Showing papers on "Context-sensitive grammar published in 1997"
01 Apr 1997
TL;DR: A tree generating system called tree-adjoining grammar (TAG) is described and a number of formal results have been established for TAGs, which are of interest to researchers in formal languages and automata, including those interested in tree grammars and tree automata.
Abstract: In this paper, we will describe a tree generating system called tree-adjoining grammar (TAG) and state some of the recent results about TAGs. The work on TAGs is motivated by linguistic considerations. However, a number of formal results have been established for TAGs, which we believe, would be of interest to researchers in formal languages and automata, including those interested in tree grammars and tree automata.
787 citations
Book•
01 Jan 1997
TL;DR: 1. Origin and Motivation, Formal Language Theory Prerequisites, and A Generalization: n-Contextual Grammars.
Abstract: 1. Origin and Motivation. 2. Formal Language Theory Prerequisites. 3. Contexts (Adjoining) Everywhere. 4. Basic Classes of Contextual Grammars. 5. Generative Capacity. 6. Language Theoretic Properties. 7. Linguistically Relevant Properties. 8. Grammars with Restricted Selection. 9. Grammars with Minimal/Maximal Use of Selectors. 10. Variants of Contextual Grammars. 11. Two-Level Contextual Grammars. 12. Regulated Contextual Grammars. 13. A Generalization: n-Contextual Grammars. 14. A Dual Model: Insertion Grammars. 15. Further Topics. 16. Open Problems and Research Topics. Bibliography. Subject Index.
179 citations
TL;DR: A structural characterisation of the reachable markings of Petri nets in which every transition has exactly one input place is provided, and the reachability problem for this class is proved to be NP-complete.
Abstract: The paper provides a structural characterisation of the reachable markings of Petri nets in which every transition has exactly one input place. As a corollary, the reachability problem for this class is proved to be NP-complete. Further consequences are: the uniform word problem for commutative context-free grammars is NP-complete; weak-bisimilarity is semidecidable for Basic Parallel Processes.
151 citations
01 Jan 1997
TL;DR: This chapter discusses certain most characteristic links between proof theory and formal grammars and 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.
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.
102 citations
Posted Content•
TL;DR: Tree Adjoining Grammar (TAG) is described as a system that arises naturally in the process of lexicalizing CFGs, and can be compared directly to an Meaning-Text Model (MTM).
Abstract: The central role of the lexicon in Meaning-Text Theory (MTT) and other dependency-based linguistic theories cannot be replicated in linguistic theories based on context-free grammars (CFGs). We describe Tree Adjoining Grammar (TAG) as a system that arises naturally in the process of lexicalizing CFGs. A TAG grammar can therefore be compared directly to an Meaning-Text Model (MTM). We illustrate this point by discussing the computational complexity of certain non-projective constructions, and suggest a way of incorporating locality of word-order definitions into the Surface-Syntactic Component of MTT.
85 citations
27 Feb 1997
TL;DR: A new concept of regular expression and context-free grammar for picture languages (sets of matrices over a finite alphabet) is introduced and these two formalisms are compared and connected.
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.
57 citations
Proceedings Article•
01 Jan 1997
56 citations
TL;DR: The Chomsky Conjecture is proved for both the full Lambek calculus and its product-free fragment, and a construction of context-free grammars involving only product- free types is presented.
Abstract: In this paper we prove the Chomsky Conjecture (all languages recognized by the Lambek calculus are context-free) for both the full Lambek calculus and its product-free fragment.For the latter case we present a construction of context-free grammars involving only product-free types.
51 citations
23 Apr 1997
TL;DR: A context sensitive graph grammar called reserved graph grammar is presented which can explicitly, efficiently and completely describe the syntax of a wide range of diagrams using labeled graphs and its parsing algorithm is of polynomial time complexity in most cases.
Abstract: When implementing textual languages, formal grammars are commonly used to facilitate understanding languages and creating parsers. In the implementation of a diagrammatic visual programming language (VPL), this rarely happens, though graph grammars with their well established theoretical background may be used as a natural and powerful syntax definition formalism. Yet all graph grammar parsing algorithms presented up to now are either unable to recognize interesting visual languages or tend to be hopelessly inefficient (with exponential time complexity) when applied to graphs with a large number of nodes and edges. The paper presents a context sensitive graph grammar called reserved graph grammar which can explicitly, efficiently and completely describe the syntax of a wide range of diagrams using labeled graphs. Moreover its parsing algorithm is of polynomial time complexity in most cases.
50 citations
01 Mar 1997
TL;DR: A collection of new and enhanced tools for experimenting with concepts in formal languages and automata theory, written in Java, include JFLAP for creating and simulating finite automata, pushdown automata and Turing machines, and PumpLemma for proving specific languages are not regular.
