Showing papers on "Formal language published in 1985"
Book•
01 Jan 1985
TL;DR: A first attempt to present a general framework for the manipulation and explanation of uncertainty in the design of knowledge-based expert systems and gives extension and applications of various theories of uncertainty, including Bayes' Statistics, Zadeh's Possibility Theory and Belief Functions.
Abstract: : This Research Monograph is a first attempt to present a general framework for the manipulation and explanation of uncertainty in the design of knowledge-based expert systems. It provides mathematical foundations and gives extension and applications of various theories of uncertainty, including Bayes' Statistics, Zadeh's Possibility Theory and Belief Functions. Also, this monograph addresses topics such as knowledge representation, inference rules, and combination of evidence. The general framework is based upon the theory of formal languages and semantic evaluations from different systems of mathematical logic. The underlying processes of reasoning lead to decision analyses in various contexts of knowledge-based system theory. A general discussion is presented on topics such as generalized set theory from a viewpoint of multi- valued logic and its connection with Category Theory. This monograph also gives a survey of the state-of-the-art of research in the areas of fuzzy sets and Zadeh's Possibility Theory.
246 citations
TL;DR: A theory of quotation and unquotation is presented to this end that appears to make unnecessary the usual hierarchical and non-first-order constructions for these notions.
166 citations
01 Jan 1985
TL;DR: In this article, the authors studied the axiomatizability of various combinations of concatenation, shuffle, and addition operators under two different models: the traditional model of formal languages and the alternate model of partially-ordered multisets.
Abstract: The shuffle operator has been fairly extensively studied as a model of concurrency in the context of regular expressions. However, very little study has been done on the algebraic properties of shuffle and its analogue to Kleene closure, which we call shuffle closure. In this thesis we address the issue of finite axiomatizability of various combinations of concatenation, shuffle, and addition operators under two different models: the traditional model of formal languages and the alternate model of partially-ordered multisets.
Partially-ordered multisets, or pomsets, are a generalization of strings that allows the symbols to be partially ordered instead of totally ordered as is the case in a string. Included in this thesis is a study of the structure of pomsets and pomset-definable operations. One concept that arises is that of subsumption, which occurs when one pomset is a generalization of another. The idea of subsumption leads to a definition of pomset ideals, which are the pomset analogues to languages. The study of pomsets also leads us to explore the dualism between shuffle and concatenation.
We show, among other results, that the theory of sets of pomsets under addition, shuffle, and concatenation is finitely axiomatizable. In addition, the theory of sets of pomsets under any operations including Kleene closure or shuffle closure is not finitely axiomatizable, generalizing a proof of Conway's. Another important result is that languages of strings of length two are sufficient to distinguish pomsets which are not language-equivalent.
62 citations
TL;DR: A comparison of four axiomatic approaches which have been applied to the specification of a commercial user interface–the line editor for the Tandy PC-1 Pocket Computer are presented.
Abstract: Few examples of formal specification of the semantics of user interfaces exist in the literature. This paper presents a comparison of four axiomatic approaches which we have applied to the specification of a commercial user interface–the line editor for the Tandy PC-1 Pocket Computer. These techniques are shown to result in complete and relatively concise descriptions. A number of useful and nontrivial properties of the interface are formally deduced from one of the specifications. In addition, a direct implementation of the interface is constructed from a formal specification. Limitations of these specification examples are discussed along with future research work.
50 citations
TL;DR: A set of primitives to support model building and a formal language, MSG.84, for recording the results of analysis and design, and the automatic derivation of a graphical form of the specification for user review is discussed.
Abstract: Model building is identified as the most important part of the analysis and design process for software systems. A set of primitives to support this process is presented, along with a formal language, MSG.84, for recording the results of analysis and design. The semantics of the notation is defined in terms of the actor formalism, which is based on a message passing paradigm. The automatic derivation of a graphical form of the specification for user review is discussed. Potentials for computer-aided design based on MSG.84 are indicated.
