Showing papers on "Formal language published in 1997"

Handbook of Formal Languages

Abstract: The theory of formal languages is the oldest and most fundamental area of theoretical computer science. It has served as a basis of formal modeling from the early stages of programming languages to the recent beginnings of DNA computing. This first handbook of formal languages gives a comprehensive up-to-date coverage of all important aspects and subareas of the field. Best specialists of various subareas, altogether 50 in number, are among the authors. The maturity of the field makes it possible to include a historical perspective in many presentations. The individual chapters can be studied independently, both as a text and as a source of reference. The Handbook is an invaluable aid for advanced students and specialists in theoretical computer science and related areas in mathematics, linguistics, and biology.

Languages, automata, and logic

Abstract: The subject of this chapter is the study of formal languages (mostly languages recognizable by finite automata) in the framework of mathematical logic.

Two-dimensional languages

Abstract: The aim of this chapter is to generalize concepts and techniques of formal language theory to two dimensions. Informally, a two-dimensional string is called a picture and is defined as a rectangular array of symbols taken from a finite alphabet. A two-dimensional language (or picture language) is a set of pictures.

Formal verification of probabilistic systems

Abstract: This dissertation presents methods for the formal modeling and specification of probabilistic systems, and algorithms for the automated verification of these systems. Our system models describe the behavior of a system in terms of probability, nondeterminism, fairness and time. The formal specification languages we consider are based on extensions of branching-time temporal logics, and enable the expression of single-event and long-run average system properties. This latter class of properties, not expressible with previous formal languages, includes most of the performance properties studied in the field of performance evaluation, such as system throughput and average response time. Our choice of system models and specification languages has been guided by the goal of providing efficient verification algorithms. The algorithms rely on the theory of Markov decision processes, and exploit a connection between the graph-theoretical and probabilistic properties of these processes. This connection also leads to new results about classical problems, such as an extension to the solvable cases of the stochastic shortest path problem, an improved algorithm for the computation of reachability probabilities, and new results on the average reward problem for semi-Markov decision processes.

Towards a mathematical operational semantics

Abstract: We present a categorical theory of 'well-behaved' operational semantics which aims at complementing the established theory of domains and denotational semantics to form a coherent whole. It is shown that, if the operational rules of a programming language can be modelled as a natural transformation of a suitable general form, depending on functorial notions of syntax and behaviour, then one gets the following for free: an operational model satisfying the rules and a canonical, internally fully abstract denotational model which satisfies the operational rules. The theory is based on distributive laws and bialgebras; it specialises to the known classes of well-behaved rules for structural operational semantics, such as GSOS.

Combinatorics of words

Abstract: This is a survey on combinatorics of words to appear as a chapter in Handbook of Formal Languages. The topics covered in details are: defect effect, equations as properties of words, periodicity, finiteness conditions, avoidabilty and subword complexity.

Foundations of Computing

Abstract: Provides an introduction to the theory of computing science. Covering the main areas of complexity theory, automata and formal languages in a coherent way, the text also covers the theoretical aspects of more applied areas. The author's approach is to stimulate students' understanding of the relevance of theory to important application areas - for example, image processing, communication networks and cryptography are all discussed. The book also provides numerous examples, graded exercises and diagrams.

Semirings and formal power series: their relevance to formal languages and automata

Abstract: The purpose of Chapter 9 is to develop some classical results on formal languages and automata by an algebraic treatment using semirings, formal power series and matrices. The use of semirings, formal power series and matrices makes the proofs computational in nature and, consequently, more satisfactory from the mathematical point of view than the customary proofs.

Full abstraction for functional languages with control

Abstract: This paper considers the consequences of relaxing the bracketing condition on 'dialogue games', showing that this leads to a category of games which can be 'factorized' into a well-bracketed substructure, and a set of classically typed morphisms. These are shown to be sound denotations for control operators, allowing the factorization to be used to extend the definability result for PCF to one for PCF with control operators at atomic types. Thus we define a fully abstract and effectively presentable model of a functional language with non-local control as part of a modular approach to modelling non-functional features using games.

