and combinatorics, and also for specialists in algebra.

This is the first comprehensive introduction to the theory of word-representable graphs, a generalization of several classical classes of graphs, and a new topic in discrete mathematics.After extensive introductory chapters that explain the context and consolidate the state of the art in this field, including a chapter on hereditary classes of graphs, the authors suggest a variety of problems and directions for further research, and they discuss interrelations of words and graphs in the literature by means other than word-representability.The book is self-contained, and is suitable for both reference and learning, with many chapters containing exercises and solutions to seleced problems. It will be valuable for researchers and graduate and advanced undergraduate students in discrete mathematics and theoretical computer science, in particular those engaged with graph theory and combinatorics, and also for specialists in algebra.

This book deals with the problem of finding suitable languages that can represent specific classes of Petri nets, the most studied and widely accepted model for distributed systems. Hence, the contribution of this book amounts to the alphabetization of some classes of distributed systems. The book also suggests the need for a generalization of Turing computability theory.It is important for graduate students and researchers engaged with the concurrent semantics of distributed communicating systems. The author assumes some prior knowledge of formal languages and theoretical computer science.

This book deals with the problem of finding suitable languages that can represent specific classes of Petri nets, the most studied and widely accepted model for distributed systems. Hence, the contribution of this book amounts to the alphabetization of some classes of distributed systems. The book also suggests the need for a generalization of Turing computability theory.It is important for graduate students and researchers engaged with the concurrent semantics of distributed communicating systems. The author assumes some prior knowledge of formal languages and theoretical computer science.

Replacement systems, such as term rewriting systems, tree manipulat­ ing systems, and graph grammars, have been used in Computer Science in the context of theorem proving, program optimization, abstract data types, algebraic simplification, and symbolic comput­ ation. Replacement systems for strings arose about seventy years earlier in the area of combinatory logic and group theory. The most natural and appropriate formalism for dealing with string rewriting is the notion of a semi-Thue system and this monograph treats its central aspects. The reduction relation is here defined firstly by the direction of the rules and secondly by some metric that yields efficient algorithms. These systems are general enough to discuss the basic notions of arbitrary replacement systems, such as termination, confluence, and the Church-Rosser property in its original meaning. Confluent semi-Thue systems in which each and every derivation consists of finitely many steps only are called complete; they guarantee the existence of unique normal forms as canonical representatives of the Thue congruence classes. Each such system can be considered a nondeterministic algorithm for the word problem which works correctly without backtracking. This is often conceptually simpler and more elegant than an ad hoc construction. In many cases a replace­ ment system can be altered to a complete system by the Knuth-Bendix completion method.

The theory of parsing is an important application area of the theory of formal languages and automata. The evolution of modem high-level programming languages created a need for a general and theoretically dean methodology for writing compilers for these languages. It was perceived that the compilation process had to be "syntax-directed", that is, the functioning of a programming language compiler had to be defined completely by the underlying formal syntax of the language. A program text to be compiled is "parsed" according to the syntax of the language, and the object code for the program is generated according to the semantics attached to the parsed syntactic entities. Context-free grammars were soon found to be the most convenient formalism for describing the syntax of programming languages, and accordingly methods for parsing context-free languages were devel­ oped. Practical considerations led to the definition of various kinds of restricted context-free grammars that are parsable by means of efficient deterministic linear-time algorithms.

Computational geometry as an area of research in its own right emerged in the early seventies of this century. Right from the beginning, it was obvious that strong connections of various kinds exist to questions studied in the considerably older field of combinatorial geometry. For example, the combinatorial structure of a geometric problem usually decides which algorithmic method solves the problem most efficiently. Furthermore, the analysis of an algorithm often requires a great deal of combinatorial knowledge. As it turns out, however, the connection between the two research areas commonly referred to as computa­ tional geometry and combinatorial geometry is not as lop-sided as it appears. Indeed, the interest in computational issues in geometry gives a new and con­ structive direction to the combinatorial study of geometry. It is the intention of this book to demonstrate that computational and com­ binatorial investigations in geometry are doomed to profit from each other. To reach this goal, I designed this book to consist of three parts, acorn binatorial part, a computational part, and one that presents applications of the results of the first two parts. The choice of the topics covered in this book was guided by my attempt to describe the most fundamental algorithms in computational geometry that have an interesting combinatorial structure. In this early stage geometric transforms played an important role as they reveal connections between seemingly unrelated problems and thus help to structure the field.

