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Showing papers on "Formal language published in 1989"


Proceedings ArticleDOI
05 Jun 1989
TL;DR: The author gives a calculus based on a categorical semantics for computations, which provides a correct basis for proving equivalence of programs, independent from any specific computational model.
Abstract: The lambda -calculus is considered a useful mathematical tool in the study of programming languages. However, if one uses beta eta -conversion to prove equivalence of programs, then a gross simplification is introduced. The author gives a calculus based on a categorical semantics for computations, which provides a correct basis for proving equivalence of programs, independent from any specific computational model. >

957 citations


Book
01 Jan 1989
TL;DR: This book presents 25 different regulating mechanisms by definitions, examples and basic facts, especially concerning hierarchies, as well as selective substitution grammars as one common generalization.
Abstract: It is well-known that context-free grammars cannot cover all aspects of natural languages, progamming languages and other related fields. Therefore a lot of mechanisms have been introduced which control the application of context-free rules. This book presents 25 different regulating mechanisms by definitions, examples and basic facts, especially concerning hierarchies. Matrix, programmed, and random context grammars as typical representants are studied in more detail. Besides their algebraic and decidability properties a comparison is made with respect to syntactic complexity measures and pure versions. Further topics are combinations of some control mechanisms, regulated L systems, automata characterizations, Szilard languages, and grammar forms of regulated grammars as well as selective substitution grammars as one common generalization.

847 citations


Book ChapterDOI
01 Jan 1989
TL;DR: For a long time, the word ‘quantifier’ in linguistics and philosophy simply stood for the universal and existential quantifiers of standard predicate logic, but the dominance of predicate logic has obscured the fact that the quantifier expressions form a syntactic category, with characteristic interpretations, and with many more members than ∀ and ∃.
Abstract: For a long time, the word ‘quantifier’ in linguistics and philosophy simply stood for the universal and existential quantifiers of standard predicate logic. In fact, this use is still prevalent in elementary textbooks. It seems fair to say that the dominance of predicate logic in these fields has obscured the fact that the quantifier expressions form a syntactic category, with characteristic interpretations, and with many more members than ∀ and ∃.

206 citations


Journal ArticleDOI
TL;DR: Some algebraic structures of the set of all effects are investigated and summarized in the notion of a (weak) orthoalgebra and it is shown that these structures can be embedded in a natural way in lattices, via the so-called MacNeille completion.
Abstract: Some algebraic structures of the set of all effects are investigated and summarized in the notion of a(weak) orthoalgebra. It is shown that these structures can be embedded in a natural way in lattices, via the so-calledMacNeille completion. These structures serve as a model ofparaconsistent quantum logic, orthologic, andorthomodular quantum logic.

205 citations


Journal ArticleDOI
TL;DR: This paper provides an introduction to the description of information systems using formal, mathematical specifications written in the Z notation, and to the refinement of these specifications into rigorously checked designs.
Abstract: This paper provides an introduction to the description of information systems using formal, mathematical specifications written in the Z notation, and to the refinement of these specifications into rigorously checked designs. The first part introduces the idea of a formal specification using a simple example: that of a ‘birthday book’ in which people's birthdays can be recorded, and which is able to issue reminders on the appropriate day. The behaviour of this system for correct input is specified first; then the schema calculus is used to strengthen the specification into one requiring error reports for incorrect input. The second part of the paper introduces the idea of data refinement as the primary means of constructing designs which achieve a formal specification. Refinement is presented through the medium of two examples: the first is a direct implementation of the birthday book from part one; and the second is a simple checkpoint facility, which allows the current state of a database to be saved and later restored. A Pascal-like programming language is used to show the code for some of the operations in the examples.

166 citations


Book
01 Jan 1989
TL;DR: Logic grammars have found wide application both in natural language processing and in formal applications such as compiler writing, and this book introduces the main concepts involving natural and formal language processing in logic programming.
Abstract: Logic grammars have found wide application both in natural language processing and in formal applications such as compiler writing. This book introduces the main concepts involving natural and formal language processing in logic programming, and discusses typical problems which the reader may encounter, proposing various methods for solving them. The basic material is presented in depth; advanced material, involving new logic grammar formalisms and applications, is presented with a view towards breadth. Major sections of the book include: grammars for formal language and linguistic research, writing a simple logic grammar, different types of logic grammars, applications, and logic grammars and concurrency. This book is intended for those interested in logic programming, artificial intelligence, computational linguistics, Fifth Generation computing, formal languages and compiling techniques. It may be read profitably by upper-level undergraduates, post-graduate students, and active researchers on the above-named areas. Some familiarity with Prolog and logic programming would be helpful; the authors, however, briefly describe Prolog and its relation to logic grammars. After reading Logic Grammars, the reader will be able to cope with the ever-increasing literature of this new and exciting field.