Mathematical Linguistics and Proof Theory

Abstract: Publisher Summary In the traditional sense of the term, “mathematical linguistics” is a branch of applied algebra mainly concerned with formal languages, formal grammars, and automata—the latter being purely computational devices that generate formal languages. A natural link between proof theory and semantics has been established by the constructive approaches in logic as the so–called “formulas-as-types” interpretation: typed lambda terms can be interpreted as formal proofs in natural deduction systems. This chapter discusses certain most characteristic links between proof theory and formal grammars. It aims to persuade the reader of the generic unity of proof structures in appropriate deductive systems and syntactic and semantic structures generated by corresponding grammars. The chapter discusses some algebra connected with syntactic structures determined by proofs in the deductive part of grammars. The algebraic models of deductive systems underlying grammars are considered in the chapter. The algebraic models of logical systems are a traditional domain of metalogic. Substructural logics relevant to the theory of grammar give rise to special algebraic structures residuated algebras.

Digital images and formal languages

Abstract: We discuss the application of (weighted) finite automata to image specification and image-data compression and applications of (weighted) finite transducers to image manipulation.

Abstract syntax from concrete syntax

Abstract: Syntax from Concrete Syntax

New Trends in Formal Languages

Abstract: The first € price and the £ and $ price are net prices, subject to local VAT. Prices indicated with * include VAT for books; the €(D) includes 7% for Germany, the €(A) includes 10% for Austria. Prices indicated with ** include VAT for electronic products; 19% for Germany, 20% for Austria. All prices exclusive of carriage charges. Prices and other details are subject to change without notice. All errors and omissions excepted. G. Paun, A. Salomaa (Eds.) New Trends in Formal Languages

Models of Computation and Formal Languages

Abstract: Preface Chapter 0 - Mathematical Preliminaries Part I: Models of Computation Chapter 1 - Turning Machines Chapter 2 - Additional Varieties of Turning Machines Chapter 3 - An Introduction to Recursion Theory Chapter 4 - Markov Algorithms Chapter 5 - Register Machines Chapter 6 - Post Systems (Optional) Chapter 7 - The Vector Machine Model of Parallel Computation (Optional) Chapter 8 - The Bounds of Computability Part II: A Hierarchy of Automata and Formal Languages Chapter 9 - Regular Languages and Finite-State Automata Chapter 10 - Context-Free Languages and Pushdown-Stock Automata Chapter 11 - Context-Free Languages and Compiler Design Theory (Optional) Chapter 12 - Context-Sensitive Languages and Linear Bounded Automata Chapter 13 - Generative Grammars an the Chomsky Hierarchy Epilogue

An introduction to ET-LOTOS for the description of time-sensitive systems

Abstract: Enhanced Timed-LOTOS, called ET-LOTOS, is an extension of LOTOS allowing the modelling of time-sensitive system (ie systems whose behaviour is influenced by the passing of time) It is the basis of the timed extension of LOTOS currently developed by ISO (1995) The purpose of this paper is to present ET-LOTOS in a tutorial style and show its applicability The detailed study of the formal semantics is addressed in another paper A collection of small, but realistic, examples illustrates a wide variety of time-sensitive protocol mechanisms These examples are used to introduce and justify the extensions of our language Finally, the basics of the formal semantics are given and a comparison is made with other timed formalisms

Formal languages: an introduction and a synopsis

Abstract: What is a language? By consulting a dictionary one finds, among others, the following explanations: 1 The body of words and systems for their use common to people who are of the same community or nation, the same geographical area, or the same cultural tradition. 2 Any set or system of signs or symbols used in a more or less uniform fashion by a number of people who are thus enabled to communicate intelligibly with one other. 3 Any system of formalized symbols, signs, gestures, or the like, used or conceived as a means of communicating thought, emotion, etc.