Graphs are widely used to represent structural information in the form of objects and connections between them. Graph transformation is the rule-based manipulation of graphs, an increasingly important concept in computer science and related fields. This is the first textbook treatment of the algebraic approach to graph transformation, based on algebraic structures and category theory.Part I is an introduction to the classical case of graph and typed graph transformation. In Part II basic and advanced results are first shown for an abstract form of replacement systems, so-called adhesive high-level replacement systems based on category theory, and are then instantiated to several forms of graph and Petri net transformation systems. Part III develops typed attributed graph transformation, a technique of key relevance in the modeling of visual languages and in model transformation. Part IV contains a practical case study on model transformation and a presentation of the AGG (attributed graph grammar) tool environment. Finally the appendix covers the basics of category theory, signatures and algebras.The book addresses both research scientists and graduate students in computer science, mathematics and engineering.

Local search has been applied successfully to a diverse collection of optimization problems. It's appreciated for its basic conceptual foundation, its general applicability, and its power to serve as a source for new search paradigms. The typical characteristics of combinatorial optimization problems to which local search can be applied, its relation to complexity theory, and the combination with randomized search features have led to a wealth of interesting theoretical results. However, these results are scattered throughout the literature. This is the first book that presents a large collection of theoretical results in a consistent manner, thus providing the reader with a coherent overview of the achievements obtained so far, but also serving as a source of inspiration for the development of novel results in the challenging field of local search.

In a model-based development of software systems different views on a system are elaborated using appropriate modeling languages and techniques. Because of the unavoidable heterogeneity of the viewpoint models, a semantic integration is required, to establish the correspondences of the models and allow checking of their relative consistency.The integration approach introduced in this book is based on a common semantic domain of abstract systems, their composition and development. Its applicability is shown through semantic interpretations and compositional comparisons of different specification approaches. These range from formal specification techniques like process calculi, Petri nets and rule-based formalisms to semiformal software modeling languages like those in the UML family.

Duration calculus constitutes a formal approach to the development of real-time systems; as an interval logic with special features for expressing and analyzing time durations of states in real-time systems, it allows for representing and formally reasoning about requirements and designs at an appropriate level of abstraction.This book presents the logical foundations of duration calculus in a coherent and thorough manner. Through selective case studies it explains how duration calculus can be applied to the formal specification and verification of real-time systems. The book also contains an extensive survey of the current research in this field.The material included in this book has been used for graduate and postgraduate courses, while it is also suitable for experienced researchers and professionals.

The construction of any broadly understood theory of information or infor­ mation processing system involves two major methodological processes: (1) abstraction and analysis, (2) reasoning and computing. This monograph is a realisation of these two processes in relation to the study of incompleteness of information. The paradigm we are working with is inspired by a rough-set approach to data analysis: the formalisms we develop enable the use of a non­ invasive data representation. This means that the only information which is and must be used in the process of analysis is the actual information that is to be analysed; we do not require any additional sources of information. An abstraction is formed in the process of conception, design, and develop­ ment of structures. Then analysis leads to a selection of a class of structures. In this book we delineate a class of informational structures that enable us to represent both numerical and non-numerical information and we analyse var­ ious manifestations of its incompleteness. We discuss several general types of incompleteness of information which are grounded in a rough-set-style view of imprecision and uncertainty. Manifestations of these types of incompleteness in information systems are investigated.

An Invitation to the Dance It is an underappreciated fact that sets may have various types of complex­ ity, and not all types are in harmony with each other. The primary goal of this book is to unify and make more widely accessible a vibrant stream of research-the theory of semi-feasible computation-that perfectly showcases the richness of, and contrasts between, the central types of complexity. The semi-feasible sets, which are most commonly referred to as the P­ selective sets, are those sets L for which there is a deterministic polynornial­ time algorithm that, when given as input any two strings of which at least one belongs to L, will output one of them that is in L. The reason we saythat the semi-feasible sets showcase the contrasts among types of complexity is that it is well-known that many semi-feasible sets have no recursive algorithms (thus their time complexitycannot be upper-bounded by standard time-complexity classes), yet all semi-feasible sets are simple in a wide range of other natural senses. In particular, the semi-feasible sets have small circuits, they are in the extended low hierarchy, and they cannot be NP-complete unless P = NP. The semi-feasible sets are fascinating for many reasons. First, as men­ tioned above, they showcase the fact that mere deterministic time complex­ ity is not the only potential type of complexity in the world of computation.

