Design considerations for array processing languages

The Department of Energy (DoE) has a long history of large-scale scientific calculation on the most advanced ‘number-crunching’ computers. Recently, an effort to improve communications and software sharing among DoE laboratories has been underway. One result of this sharing is a project to design and implement a common language. That language turns out to be FORTRAN 77 significantly extended with new data structures, control structures and array processing. The data used to design the array processing feature is surprising and likely to be of use to others working in scientific language design; it is reported here so that others may profit from DoE's experience.     

Array automata and operations on array languages

Array automata acting on scenes (two dimensional tapes) are defined. The set of scenes accepted by array automata are proved to be equivalent to the set of arrays generated by array grammars. Certain operators like substitution, homomorphic replication and insertion are extended to sets of arrays. These operators yield interesting classes of pictures.     

Considerations for the design of array processing languages

This paper summarizes the major results of a formal survey of array processor users and indicates how these results were used in the design of a language suitable for array and vector processors. A comparison is also given with an informal survey of other large-scale computer users, which concluded that the best plan was to extend Fortran 77 to meet the requirements for array processing.     

用DLL实现与语言无关的软件开发

本文介绍WINDOWS98下VC、BCB、VB、VFP利用动态链接库共享代码的方法和技巧,并给出VC创建供其它语言调用的DLL和VC、BCB之间DLL的相互调用的源程序。     

Coding properties of DNA languages

The computation language of a DNA-based system consists of all the words (DNA strands) that can appear in any computation step of the system. In this work we define properties of languages which ensure that the words of such languages will not form undesirable bonds when used in DNA computations. We give several characterizations of the desired properties and provide methods for obtaining languages with such properties. The decidability of these properties is addressed as well. As an application we consider splicing systems whose computation language is free of certain undesirable bonds and is generated by nearly optimal comma-free codes.     

Growth properties of power-free languages

The aim of this paper is to survey the area formed by the intersection of two popular lines of research in formal language theory. The first line, originated by Thue in 1906, concerns repetition-free words and languages. The second line is the study of growth functions for words and languages; it can be traced back to the classical papers by Morse and Hedlund on symbolic dynamics (1938, 1940). Growth functions of repetition-free languages have been investigated since the 1980’s. Most of the results are obtained for power-free languages, but some ideas can be applied for languages avoiding patterns and Abelian-power-free languages as well.In this paper, we present key contributions to the area, its state of the art, and conjectures that suggest answers to some natural unsolved problems. Also, we pay much attention to the tools and techniques that made the progress in the area possible.     

Closure properties of slender languages

We investigate languages, where the number of words of every length is bounded from above by a constant independent of the length. The issues involved are very basic in the theory of formal languages and, moreover, have arisen in some recent studies in cryptography. This paper deals with closure properties of such “slender” languages with respect to a number of operations, some of them introduced very recently. Closure is considered both in general and with respect to slender languages in the families of the Chomsky hierarchy.     

Some properties of involution palindrome languages

This paper extends the understanding of involution palindrome words (θ-palindrome words). This notion is motivated by the DNA strand design in the area of biocomputing where the Watson–Crick complementarity can be abstracted as an antimorphic involution function. A language consisting of involution palindrome words is defined as an involution palindrome language. Some properties of involution palindrome words and languages are surveyed in this paper. Besides involution palindrome words being considered, some algebraic properties of skew involution palindrome words are studied as well. Furthermore, we exhibit certain characteristics of non-involution palindrome words.     

Modeling of storage properties of higher-level languages

The role of storage in the characterization of higher-level programming languages is discussed. Assignment, in particular, has significantly different meaning in different languages, which can hardly be understood without reference to an underlying model of storage. A general storage model is sketched which can be specialized to a model of ALGOL 68 or of PL/I storage. The same model is used to discuss language features allowing highly flexible data structures.Revised version of a paper presented at the ACM Symposium on Data Structures in Programming Languages, University of Florida, Gainesville, February 25–27, 1971.     

Formal properties of XML grammars and languages

We consider XML documents described by a document type definition (DTD). An XML-grammar is a formal grammar that captures the syntactic features of a DTD. We investigate properties of this family of grammars. We show that every XML-language basically has a unique XML-grammar. We give two characterizations of languages generated by XML-grammars, one is set-theoretic, the other is by a kind of saturation property. We investigate decidability problems and prove that some properties that are undecidable for general context-free languages become decidable for XML-languages. We also characterize those XML-grammars that generate regular XML-languages.