Foundations of computer science : potential--theory--cognition

Abstract: The might of formulas and their limits.- Hardware - Software.- Defining discipline.- Computer science as cultural development.- Towards adjusting informatics education to information era.- Informatics and society: A curriculum for distance education.- Syntactic and semantic aspects of parallelism.- Unique fixpoints in complete lattices with applications to formal languages and semantics.- On abstract families of languages, power series, and elements.- Are there formal languages complete for SymSPACE(log n)?.- On twist-closed trios: A new morphic characterization of r.e. sets.- An automata approach to some problems on context-free grammars.- On aperiodic sets of Wang tiles.- Closure under complementation of logspace complexity classes - A survey -.- A relation between sparse and printable sets in NSPACE(log n).- A foundation for computable analysis.- A computer scientist's view of life, the universe, and everything.- Calendars and chronologies.- A uniform approach to Petri Nets.- Observing partial order runs of Petri Nets.- Representation theorems for Petri Nets.- A remark on trace equations.- Verification of distributed algorithms with algebraic Petri Nets.- A short story on action refinement.- Interactive and reactive systems: States, observations, experiments, input, output, nondeterminism, compositionality and all that.- Discrete time analysis of a state dependent tandem with different customer types.- How distributed algorithms play the token game.- The asynchronous stack revisited: Rounds set the twilight reeling.- Online scheduling of continuous media streams.- Contribution to Goodenough's and Gerhart's theory of software testing and verification: Relation between strong compiler test and compiler implementation verification.- On the arrangement complexity of uniform trees.- A relational-functional integration for declarative programming.- Inside and outside the Chinese room.- Abstract structures in spatial cognition.- Spatial and temporal structures in cognitive processes.- Qualitative vs. Fuzzy representations of spatial distance.- What's a part? On formalizing part-whole relations.- SPOCK: A feasibility study on the completeness of parts lists.- Decision support systems with adaptive reasoning strategies.- Knowledge discovery in databases - An inductive logic programming approach.- The composition heuristic.- The job assignment problem: A study in parallel and distributed machine learning.- Self-improving behavior arbitration.- Neural networks for manipulator path planning.- Path planning using a subgoal graph.- A nonlinear markovian characterization of time series using neural networks.- Feature-based perception of semantic concepts.- Automatic detection of thesaurus relations for information retrieval applications.- InfoSphere ? -V: a new approach to 3D-visualization of information.

Pattern Matching and Text Compression Algorithms.

Abstract: Pattern matching is the problem of locating a specific pattern inside raw data. The pattern is usually a collection of strings described in some formal language. Applications require two kinds of solution depending upon which string, the pattern, or the text, is given first. Solutions based on the use of automata or combinatorial properties of strings are commonly implemented to preprocess the pattern. The notion of indices realized by trees or automata is used in the second kind of solutions. The aim of data compression is to provide representation of data in a reduced form in order to save both storage place and transmission time. There is no loss of information, the compression processes are reversible. Pattern-matching and text-compression algorithms are two important subjects in the wider domain of text processing. They apply to the manipulation of texts (word editors), to the storage of textual data (text compression), and to data retrieval systems (full text search). They are basic components used in implementations of practical softwares existing under most operating systems. Moreover, they emphasize programming methods that serve as paradigms in other fields of computer science (system or software design). Finally, they also play an important role in theoretical computer science by providing challenging problems. Although data are recorded in various ways, text remains the main way to exchange information. This is particularly evident in literature or linguistics where data are composed of huge corpora and dictionaries, but applies as well to computer science where a large amount of data is stored in linear files. And it is also the case, for instance, in molecular biology because biological molecules can often be approximated as sequences of nucleotides or amino acids. Furthermore, the quantity of available data in these fields tend to double every 18 months. This is the reason that algorithms must be efficient even if the speed and storage capacity of computers increase continuously.

Reduction and slicing of hierarchical state machines

Abstract: Formal specification languages are often criticized for being difficult to understand, difficult to use, and unacceptable by software practitioners. Notations based on state machines, such as, Statecharts, Requirements State Machine Language (RSML), and SCR, are suitable for modeling of embedded systems and eliminate many of the main drawbacks of formal specification languages. Although a specification language can help eliminate accidental complexity, the inherent complexity of many of today's systems inevitably leads to large and complex specifications. Thus, there is a need for mechanisms to simplify a formal specification and present information to analysts and reviewers in digestible chunks.

Regular Expressions and Context-Free Grammars for Picture Languages

Abstract: We introduce a new concept of regular expression and context-free grammar for picture languages (sets of matrices over a finite alphabet) and compare and connect these two formalisms.