This book is concerned with a number of theories that can be used for describ­ ing and analyzing systems of interacting components in case it is desirable or necessary to regard their time-dependent behavior. Society is becoming increasingly more dependent on complex computer­ based systems that are composed of several components that act concurrently and interact - to synchronize and communicate with each other. The com­ plexity of these systems arises to a great extent from the many ways in which their components can interact. The need that these components act and in­ teract on time as well adds considerably to the complexity. In developing such a system, it is important to be able to acquire a better understanding of the relevant issues at the conceptual level, to describe the system in a precise way at various levels of detail, and to analyze it on the basis of the descriptions. When the early algebraic theories about processes, such as ACP [16, 17, 20], CCS [49, 50] and CSP [27, 39], were developed for that purpose, the established opinion was still that timing is a concern that can more often than not be treated independently. It is therefore not surprising that timing is deliberately ignored in those theories. They have now all been extended to deal with timing.

The OrIgIn of this monograph is a course entitled "Semantics­ directed Compiler Generation" which Professor Neil D. Jones gave in 1982 at Copenhagen University, where I was a student at the time. In this course, he described a compiler generator, called CERES, which he was developing. I immediately felt attracted to the unusual combination of mathematical reasoning about com­ pilers and the small intricate building blocks that made up the running system. As I came to understand the system I discovered that within the existing mathematical framework one could express compiler generation as a special case of compilation; this led to a specification of a compiler generator which was bootstrapped on itself resulting in a machine-generated compiler generator. The purpose of this monograph is to describe the CERES system we produced in 1983-84 and compare it with other systems, includ­ ing more recent ones. Also, it is as relevant today as it was then to discuss the role of compiler generators as an aid in the design and implementation of programming languages; this I do in Chap. 5. This monograph is a strongly revised version of the cando scient.

This work is Volume II of a two-volume monograph on the theory of deterministic parsing of context-free grammars. Volume I, "Languages and Parsing" (Chapters 1 to 5), was an introduction to the basic concepts of formal language theory and context-free parsing. Volume II (Chapters 6 to 10) contains a thorough treat­ ment of the theory of the two most important deterministic parsing methods: LR(k) and LL(k) parsing. Volume II is a continuation of Volume I; together these two volumes form an integrated work, with chapters, theorems, lemmas, etc. numbered consecutively. Volume II begins with Chapter 6 in which the classical con­ structions pertaining to LR(k) parsing are presented. These include the canonical LR(k) parser, and its reduced variants such as the LALR(k) parser and the SLR(k) parser. The grammarclasses for which these parsers are deterministic are called LR(k) grammars, LALR(k) grammars and SLR(k) grammars; properties of these grammars are also investigated in Chapter 6. A great deal of attention is paid to the rigorous development of the theory: detailed mathematical proofs are provided for most of the results presented.

Two important new concepts, module specifications and constraints, are introduced in this second volume of a three-volume set on fundamentals of algebraic specification. These concepts are motivated by problems in practical software development and are studied here from a theoretical point of view. Modularization is one of the main structuring principles in software development. Modules and module specifications can be seen as the basic building blocks which are used in modularization of software systems and software system specification. Constraints are introduced to increase the expressive power of algebraic specifications in order to make them more useful for practical applications. The book is suitable both as a textbook for graduate courses in formal specification of data types and software systems and as a reference for researchers and system developers.

This book proposes a purely classical first-order logical approach to the theory of programming. The authors, leading members of the famous "Hungarian school", use this approach to give a unified and systematic presentation of the theory. This approach provides formal methods and tools for reasoning about computer programs and programming languages by allowing the syntactic and semantic characterization of programs, the description of program properties, and ways to check whether a given program satisfies certain properties. The basic methods are logical extension, inductive definition and their combination, all of which admit an appropriate first-order representation of data and time. The framework proposed by the authors allows the investigation and development of different programming theories and logics from a unified point of view. Dynamic and temporal logics, for example, are investigated and compared with respect to their expressive and proof-theoretic powers. The book should appeal to both theoretical researchers and students.For researchers in computer science the book provides a coherent presentation of a new approach which permits the solution of various problems in programming theory in a unified manner by the use of first-order logical tools. The book may serve as a basis for graduate courses in programming theory and logic as it covers all important questions arising between the theory of computation and formal descriptive languages and presents an appropriate derivation system.

This three-volume work presents a coherent description of the theoretical and practical aspects of coloured Petri nets (CP-nets). The second volume contains a detailed presentation of the analysis methods for CP-nets. They allow the modeller to investigate dynamic properties of CP-nets.The main ideas behind the analysis methods are described as well as the mathematics on which they are based and also how the methods are supported by computer tools. Some parts of the volume are theoretical while others are application oriented. The purpose of the volume is to teach the reader how to use the formal analysis methods, which does not require a deep understanding of the underlying mathematical theory.