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.
49 citations
Proceedings Article•
01 Jan 1997
TL;DR: It is shown, in terms of crossing rates and in coverage, that when training material is limited, SCG estimation using the Minimum Description Length Principle is preferable to SCGs estimation using an indifferent prior.
Abstract: Stochastic categorial grammars (SCGs) are introduced as a more appropriate formalism for statistical language learners to est imate than stochastic context free grammars. As a vehicle for demonstrating SCG estimation, we show, in terms of crossing rates and in coverage, that when training material is limited, SCG estimation using the Minimum Description Length Principle is preferable to SCG estimation using an indifferent prior.
01 Jan 1997
TL;DR: This chapter contains sections titled: Motivation, The Approximation Method, Formal Properties, Implementation and Example, Informal Analysis, Related Work and Conclusions, Appendix—APSG formalism and example.
Abstract: This chapter contains sections titled: Motivation, The Approximation Method, Formal Properties, Implementation and Example, Informal Analysis, Related Work and Conclusions, Appendix—APSG formalism and example, Acknowledgments, References
TL;DR: It is shown that all the three basic non-context-free constructions in natural languages, that is, multiple agreements, crossed agreements, and duplication, can be realized using this type of grammars and that these languages are parsable in polynomial time.
TL;DR: This paper investigates the concept of unconditional transfer within various forms of regulated grammars like programmedgrammars, matrix grammar, grammarts with regular control, gramMars controlled by bicoloured digraphs, periodically time-variant grammARS and variants thereof, especially regarding their descriptive capacity.
Abstract: In this paper, we investigate the concept of unconditional transfer within various forms of regulated grammars like programmed grammars, matrix grammars, grammars with regular control, grammars controlled by bicoloured digraphs, periodically time-variant grammars and variants thereof, especially regarding their descriptive capacity. In this way, we solve some problems from the literature. Furthermore, we correct a construction from the literature. Most of the results of the present paper have been announced in [11].
TL;DR: The family of recursively enumerable languages is characterized by scattered context Grammars with four nonterminals if these grammars start their derivations from a word rather than a symbol.
Abstract: The family of recursively enumerable languages is characterized by scattered context grammars with four nonterminals. Moreover, this family is characterized by scattered context grammars with three nonterminals if these grammars start their derivations from a word rather than a symbol. Three open problem areas are suggested
Journal Article•
Book•
01 Jan 1997
TL;DR: The author’s research has focused on parsing of Context-Free Languages, which combines Grammar Systems, Contextual Grammars and Formal Languages, and String Editing and Longest Common Subsequences.
Abstract: of Volume 2.- 1. Complexity: A Language-Theoretic Point of View.- 2. Parsing of Context-Free Languages.- 3. Grammars with Controlled Derivations.- 4. Grammar Systems.- 5. Contextual Grammars and Natural Languages.- 6. Contextual Grammars and Formal Languages.- 7. Language Theory and Molecular Genetics.- 8. String Editing and Longest Common Subsequences.- 9. Automata for Matching Patterns.- 10. Symbolic Dynamics and Finite Automata.- 11. Cryptology: Language-Theoretic Aspects.
25 Aug 1997
TL;DR: A Chomsky normal form theorem is proved for multiplicative valence Grammars, thereby solving the open question of the existence of normal forms for unordered vector grammars and giving an alternative proof of the inclusion of context-free un ordered vector languages in LOG(CFL).
Abstract: Valences are a very simple and yet powerful method of regulated rewriting. In this paper we give an overview on different aspects of this subject. We discuss closure properties of valence languages. It is shown that matrix grammars can be simulated by valence grammars over finite monoids. A Chomsky normal form theorem is proved for multiplicative valence grammars, thereby solving the open question of the existence of normal forms for unordered vector grammars. This also gives an alternative proof of the inclusion of context-free unordered vector languages in LOG(CFL). Moreover, we investigate valences in parallel systems, thereby solving part of open problems posted in [5, p. 267].
TL;DR: It is shown that derivation trees in the generalized Lambek calculus can be transformed to a normal form, and this fact is employed in the proof of the inclusion of the class of phrase languages generated by categorial grammars based on the generalized lambek calculus.
Abstract: We show that derivation trees in the generalized Lambek calculus can be transformed to a normal form. This fact is employed in the proof of the inclusion of the class of phrase languages generated by categorial grammars based on the generalized Lambek calculus in the class of phrase languages generated by categorial grammars based on the generalized Ajdukiewicz calculus.
TL;DR: The mechanical transformation of an unambiguous context-free grammar into a deenite-clause grammar (DCG) is discussed using a nite set of examples and how a higher-order DCG can be systematically constructed using a matching procedure for simply-typed-terms is shown.