95 citations


Proceedings ArticleDOI
21 Jun 1989
TL;DR: This work presents metalanguage enhancements for context-free grammars that allow the syntax of programming languages to be completely described in a single grammar.
Abstract: The disadvantages of traditional two-phase parsing (a scanner phase preprocessing input for a parser phase) are discussed. We present metalanguage enhancements for context-free grammars that allow the syntax of programming languages to be completely described in a single grammar. The enhancements consist of two new grammar rules, the exclusion rule, and the adjacency-restriction rule. We also present parser construction techniques for building parsers from these enhanced grammars, that eliminate the need for a scanner phase.

89 citations


Journal ArticleDOI
TL;DR: A direct and constructive proof is given that every regular language is the homomorphic image of a splicing language as defined by Head.
Abstract: A direct and constructive proof is given that every regular language is the homomorphic image of a splicing language as defined by Head. The class of splicing languages involved have a particularly simple presentation and are regular. Also presented are some examples which demonstrate the relation of the class of splicing languages to that of regular languages and an example of a regular language which is not a splicing language.

58 citations


Journal ArticleDOI
TL;DR: This is the first of a sequence of papers in which this approach takes recursion to be a fundamental (primitive) process for constructing algorithms, not a derived notion which must be reduced to others—e.g. iteration or application and abstraction.
Abstract: This is the first of a sequence of papers in which we will develop a foundation for the theory of computation based on a precise, mathematical notion of abstract algorithm. To understand the aim of this program, one should keep in mind clearly the distinction between an algorithm and the object (typically a function) computed by that algorithm. The theory of computable functions (on the integers and on abstract structures) is obviously relevant to this work, but we will focus on making rigorous and identifying the mathematical properties of the finer (intensional) notion of algorithm.It is characteristic of this approach that we take recursion to be a fundamental (primitive) process for constructing algorithms, not a derived notion which must be reduced to others—e.g. iteration or application and abstraction, as in the classical λ-calculus. We will model algorithms by recursors, the set-theoretic objects one would naturally choose to represent (syntactically described) recursive definitions. Explicit and iterative algorithms are modelled by (appropriately degenerate) recursors.The main technical tool we will use is the formal language of recursion, FLR, a language of terms with two kinds of semantics: on each suitable structure, the denotation of a term t of FLR is a function, while the intension of t is a recursor (i.e. an algorithm) which computes the denotation of t. FLR is meant to be intensionally complete, in the sense that every (intuitively understood) “algorithm” should “be” (faithfully modelled, in all its essential properties by) the intension of some term of FLR on a suitably chosen structure.

56 citations


01 Jan 1989
TL;DR: In a series of articles and talks as discussed by the authors, Kamp has developed a theory of natural language interpretation that uses discourse representations, and the most interesting applications of the theory are the problem of discourse anaphora to indefinites, donkey sentences and temporal processing.
Abstract: In a series of articles and talks I Hans Kamp has developed a theory of natural language interpretation that uses discourse representations. The most interesting applications of the theory are the problem of discourse anaphora to indefinites, donkey sentences and temporal processing. It seems likely that the theory can be successfully applied to a range of furlLher questions in natural language semantics. The theory is difficult to compare with Montague Grammar and related approaches to natural language semantics since the system Kamp presents is not a grammar in the sense of Montague (1970). The notion of a grammar in that article is a mathematically precise interpretation of the compositionality principle. Montague requires the syntax and the semantics of the grammar to be expressed as algebras. The relation between the syntactic and the semantic objects must be given as a honaomorphism from the syntactical algebra to the (polynomial closure of) the semantic algebra. If a logical representation language is used in the formulation of the grammar, the relation between the syntactical objects and their representations, and between the representation and their meanings, must again be expressed as homomorphisms between the relevant algebras. In this way, the composition of both homomorphisms is itself a homomorphism between syntax and semantics. The level of representation has thereby only a secondary status in the theory: it helps to develop the grammar by making it more perspicuous, but one can in principle eliminate it in favor of the homomorphism from syntax to semantics it induces. It is the aim of this paper to provide a version of Kamp's ideas that is a grammar in the sense of Montague. In the first part, discourse representation structures will be analysed as a formal language: i.e., a compositional ~ interpretation will be provided. In the second part a fragment of natural language will be defined with a translation in the representation language given in the first part. The fragment is an extension and revision of the fragment in (Kamp, 1981b). Besides comparison with more conventional approaches, there are other reasons for being interested in a compositional formulation of Kamp's ideas. Compositional treatments are supported by a simple theory of how compound expressions get their meaning: it is a function