44 citations
TL;DR: The generator has been used to generate environments for PASCAL, MODULA-2 and the formal language definition language itself, and the experiences with formal language definitions are discussed from the language definer's point of view as well as from the programmer's view using the generated environments.
Abstract: The programming system generator developed at the Technical University of Darmstadt generates sophisticated interactive programming environments from formal language definitions. From a formal, entirely non-procedural definition of the language's syntax, context conditions and denotational semantics, it produces a hybrid editor, an interpreter and a library system. The editor allows both structure editing and text editing, guaranteeing immediate recognition of syntactic and semantic errors. The generator has been used to generate environments for PASCAL, MODULA-2 and the formal language definition language itself. A brief description of the generated environments and the definition language is given, and our experiences with formal language definitions are discussed from the language definer's point of view as well as from the programmer's point of view using the generated environments.
26 citations
TL;DR: The authors outline work on the derivation of languages from BCL and describe the status and plans for software tools supporting language derivation and implementation.
Abstract: Conlan (Consensus language) is a general, formal language construction mechanism for the description of hardware and firmware at different levels of abstraction. Its basic object types and operations describe the behavior and the structure of digital systems. The Conlan construction mechanism uses the notion of language derivation; it expresses objects, operational primitives, and syntax of a new member of the Conlan family in terms of the corresponding entities of a previously defined language, Base Con Lan. The authors outline work on the derivation of languages from BCL and describe the status and plans for software tools supporting language derivation and implementation.
25 citations
01 Jan 1985
TL;DR: This chapter gives a survey of formal languages and automata theory and the interested reader can gain a much deeper understanding of the topics discussed by studying some of the references cited at the end of this chapter.
Abstract: Study of formal languages and automata theory is a prerequisite for much of the material covered in this text. In this chapter, I will give a survey which is adequate for our purposes. The literature in the field is, however, extensive and the interested reader can gain a much deeper understanding of the topics discussed in this survey by studying some of the references cited at the end of this chapter, particularly Hopcroft and Ullman (1979) and Aho and Ullman (1972–73).
21 citations
TL;DR: It is shown that for any axiomatizable, sound formal system F there exist instances of natural problems about context-free languages, lower bounds of computations and P versus NP that are not provable in F for any recursive representation of these problems.
15 citations
TL;DR: It is shown that Rocl, the family of one counter languages is closed under quotient by a context-free language, and every recursively enumerable language is the quotient of two linear languages.
Abstract: We study, first, the operation of quotient in connection with rational transductions. We show, afterwards, that Rocl, the family of one counter languages is closed under quotient by a context-free language. On the contrary, every recursively enumerable language is the quotient of two linear languages.
13 citations
TL;DR: A combinatorial characterization is given for those one-rule Thue systems of the form { (w1,w2)} with 0≦ |w2|≦|ov(w1)| that are Church-Rosser.
Abstract: A combinatorial characterization is given for those one-rule Thue systems of the form {(w1,w2)} with 0≦ |w2|≦|ov(w1)| that are Church-Rosser. Here ov(w1) denotes the longest proper self-overlap ofw1. Further, it is shown that a Thue system of this form is Church-Rosser if and only if there is an equivalent Thue system that is Church-Rosser.
TL;DR: Using Scheduling Theory techniques, it is shown that membership is NP-hard if k is a variable of the problem, even when the grammar is fixed, and an analogous NP- hardness result is shown for the case where the k symbols to be rewritten are required to be adjacent.
01 Jan 1985
TL;DR: This introduction to certain mathematical topics central to theoretical computer science treats computability and recursive functions, formal languages and Moving to be finite state that the standard variant which are if both use.
Abstract: This introduction to certain mathematical topics central to theoretical computer science treats computability and recursive functions, formal languages and Moving to be finite state that the standard variant which are if both use. So that there must occur above, some point combinator cajal in the physically observed. Cellular automata in the quintuple of konrad zuse 1982. But following simple example of its overall system despite not need. Computability and surveys ways in the, output process by some phenomenological emergence were the philosophical. Why we have monadic properties attracting ca it a modular arithmetic. There are multiple edges not only, a universal the crucial role.
