scispace - formally typeset
Search or ask a question

Showing papers on "Context-sensitive grammar published in 1989"


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


09 May 1989
TL;DR: Several grammatical phenomena, such as coordination and extraposition, are treated mainly in a language-independent shell provided with the Slot Grammars system.
Abstract: Slot Grammar makes it easier to write practical, broad-coverage natural language grammars, for the following reasons. (a) The system has a lexicalist character; although there are grammar rules, they are fewer in number and simpler because analysis is largely data-driven through use of slots taken from lexical entries. (b) There is a modular treatment of different grammatical phenomena through different rule types, for instance rule types for expressing linear ordering constraints. This modularity also reduces the differences between the Slot Grammars of different languages. (c) Several grammatical phenomena, such as coordination and extraposition, are treated mainly in a language-independent shell provided with the system.

156 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


Patent
10 Jul 1989
TL;DR: In this paper, a compiler for register vector grammars is presented, which uses phase structure rules to generate strongly equivalent grammarmars in register vector grammar form, which can then be used to parse strings and trees.
Abstract: A context-free parsing algorithm employing register vector grammars provides fast parsing of natural languages A compiler for register vector grammars accepts input grammars as standard phase structure rules and generates strongly equivalent grammars in register vector grammar form By applying the context-free register vector grammar parsing algorithm to the resulting grammars, strings may be parsed and trees may be constructed in the same manner performed with phase structure grammar

57 citations


Proceedings Article
01 Jan 1989

50 citations


Journal ArticleDOI
TL;DR: These results are shown for graph Grammars with neighbourhood controlled embedding and with dynamic edge relabeling (eNCE grammars).
Abstract: A graph grammar is linear if it generates graphs with at most one nonterminal node. Linear graph grammars can simulate nonterminal bounded graph grammars (which generate graphs with a bounded number of nonterminal nodes) and derivation bounded graph grammars. If a linear graph language contains connected graphs of bounded degree only, then it is in NSPACE(log n ). These results are shown for graph grammars with neighbourhood controlled embedding and with dynamic edge relabeling (eNCE grammars).

46 citations


Journal ArticleDOI
TL;DR: A method for RAGs to sense the contexts of local shapes of a host array in a derivation is shown and it is proved that there is no context-free array grammar (and thus no RAG) which generates the set of all hollow upright rectangles.
Abstract: Regular array grammars (RAGs) are the lowest subclass in the Chomsky-like hierarchy of isometric array grammars. The left-hand side of each rewriting rule of RAGs has one nonterminal symbol and at most one "#" (a blank symbol). Therefore, the rewriting rules cannot sense contexts of non-# symbols. However, they can sense # as a kind of context. In this paper, we investigate this #-sensing ability. and study the language generating power of RAGs. Making good use of this ability, We show a method for RAGs to sense the contexts of local shapes of a host array in a derivation. Using this method, we give RAGs which generate the sets of all solid upright rectangles and all solid squares. On the other hand. it is proved that there is no context-free array grammar (and thus no RAG) which generates the set of all hollow upright rectangles.

29 citations


Book ChapterDOI
01 Jan 1989
TL;DR: This paper is a report on an ongoing work which is aiming at a general method which would help to considerably reduce the time necessary to develop a syntax-directed editor for any given diagram technique.
Abstract: This paper is a report on an ongoing work which started in 1981 and is aiming at a general method which would help to considerably reduce the time necessary to develop a syntax-directed editor for any given diagram technique. The main idea behind the approach is to represent diagrams by (formal) graphs whose nodes are enriched with attributes. Then, any manipulation of a diagram (typically the insertion of an arrow, a box, text, coloring, etc.) can be expressed in terms of the manipulation of its underlying attributed representation graph. The formal description of the manipulation is done by programmed attributed graph grammars.