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Résumé. Nous considérons des documents XML décrits par une définition de type de document (DTD). Une grammaire XML est une grammaire formelle qui retient les aspects syntaxiques d'une DTD. Nous étudions les propriétés de cette famille de grammaires. Nous montrons qu'un langage XML a essentiellement une seule grammaire XML. Nous donnons deux caractérisations des langages engendrés par les grammaires XML, la première est ensembliste, la deuxième est par une propriété de saturation. Nous examinons des problèmes de décision et nous prouvons que certaines propriétés qui sont indécidables pour les langages context-free généraux deviennent décidables pour les langages XML. Nous caractérisons également les grammaires XML qui engendrent des langages rationnels.

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Received: 16 March 2001 / 19 March 2002     

A note on undecidable properties of formal languages

A general set of conditions is given under which a property is undecidable for a family of languages. Examples are given of the application of this result to wellknown families of languages.Research sponsored in part by the Air Force cambridge Research Laboratories, Office of Aerospace Research, USAF, under Contract F1962867C0008, and by the Air Force Office of Scientific Research, Office of Aerospace Research, USAF under Grant No. AF-AFOSR-1203-67.     

Closure properties and languages defined by bilinear automata

In this paper we define bilinear languages, via cutpoints and bilinear automata, and we obtain a necessary condition for a bilinear language to be regular. We also prove that there exists a bilinear language which is nonstochastic.     

Computationally relevant properties of natural languages and their grammars

This paper surveys what is currently known about natural language morphology and syntax from the perspective of formal language theory. Firstly, the position of natural language word-sets and sentence-sets on the formal language hierarchy is discussed. Secondly, the contemporary use by linguists of a range of formal grammars (from finite state transducers to indexed grammars) in both word-syntax (i.e. morphology) and sentencesyntax is sketched. Finally, recent developments such as feature-theory, the use of extension and unification, default mechanisms, and metagrammatical techniques, are outlined.     

Algebraic properties on the cuts of lattice-valued regular languages

In this paper, the algebraic operations on the cuts of lattice-valued regular languages are studied. Some sufficient conditions are given to guarantee the family of the cuts of lattice-valued regular languages to be closed under such algebraic operations as union, intersection, complement, quotient, homomorphism, inverse homomorphism, concatennation, reversal, etc. This work is supported by National Science Foundation of China (Grant No.10571112), “TRAPOYT” of China and National 973 Foundation Research Program (Grant No. 2002CB312200).     

Semantic properties of the root-pattern array

This paper describes a program (and a grammar) for carrying out the semantic phase of root-pattern word formation in Hebrew. This is achieved by first automatically extracting semantic features of roots from a Hebrew thesaurus. Once the roots are reduced to feature-value sets, a grammar is used to combine a specific root with a specific grammatical pattern. The result of the grammar operation yields the final set of semantic features and values for the word. Thus, the root-pattern words are not the minimal units of grammatical investigation. They are products of the grammar. In addition to the ability to automatically generate word meanings, the semantic information derived in this way can serve also for syntactic ambiguity resolution and automatic compilation of machine-oriented dictionaries, thesauri etc. The method described here can also be used for treating affixation and thus be useful for a wide scope of languages, including English, Hebrew and Finnish.     

Semantic properties of the root-pattern array

This paper describes a program (and a grammar) for carrying out the semantic phase of root-pattern word formation in Hebrew. This is achieved by first automatically extracting semantic features of roots from a Hebrew thesaurus. Once the roots are reduced to feature-value sets, a grammar is used to combine a specific root with a specific grammatical pattern. The result of the grammar operation yields the final set of semantic features and values for the word. Thus, the root-pattern words are not the minimal units of grammatical investigation. They are products of the grammar. In addition to the ability to automatically generate word meanings, the semantic information derived in this way can serve also for syntactic ambiguity resolution and automatic compilation of machine-oriented dictionaries, thesauri etc. The method described here can also be used for treating affixation and thus be useful for a wide scope of languages, including English, Hebrew and Finnish.     

Decidability and closure properties of weak Petri net languages insupervisory control

We extend the class of control problems that can be modeled by Petri nets considering the notion of weak terminal behavior. Deterministic weak languages represent closed-loop terminal behaviors that may be enforced by nonblocking Petri net supervisors if controllable. The class of deterministic weak PN languages is not closed under the supremal controllable sublanguage operator