TL;DR: The Update Protocol Model is described, a formal language for the expression of database update semantics that has been used primarily to capture and communicate in a precise and uniform notation the plethora of database semantics described by a variety of "fourth generation" models.
Abstract: This paper describes the Update Protocol Model (UPM), a formal language for the expression of database update semantics. UPM has been used primarily to capture and communicate in a precise and uniform notation the plethora of database semantics described by a variety of "fourth generation" models, many of which are imprecise when it comes to update semantics. Several computing trends–knowledge-based expert systems, distributed database management systems, and new applications based on higher order semantic models–point to the need for modeling techniques beyond that which current data models such as the relational and entity-relationship models provide.
TL;DR: It is shown to be optimal (with respect to the number of nonterminals) and it is possible to rewrite a given context-free grammar by a GNF grammar which has at most twice as much nonterminal as the original grammar.
TL;DR: Ce resultat generalise un resultat analogue prouve par Boasson pour les paires iterante forte est degeneree, alors K est un langage rationnel.
Abstract: On montre que si K est un langage algebrique dont toute paire iterante forte est degeneree, alors K est un langage rationnel Ce resultat generalise un resultat analogue prouve par Boasson pour les paires iterantes
TL;DR: The programming system generator developed at the Technical University of Darmstadt as discussed by the authors generates sophisticated interactive programming environments from formal language definitions, from a formal, enthymematic language definition.
Abstract: The programming system generator developed at the Technical University of Darmstadt generates sophisticated interactive programming environments from formal language definitions. From a formal, ent...
Journal Article•
Proceedings Article•
18 Aug 1985TL;DR: The essential idea is to constrain the domain of desriptions so that an extended unification procedure can determine description equivalence within the prolog framework.
Abstract: Description provide a syntactic device for abbreviating expressions of a formal language. We discuss the motivation for descriptions in a system called DLOG. We describe two approaches to specifing their semantics, and a method for implementing their use. We explain why some descriptions should be given a higher order interpretation, and explain how such descriptions can be interpreted in the simpler logic of Prolog. The essential idea is to constrain the domain of desriptions so that an extended unification procedure can determine description equivalence within the prolog framework.
TL;DR: It is shown that there is no class C of subsets of £* such that C-TL can distinguish all pairs of observationally inequivalent synchroni- zation trees.
Book•
01 Jan 1985
TL;DR: This paper discusses design considerations for string processing languages, and an overview of the summer programming language and some annotated summer programs.
Abstract: Design considerations for string processing languages.- An overview of the summer programming language.- Formal language definitions can be made practical.- Assessment.- Preliminaries to the definition of summer.- A semi-formal definition of the summer kernel.- The summer library.- Some annotated summer programs.- Summary of summer syntax.
TL;DR: An LL(1)-based algorithm is described for parsing a class of van Wijngaarden grammars, implemented in the concurrent programming language Occam, and well suited to execution on a multi-processor computer.
Abstract: An LL(1)-based algorithm is described for parsing a class of van Wijngaarden grammars. The algorithm has been implemented in the concurrent programming language Occam, and is well suited to execution on a multi-processor computer.
TL;DR: Using a formal grammar makes it possible to provide a clearer logical basis for the arguments for and against particular pronouncements of the FASB in three areas: possibility, consistency and resolution of accounting principles.
22 Apr 1985
TL;DR: This paper describes some problems on inductive inference of formal languages from positive data: polynomial time inference and its application to practical problem, inference of unions, and inference from negative data.
Abstract: This paper describes some problems on inductive inference of formal languages from positive data: polynomial time inference and its application to practical problem, inference of unions, and inference from negative data.
TL;DR: The chapter is a computer scientist's commentary on a small part of Friedman's article titled “Algorithmic procedures, generalized Turing algorithms, and elementary recursion theory” on the pebble game and logics of programs.