Abstract: > We discuss the mechanical transformation of an unambiguous context-free grammar (CFG) into a deenite-clause grammar (DCG) using a nite set of examples, each of which is a pair hs; mi, where s is a sentence belonging to the language deened by the CFG and m is the semantic representation (meaning) of s. The resulting DCG would be such that it could be executed to compute the semantics for every sentence of the original DCG. The motivation for our work comes from the observation that it is not easy to manually augment a CFG with semantic attributes to obtain a DCG because the task of building a correct and eecient DCG requires a fair amount of search, especially when the semantic representations involve quantiied terms, as in natural languages. Our proposed approach is based upon two key assumptions: (a) the semantic representation language is the simply-typed-calculus; and (b) the semantic representation of a sentence is a function (expressed in the typed-calculus) of the semantic representations of its parts (compositionality). With these assumptions we show how a higher-order DCG can be systematically constructed using a matching procedure for simply-typed-terms. We then show how to translate the constructed higher-order DCG into a rst-order DCG by a partial-execution procedure. We have applied our methodology to the synthesis of the semantics of a small query language, and we believe that this methodology could be a useful tool for generating natural query language front-ends for various applications. < This is an expanded version of the paper, \\Interactive Synthesis of Deenite-Clause Grammars,\" J.
Journal Article•
TL;DR: periodically time-variant grammars yield the rst example of a non-trivial equivalence of generating and accepting mode in the absence of appearance checkings.
Abstract: In this paper, we study the concept of accepting grammars within various forms of regulated grammars like programmed grammars, matrix (set) grammars, grammars with regular (set) control, periodically time-variant grammars as variants of grammars controlled by bi-coloured digraphs. We focus on their descriptive capacity. In this way, we continue our studies of accepting grammars 1, 2, 3, 11, 13, 14, 15]. Periodically time-variant grammars yield the rst example of a non-trivial equivalence of generating and accepting mode in the absence of appearance checkings. Supported by Deutsche Forschungsgemeinschaft grant DFG La 618/3-1.
TL;DR: A technique for forming a context free grammar for a document that has some kind of tagging-structural or typographical-but no concise description of the structure is available, based on ideas from machine learning.
Book•
01 Jan 1997
TL;DR: In this article, a grammatical approach to the LBA problem is presented, where the number of nonterminals in matrix grammars with leftmost derivations and the accepting power of finite automata over groups are investigated.
Abstract: A grammatical approach to the LBA problem.- Conditional context-free languages of finite index.- On the number of nonterminals in matrix grammars with leftmost derivations.- The accepting power of finite automata over groups.- Controlled fuzzy parallel rewriting.- On controlling rewriting by properties of strings and symbols.- Accepting array grammars with control mechanisms.- On restarting automata with rewriting.- Deterministic cooperating distributed grammar systems.- Grammar systems with counting derivation and dynamical priorities.- Characterization of RE using CD grammar systems with two registers and RL rules.- On cooperating distributed uniformly limited 0L systems.- Teams in grammar systems: Sub-context-free cases.- A note on the incomparability of the E0L family with certain families of languages generated by cooperating grammar systems.- Colonies as models of reactive systems.- Grammatical inference of colonies.- A grammar characterization of logarithmic-space computation.- On the computational complexity of context-free Parallel Communicating Grammar Systems.- Parallel communicating grammar systems with communication by signals.- PC grammar systems versus some non-context-free constructions from natural and artificial languages.- Grammar systems for the description of certain natural language facts.- Networks of parallel language processors.- A reduced distributed splicing system for RE languages.- On the generative capacity of splicing grammar systems.- Array splicing systems.- Two lower bounds on computational complexity of infinite words.- On ?-power languages.- Shuffle-like operations on ?-words.- Generalized Lindenmayerian algebraic systems.- The structure of the basic morphisms.- On mix operation.- On the complexity of iterated insertions.- The decidability of the generalized confluence problem for context-free languages.
01 Jan 1997
TL;DR: This work proves inclusion relations between the language families defined by grammars using, respectively, the weak and strong prefix- or equality-synchronized derivation mode, and can effectively decide whether the language generated by a weak BSCF grammar is empty.
Abstract: We consider context-free type block-synchronization grammars, BSCF grammars, where independent derivations can communicate using nested synchronization conditions. We prove inclusion relations between the language families defined by grammars using, respectively, the weak and strong prefix- or equality-synchronized derivation mode. In particular, the weak BSCF languages are strictly included in the family of strong BSCF languages for both the prefix- and equality-synchronized derivation mode. We can effectively decide whether the language generated by a weak BSCF grammar is empty.
09 Jun 1997
TL;DR: This research defines a block diagram grammar which generates block diagrams by means of subgraph rewriting of a graph grammar and develops a parser that parses a diagram in a bottom-up parallel method.