This book presents a coherent description of the theoretical and practical aspects of Coloured Petri Nets (CP-nets or CPN). It shows how CP-nets have been de­ veloped - from being a promising theoretical model to being a full-fledged lan­ guage for the design, specification, simulation, validation and implementation of large software systems (and other systems in which human beings and/or com­ puters communicate by means of some more or less formal rules). The book contains the formal definition of CP-nets and the mathematical theory behind their analysis methods. However, it has been the intention to write the book in such a way that it also becomes attractive to readers who are more interested in applications than the underlying mathematics. This means that a large part of the book is written in a style which is closer to an engineering textbook (or a users' manual) than it is to a typical textbook in theoretical computer science. The book consists of three separate volumes. The first volume defines the net model (i. e. , hierarchical CP-nets) and the basic concepts (e. g. , the different behavioural properties such as deadlocks, fair­ ness and home markings). It gives a detailed presentation of many small exam­ ples and a brief overview of some industrial applications. It introduces the for­ mal analysis methods. Finally, it contains a description of a set of CPN tools which support the practical use of CP-nets.

Restricted-orientation convexity is the study of geometric objects whose intersections with lines from some fixed set are connected. This notion generalizes standard convexity and several types of nontraditional convexity. We explore the properties of this generalized convexity in multidimensional Euclidean space, describes restricted-orientation analogs of lines, hyperplanes, flats, and halfspaces, and identify major properties of standard convex sets that also hold for restricted-orientation convexity. We then introduce the notion of strong restricted-orientation convexity, which is an alternative generalization of convexity, and show that its properties are also similar to those of standard convexity.

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.

Time-dependent scheduling involves problems in which the processing times of jobs depend on when those jobs are started. This book is a comprehensive study of complexity results and optimal and suboptimal algorithms concerning time-dependent scheduling in single-, parallel- and dedicated-machine environments. In addition to complexity issues and exact or heuristic algorithms which are typically presented in scheduling books, the author also includes more advanced topics such as matrix methods in time-dependent scheduling, and time-dependent scheduling with two criteria.The reader should be familiar with basic notions of calculus, discrete mathematics and combinatorial optimization theory, while the book offers introductory material on NP-complete problems, and the basics of scheduling theory. The author includes numerous examples, figures and tables, he presents different classes of algorithms using pseudocode, and he completes the book with an extensive bibliography, and author, symbol and subject indexes.The book is suitable for researchers working on scheduling, problem complexity, optimization, heuristics and local search algorithms.

By a specification language we understand a formal system of syntax, semantics and proof rules. The syntax and semantics define a language; the proof rules define a proof system. Specifications are expressions in the language, and reasoning over properties of these specifications is done within the proof system. This book presents comprehensive studies on nine specification languages and their logics of reasoning.The editors and authors are authorities on these specification languages and their application. Dedicated chapters address: the use of ASM (Abstract State Machines) in the classroom; the Event-B modelling method; a methodological guide to CafeOBJ logic; CASL, the Common Algebraic Specification Language; the Duration Calculus; the logic of the RAISE specification language (RSL); the specification language TLA+; the typed logic of partial functions and the Vienna Development Method (VDM); and Z logic and its applications. Each chapter is self-contained, with references, and symbol and concept indexes. Finally, in a unique feature, the book closes with short commentaries on the specification languages written by researchers closely associated with their original development.With extensive references and pointers to future developments, this book will be of interest to researchers and graduate students engaged with formal specification languages.

Model checking is a prominent technique used in the hardware and software industries for automatic verification. While it is very successful in finding subtle bugs in distributed systems, it faces the state explosion problem - the number of reachable states grows exponentially in the number of concurrent components. In this book the authors introduce unfoldings, an approach to model checking which alleviates the state explosion problem by means of concurrency theory. They offer a gentle introduction to the basics of the method, and in particular they detail an unfolding-based algorithm for model checking concurrent systems against properties specified as formulas of linear temporal logic (LTL). Self-contained chapters cover transition systems and their products; unfolding products; search procedures for basic verification problems, such as reachability and livelocks; and model checking LTL. The final chapter summarizes the results of the book, and points the reader to tools and case studies.The book will be of value to researchers and graduate students engaged in automatic verification and concurrency theory.