55 citations


Journal ArticleDOI
TL;DR: The main result is that there exist sequential splicing systems with recursively unsolvable membership problem and the technique of the proof is to embed Turing machine computations in the languages.
Abstract: The notion of splicing system has been used to abstract the process of DNA digestion by restriction enzymes and subsequent religation. A splicing system language is the formal language of all DNA strings producible by such a process. The membership problem is to devise an algorithm (if possible) to answer the question of whether or not a given DNA string belongs to a splicing system language given by initial strings and enzymes. In this paper the concept of a sequential splicing system is introduced. A sequential splicing system differs from a splicing system in that the latter allows arbitrarily many copies of any string in the initial set whereas the sequential splicing system may restrict the initial number of copies of some strings. The main result is that there exist sequential splicing systems with recursively unsolvable membership problem. The technique of the proof is to embed Turing machine computations in the languages.

Book
01 Feb 1989
TL;DR: This theory of finite automata with an introduction to formal languages book will probably make you feel curious and take this theory to have willing to reach all benefits.
Abstract: When there are many people who don't need to expect something more than the benefits to take, we will suggest you to have willing to reach all benefits. Be sure and surely do to take this theory of finite automata with an introduction to formal languages that gives the best reasons to read. When you really need to get the reason why, this theory of finite automata with an introduction to formal languages book will probably make you feel curious.

Book
01 Jan 1989
TL;DR: In this article, Sunitha and Kalyani present a formal language and automata theory for regular expressions and finite automata, which is free to download, and also includes solution sets.
Abstract: Guyz, i need dis book. I downloaded from google books but some pages are not available so. I ll b thankful to one who ll help.a formal grammar and it is more capable than a finite-state machine but. 2K.V.N Sunitha,N Kalyani Formal Languages and automata theoryTata. Formal Languages and Automata Theory. Regular Expressions and Finite Automata. Best of all, its free to download, and also includes solution sets.

Posted Content
TL;DR: Viewing procedures as formal conversations, this paper presents a representation schema and grammar to model these conversations and initiate the development of a formal language by which users can cooperate, negotiate, and make commitments over a performative network.
Abstract: Electronic Data Interchange (EDI) is a telecommunications system that many view as the next major productivity gain made possible by information technology. This paper discusses how our semantic, procedure-oriented view of business transactions leads to a different kind of telecommunications system -- a performative network. Viewing procedures as formal conversations, we present a representation schema and grammar to model these conversations and initiate the development of a formal language by which users can cooperate, negotiate, and make commitments over a performative network. Our approach complements and extends EDI's syntactic, record-format orientation, seeking to express not only the data transmitted through these transactions but also the semantics of the procedures themselves.

Journal ArticleDOI
TL;DR: It is proved that the membership problem for context free trace languages can be solved in time O ( BM ( n α )), where α is the dimension of the greatest clique of the concurrency relation C and BM is the time required for multiplying two arbitrary n × n boolean matrices.
Abstract: Trace languages have been introduced in order to describe the behaviour of concurrent systems in the same way as usual formal languages do for sequential system. They can be defined as subsets of a free partially commutative monoid and a theory of trace languages can be developed, generalizing the usual formal languages theory. In this paper, the time complexity of membership problems for regular and context-free trace languages is investigated. It is proved that the membership problem for context free trace languages can be solved in time O ( BM ( n α )), where α is the dimension of the greatest clique of the concurrency relation C and BM ( n ) is the time required for multiplying two arbitrary n × n boolean matrices. For regular trace languages, our method gives an algorithm which requires O ( n α ) time. Finally, the uniform membership problem is shown to be NP-complete.

Book ChapterDOI
14 Jun 1989
TL;DR: The parser is an extension of Earley's algorithm, which was originally developed for context free string grammars, and is able to recognize not only complete structures generated by a plex grammar but also partial ones.
Abstract: Plex grammars according to [13], generating two-dimensional plex structures, are a generalization of string grammars. In this paper we describe a parser for context free plex grammars. The parser is an extension of Earley's algorithm, which was originally developed for context free string grammars. Our parser is able to recognize not only complete structures generated by a plex grammar but also partial ones. The algorithm has been implemented and tested on a number of examples. The time complexity of the parser is exponential in general, but there exist subclasses of plex languages for which the parser has a polynomial time complexity.