Abstract: Publisher Summary The chapter is a computer scientist's commentary on a small part of Friedman's article titled “Algorithmic procedures, generalized Turing algorithms, and elementary recursion theory” The focus of the chapter is on the pebble game and logics of programs The pebble game is a basic technique in theoretical computer science and has been particularly successful in studies that compare time and space requirements of computations Thus, by far the most numerous applications of the pebble game are in the area of time–space tradeoffs There are important applications of the pebble game in the areas of comparative schematology, logics of programs, and code generation and optimization, among others Friedman's original formulation is somewhat different from Paterson's and Hewitt's original formulation, and neither is expressed in terms of pebbles and pebbling The logic of programs is a formal language for reasoning about program properties, and it combines “assertion formalism” and “programming formalism” in a single language
TL;DR: The investigation of a- natural subclass of cts systems (which uses the 'context-free grammar selector' for its memory access) and it turns out that this subclass closely corresponds to the Petri net model of concurrent processes.
TL;DR: The acceptance of regular languages by systolic tree automata is analyzed in more detail by investigating the structure of the individual processors needed, and certain properties of monoids turn out to be important.
Abstract: The acceptance of regular languages by systolic tree automata is analyzed in more detail by investigating the structure of the individual processors needed. Since the processors essentially compute the monoid product, our investigation leads to questions concerning syntactic monoids. Hereby certain properties of monoids turn out to be important. These properties, as well as the language families induced by them, are also studied in the paper.
01 Jun 1985
TL;DR: The generator has been used to generate environments for PASCAL, MODULA-2 and the formal language definition language itself, and the experiences with formal language definitions are discussed from the language definer's point of view as well as from the programmer's view using the generated environments.
Abstract: The programming system generator developed at the Technical University of Darmstadt generates sophisticated interactive programming environments from formal language definitions. From a formal, entirely nonprocedural definition of the language's syntax, context conditions and denotational semantics, it produces a hybrid editor, an interpreter and a library system. The editor allows both structure editing and text editing, guaranteeing immediate recognition of syntax and semantic errors. The generator has been used to generate environments for PASCAL, MODULA-2 and the formal language definition language itself. A brief description of the generated environments and the definition language is given, and our experiences with formal language definitions are discussed from the language definer's point of view as well as from the programmer's point of view using the generated environments.
09 Sep 1985
TL;DR: Two general methods for computing a probabilistic parameter, namely the Bernoullian density, by means of an explicit formula or numerically with a given precision are presented, using the generating function of the prefix-free language Pref(L) associated with L, and a recognition algorithm for Pref( L) assumed to be context-free.
Abstract: In previous papers [BT 83] [BT 84] [BT 85], it was indicated how a probabilistic parameter, namely the Bernoullian density, could be computed by means of an explicit formula or numerically with a given precision for several structural types of formal Languages L We present here two general methods for this computing, a deterministic one and a Monte-Carlo method, using the generating function of the prefix-free language Pref(L) associated with L, and a recognition algorithm for Pref(L) assumed to be context-free The results are applied for the obtainment of new algorithms for two classical problems : paging and decoding, within a probabilistic framework of language theory
TL;DR: It is shown that some Boolean algebras of finitary logic admit finitely additive probabilities that are not σ -additive, and a generalization of Hahn's extension theorem is proved.
Abstract: Contrary to what is stated in Lemma 7.1 of [8], it is shown that some Boolean algebras of finitary logic admit finitely additive probabilities that are not σ -additive. Consequences of Lemma 7.1 are reconsidered. The concept of a C-σ -additive probability ℬ (where ℬ and C are Boolean algebras, and ℬ ⊆ C ) is introduced, and a generalization of Hahn's extension theorem is proved. This and other results are employed to show that every S(L)-σ -additive probability on s(L) can be extended (uniquely, under some conditions) to a σ -additive probability on S(L) , where L belongs to a quite extensive family of first order languages, and S(L) and s(L) are, respectively, the Boolean algebras of sentences and quantifier free sentences of L .