Abstract: A block diagram is a graphical model with which it is possible to concisely visualize a system structure and is widely used in control engineering and other fields. However, there are few studies that try to formulate a syntax of block diagrams. In this research, we define a block diagram grammar which generates block diagrams by means of subgraph rewriting of a graph grammar. It includes some context-sensitive productions and is very concise. We have also developed a parser based on this block diagram grammar that parses a diagram in a bottom-up parallel method. It decides whether a diagram is valid for the grammar or not, and returns a production instance sequence for a valid diagram.
01 Jan 1997
TL;DR: In Chapter 4 of [2], Book and Otto solve a number of word problems for monadic string-rewriting systems using an elegant automata-based technique using a uniform solution to several elementary problems on context-free languages.
Abstract: In Chapter 4 of [2], Book and Otto solve a number of word problems for monadic string-rewriting systems using an elegant automata-based technique. In this note we observe that the technique is also very interesting from a pedagogical point of view, since it provides a uniform solution to several elementary problems on context-free languages. We hope that Wilfried Brauer will consider these results for inclusion in the next edition of his textbook on automata theory [5].
TL;DR: Computation theory could be reconstructed without rewriting (and non-terminal symbols) and without any loss in power and some consequences for the future development of generative theory of natural language are obtained.
Abstract: Computation not only takes place in provoked contexts of scientific experimentation, but in natural circumstances too. We are going to approach computation in natural contexts. How the nature computes? Turing machines and Chomsky grammars are rewriting systems, and the same is true for Post, Thue, Markov, Lindenmayer and other classes of axiomatic systems. If, among the whole set of natural objects, we focus natural language description, we must say that major trends in contemporary linguistics look at syntax as a rewriting process. Is rewriting unavoidable in this case, does our mind work by rewriting, does the nature compute in this way? We shall attempt to defend that the answer could be negative. The arguments will come from computability theory as well as from linguistics. First we'll formally explain the former ones, then informally the latter ones. With regard to computability theory arguments, we will see that, using the operation of adjoining, a large generative capacity is obtained. This is the case with contextual grammars. It has recently been proved that each recursively enumerable language is the quotient by a regular language of a language generated by a contextual grammar of a particular form. Thus, adjoining (paste) and quotient (cut) lead to computational universality. Recursively enumerable languages can also be characterized as the quotient by a regular language of a language generated by an insertion grammar. The same result is obtained if we take the splicing operation, a formal model of the DNA recombination. This is again a cut-and-paste operation. On the basis of the proof of this result, several further characterizations of recursively enumerable languages have been obtained. Computability theory, then, could be reconstructed without rewriting (and non-terminal symbols) and without any loss in power. Our first aim will be to show some formal aspects of such reconstruction. Later, we'll try to obtain some consequences for the future development of generative theory of natural language.
Posted Content•
TL;DR: A grammar development system that includes a compiler of grammars (for parsing and generation) to abstract machine instructions, and an interpreter for the abstract machine language is presented, obtaining a unified, efficient platform for developing reversible Grammars.
Abstract: Contemporary linguistic theories (in particular, HPSG) are declarative in nature: they specify constraints on permissible structures, not how such structures are to be computed. Grammars designed under such theories are, therefore, suitable for both parsing and generation. However, practical implementations of such theories don't usually support bidirectional processing of grammars. We present a grammar development system that includes a compiler of grammars (for parsing and generation) to abstract machine instructions, and an interpreter for the abstract machine language. The generation compiler inverts input grammars (designed for parsing) to a form more suitable for generation. The compiled grammars are then executed by the interpreter using one control strategy, regardless of whether the grammar is the original or the inverted version. We thus obtain a unified, efficient platform for developing reversible grammars.
TL;DR: It is shown that dynamic LL( $k$) Parsers are as powerful as LR( $ k$) parsers, i.e. that they are capable to analyze every deterministic context-free language while using only one symbol of lookahead.
Abstract: A new class of context-free grammars, called dynamic context-free grammars, is introduced. These grammars have the ability to change the set of production rules dynamically during the derivation of some terminal string. The notion of LL(\(k\)) parsing is adapted to this grammar model. We show that dynamic LL(\(k\)) parsers are as powerful as LR(\(k\)) parsers, i.e. that they are capable to analyze every deterministic context-free language while using only one symbol of lookahead.
TL;DR: This investigation demonstrates that the family of recursively enumerable languages is characterized by six-nonterminal multi-sequential grammars.
Abstract: The present paper investigates the descriptional complexity of multi-sequential grammars with respect to the number of nonterminals. This investigation demonstrates that the family of recursively enumerable languages is characterized by six-nonterminal multi-sequential grammars.