Journal ArticleDOI
TL;DR: This paper is an attempt to clarify the situation by showing that, modulo a small, decidable class of formulas irrelevant to these applications, IL and Ty2 are equivalent in the strong sense that there exists a reversible translation between the terms of either language.
Abstract: Among the symbolic languages used most frequently in the indirect interpretation of natural language are Montague's Intensional Logic IL [5, 384ff.] and its extensional counterpart, the language Ty2 of two-sorted type theory. The question of which of these two formal languages is to be preferred has been obscured by lack of knowledge about the exact relation between them. The present paper is an attempt to clarify the situation by showing that, modulo a small, decidable class of formulas irrelevant to these applications, IL and Ty2 are equivalent in the strong sense that there exists a reversible translation between the terms of either language.In [3, 6Iff.] Gallin has shown that there exists a simple and natural translation * of IL into Ty2. Following Gallin's translation procedure, it is even possible to conceive of IL as a highly restricted sublanguage of Ty2, viz. as that part which only contains expressions of certain intensional types plus one variable of the basic type of indices or worlds. In an obvious sense, this sublanguage has less expressive power than the whole of Ty2, where it is possible to express conditions on entities that do not even exist in IL's ontology. However, by a certain amount of coding, one can translate Ty2 into IL [3, 105]. Conditions on nonintensional entities then become conditions on corresponding intensional objects; and these paraphrases preserve (standard) validity and entailment. On the other hand, this retranslation of Ty2 into IL is not an inversion of *, as can be seen from a simple example.

Proceedings ArticleDOI
Mats Andersson1
16 Dec 1989
TL;DR: Omola (object-oriented modelling language), a language for structured dynamic models, is presented and is designed to be general and extensible in order to employ future, as yet unpredicted, model representation concepts.
Abstract: Omola (object-oriented modelling language), a language for structured dynamic models, is presented. The language is based on ideas from object-oriented programming. Models are represented as classes with attributes. Inheritance and hierarchical submodel decomposition improve model structure and facilitate reuse of models. The language is designed to be general and extensible in order to employ future, as yet unpredicted, model representation concepts. A few examples of extensions are given. >

Journal ArticleDOI
TL;DR: It is shown that a LARGE class of DETERMINISTIC LINEAR CFL''s are in UNIFORM TC(SUPERSCRIPT)0, but that some are complete for UNIForM NC(SUPerscriptT)1.

Journal ArticleDOI
TL;DR: In this paper, it was shown that the most usual finiteness conditions on a subgroup of a finitely generated group all have equivalent formulations in terms of formal language theory.
Abstract: We show in this article that the most usual finiteness conditions on a subgroup of a finitely generated group all have equivalent formulations in terms of formal language theory. This correspondence gives simple proofs of various theorems concerning intersections of subgroups and the preservation of finiteness conditions in a uniform manner. We then establish easily the theorems of Greibach and of Griffiths by considering free reductions of languages that describe the computations of pushdown automata in one case and of Turing machines in the other, thus making clear that they are essentially the same.

Journal ArticleDOI
TL;DR: It is proved that an extended version of scattered grammars produces exactly the context-sensitive languages.
Abstract: We study the relationship between scattered and context-sensitive rewriting. We prove that an extended version of scattered grammars produces exactly the context-sensitive languages. Also unordered scattered context languages are a proper subset of scattered context languages, and unordered scattered rewriting with erasing does not generate all scattered context (and thus not all context-sensitive) languages.

Journal Article
TL;DR: The limit set on finite lattices is shown to be neither a regular nor an unambiguous context-free language for certain additive rules with chaotic behavior, and for rules that can simulate one of these additive rules t hrough a blocking transformation.
Abstract: A bst ract. A one-dimensional cellular automaton rule with specified boundary conditions can be considered as acting simultaneously on all finite lattices, which gives a mapping between formal languages. Regular lang uages are always mapped to regular langu ages, contex t-free to context-free, context-sensitive to context-sensitive, and recursive sets to recursive sets . In particular, the finite time sets on finite lattices are regular languages. The limit set on finite lattices (t he periodic set) is shown to be neither a regular nor an unambiguous context-free language for certain additive rules with chaotic behavior, and for rules that can simulate one of these additive rules t hrough a finit e blocking transformation. The relation between cellular automata on finite and infinite lattices is discussed .