Decision fusion and supervisor synthesis in decentralized discrete-event systems

Abstract: We study a problem in decentralized supervisory control coined the global problem (GP) by Rudie and Wonham (1992). The objective is to find local supervisors that generate languages that lie in a specified range of closed languages. We present results for a version of this problem called the special global problem, (SGP) where the lower end of the range is empty and the higher end of the range is a closed and regular "legal" language. To this end, online local supervisors are synthesized that generate a language that contains the supremal closed controllable and strongly decomposable (supCCSD) sublanguage of the legal language. We accomplish this task through a new, more general decentralized supervisory control architecture involving decision fusion. We formulate two problems that extend GP and SGP. These are GP with fusion (GPF) and SGP with fusion (SGPF). Our main result is a set of local supervisors that solve SGPF for any k-out-of-n type event fusion rule. This result is of particular interest when more than one supervisor has control over the same event. Furthermore, the local supervisor designs are decoupled, thus the (online) computation of local supervisors can be performed in a distributed manner.

Contextual grammars and formal languages

Abstract: Contextual grammars were introduced by S. Marcus in 1969 [29], in an attempt to build a bridge between analytical and generative models of natural languages. In particular, contextual grammars were “translating” the central notion of context from the analytical models into the framework of generative grammars. The chapter by S. Marcus in this handbook [31] gives a lucid account of the motivation behind contextual grammars from the natural point of view.

The Niche Hiker's Guide to Population Ecology : A logical reconstruction of organization ecology's niche theory

Abstract: Logical formalization is a formal method for the analysis of theoretical arguments in the social sciences Hannan and Freeman's organizational niche theory (1989) is rebuilt by means of First-Order Logic, and its predictions are derived as theorems Translation into a formal language makes the theory's inference structure transparent and accessible to discussion, repair and development The consistency of the model can be checked by computational means The logical approach helps to specify niche theory's domain; it paints out hidden assumptions, highlights spots where the reasoning has to be modified, and provides solid foundations for further theory building Moreover, the established premise set also allows for the deduction of some new results Logical formalization supports empirical research by delineating constraints on and explicit relations between sociological concepts, facilitating their appropriate operationalization

Accurate computation of the relative entropy between stochastic regular grammars

Abstract: Works dealing with grammatical inference of stochastic grammars often evaluate the relative entropy between the model and the true grammar by means of large test sets generated with the true distribution. In this paper, an iterative procedure to compute the relative entropy between two stochastic deterministic regular grammars is proposed.

Interconvertbility of set constraints and context-free language reachability

Abstract: We show the interconvertibility of context-free-language reachability problems and a class of set-constraint problems: given a context-free-language reachability problem, we show how to construct a set-constraint problem whose answer gives a solution to the reachability problem; given a set-constraint problem, we show how to construct a context-free-language reachability problem whose answer gives a solution to the set-constraint problem. The interconvertibility of these two formalisms offers an conceptual advantage akin to the advantage gained from the interconvertibility of finite-state automata and regular expressions in formal language theory, namely, a problem can be formulated in whichever formalism is most natural. It also offers some insight into the "O(n3) bottleneck" for different types of program-analysis problems, and allows results previously obtained for context-free-language reachability problems to be applied to set-constraint problems.

A collection of tools for making automata theory and formal languages come alive

Abstract: We present a collection of new and enhanced tools for experimenting with concepts in formal languages and automata theory. New tools, written in Java, include JFLAP for creating and simulating finite automata, pushdown automata and Turing machines; Pâte for parsing restricted and unrestricted grammars and transforming context-free grammars to Chomsky Normal Form; and PumpLemma for proving specific languages are not regular. Enhancements to previous tools LLparse and LRparse, instructional tools for parsing LL(1) and LR(1) grammars, include parsing LL(2) grammars, displaying parse trees, and parsing any context-free grammar with conflict resolution.

Optimized process planning by generative simulated annealing

Abstract: Manufacturing process planning is a difficult problem with a prohibitively large search space. It is normally tackled by decomposing goal objects into features, and then sequencing features to obtain a plan. This paper investigates an alternative approach. The capabilities of a manufacturing process are represented by a formal language of shape, in which sentences correspond to manufacturable objects. The language is interpreted to describe process plans corresponding to the shape generation, complete with cost estimates. A macro layer that describes single operations of the machine is implemented on top of the formal language. The space it describes is searched by the generative simulated annealing algorithm, a stochastic search technique based on simulated annealing. Plans that are close to the optimum are generated in reasonable time.