Proceedings ArticleDOI
05 Jun 1989
TL;DR: A language paradigm called shared dataspace is defined that causes computations to be performed using an anonymous, content-addressable communication medium acted upon by atomic transactions to probe the essence of this paradigm.
Abstract: A language paradigm called shared dataspace is defined that causes computations to be performed using an anonymous, content-addressable communication medium acted upon by atomic transactions. To probe the essence of this paradigm, a relatively simple shared dataspace language called Swarm is defined. An overview is presented of the Swarm language. A formal operational model for the language is given and some of the programming implications and distinctive features of the model and language are discussed. Swarm programming strategies are examined using a series of related example programs. >

Proceedings ArticleDOI
19 Jun 1989
TL;DR: It is shown that it is possible to decompose any level of NC into components involving lower levels, and the results are extended to the class AC.
Abstract: It is shown that it is possible to decompose any level of NC into components involving lower levels. The results are extended to the class AC. The method presented results in a natural way to provide NC and AC with oracles. >

Journal ArticleDOI
TL;DR: The combinatorial structure of n-prefix-suffix languages, called n-ps-codes in this paper, is investigated.
Abstract: The combinatorial structure of n-prefix-suffix languages, called n-ps-codes in this paper, is investigated. An n-ps-code is a language, each of whose subsets of cardinality at most n is a prefix code or a suffix code.

Journal Article
TL;DR: A model is presented to characterize the class of languages obtained by adding reduplication to context-free languages, which appears capable of accommodating the sort of reduplications that have been observed to occur in natural languages, but which excludes many of the unnatural constructions.
Abstract: A model is presented to characterize the class of languages obtained by adding reduplication to context-free languages. The model is a pushdown automaton augmented with the ability to check reduplication by using the stack in a new way. The class of languages generated is shown to lie strictly between the context-free languages and the indexed languages. The model appears capable of accommodating the sort of reduplications that have been observed to occur in natural languages, but it excludes many of the unnatural constructions that other formal models have permitted.

Journal ArticleDOI
TL;DR: An interactive system in which knowledge is represented as production rules in a format derived from the theory of formal languages is described, finding that knowledge represented at a low theoretical level fails to descriminate between the input from informants and the intuitive assumptions of analysts, but experimental procedures can be improved considerably if the system is designed to perform automated knowledge acquisition.
Abstract: A major problem in ethnographic description may be summed up as the search for ways to disentangle folk from analytical models. Knowledge-based systems have contributed to the development of formal structures for the manipulation of symbols associated with particular physical and conceptual phenomena. Importantly, their output can be interpreted by experts in the domain. This provides evaluation procedures for models elaborated jointly by analysts and informants. This paper describes an interactive system in which knowledge is represented as production rules in a format derived from the theory of formal languages. Modus ponens and modus tollens are explained and compared to derivation schemata in first-order predicate logic. The results of an application to the study of North Indian tabla drumming are assessed. We conclude that (1) knowledge represented at a low theoretical level fails to descriminate between the input from informants and the intuitive assumptions of analysts, (2) experimental procedures can be improved considerably if the system is designed to perform automated knowledge acquisition (using probabilistic grammars and inductive learning).

Journal ArticleDOI
TL;DR: The linguistic approach presented in this paper attempts to offer new perspectives and modeling methodology in the study of manufacturing systems to address issues such as production feasibility, machine assignment, and robustness as linguistic problems.

Book ChapterDOI
03 Jul 1989
TL;DR: This paper follows previous work on the Formal Language of Recursion FLR and develops intensional (algorithmic) semantics for it: the intension of a term t on a structure A is a recursor, a set-theoretic object which represents the (abstract, recursive) algorithm defined by t on A.
Abstract: This paper follows previous work on the Formal Language of Recursion FLR and develops intensional (algorithmic) semantics for it: the intension of a term t on a structure A is a recursor, a set-theoretic object which represents the (abstract, recursive) algorithm defined by t on A. Main results are the soundness of the reduction calculus of FLR (which models faithful, algorithm-preserving compilation) for this semantics, and the robustness of the class of algorithms assigned to a structure under algorithm adjunction.

Proceedings ArticleDOI
Toshimitsu Ushio1
13 Dec 1989
TL;DR: In this paper, it was shown that the controllability of the legal language for a given predicate is equivalent to that for the corresponding reachability set, and the relationship between the supremal controllable subpredicate of the predicate and the supremally controllably sublanguage of the corresponding legal language was dealt with.
Abstract: In discrete-event systems two control techniques, called supervisory control and state feedback logic, have been proposed. It is shown that controllability of the legal language for a given predicate is equivalent to that for the corresponding reachability set. The relationship between the supremal controllable subpredicate of the predicate and the supremal controllable sublanguage of the corresponding legal language is then dealt with. >