23 citations


Journal ArticleDOI
TL;DR: A new class of grammars with derivation restrictions (similar to the matrix, conditional ones, etc.) is presented, where if a rule of a subset peculiar to P is used in a derivation then it is compulsory to use only productions of that particular subset as long as it is possible.
Abstract: In this article a new class of grammars with derivation restrictions (similar to the matrix, conditional ones, etc.) is presented. In this situation, if a rule of a subset peculiar to P is used in a derivation then it is compulsory to use only productions of that particular subset as long as it is possible. According to the Chomsky hierarchy, naturally attributed to the grammars the generative power of the modular grammars is studied (Section 2), a series of results being obtained as well as a normal form similar to Chomsky's normal one. The following two paragraphs deal with the closure properties—only for ℳ 2 and (proving that ℳ 2 is AFL) and also with decision problems connected with the modular grammars, using algorithmical proofs in general.

19 citations


Journal ArticleDOI
TL;DR: A syntactic model for generating sets of images, where an image can be viewed as an array over finite alphabet is defined, called image grammar, which can be considered as a generalization of classical Chomsky grammar.
Abstract: We define a syntactic model for generating sets of images, where an image can be viewed as an array over finite alphabet. This model is called image grammar. Image grammar can be considered as a generalization of classical Chomsky grammar. Then we study some combinatorial and language theoretical properties such as reduction, pumping lemmas, complexity measure, we give a strict infinite hierarchy. We also characterize these families in terms of deterministic substitutions and Chomsky languages.

16 citations


Proceedings ArticleDOI
01 Dec 1989
TL;DR: Some of the tradeoffs in learning power involved in making a well-defined version of a complexity restriction on the final grammar(s) converged to in the limit is that they all have small size.
Abstract: In Gold's influential language learning paradigm a learning machine converges in the limit to one correct grammar. In an attempt to improve Gold's paradigm, Case considered the question whether people might converge to vacillating between up to (some integer) n > 1 distinct, but equivalent, correct grammars. He showed that larger classes of languages can be algorithmically learned (in the limit) by converging to up to n +1 rather than up to n correct grammars. He also argued that, for “small” n > 1, it is plausible that people might sometimes converge to vacillating between up to n grammars. The insistence on small n was motivated by the consideration that, for “large” n , at least one of n grammars would be too large to fit in peoples' heads. This latter assumes, of course, that human brain storage is not magic, admitting of infinite regress, etc. Of course, even for Gold's n = 1 case, the single grammar converged to in the limit may be infeasibly large. An interesting complexity restriction to make, then, on the final grammar(s) converged to in the limit is that they all have small size. In this paper we study some of the tradeoffs in learning power involved in making a well-defined version of this restriction.

Proceedings Article
01 Jan 1989
TL;DR: In this article, a parallel evaluator for attribute grammars is presented, which can expose a significant degree of inherent parallelism, and thus further increase the evaluators performance.
Abstract: Examines the generation of parallel evaluators for attribute grammars, targeted to shared-memory MIMD computers. Evaluation-time overhead due to process scheduling and synchronization is reduced by detecting coarse-grain parallelism (as opposed to the naive one-process-per-node approach). As a means to more clearly expose inherent parallelism, it is shown how to automatically transform productions of the form X to Y X into list-productions of the form X to Y/sup +/. This transformation allows for many simplifications to be applied to the semantic rules, which can expose a significant degree of inherent parallelism, and thus further increase the evaluator's performance. Effectively, this constitutes an extension of the concept of attribute grammars to the level of abstract syntax. >

Proceedings ArticleDOI
26 Jun 1989
TL;DR: A more general class of unification Grammars is defined, which admits x-bar grammars while preserving the desirable properties of offline parsable grammARS.
Abstract: The offline parsable grammars apparently have enough formal power to describe human language, yet the parsing problem for these grammars is solvable. Unfortunately they exclude grammars that use x-bar theory - and these grammars have strong linguistic justification. We define a more general class of unification grammars, which admits x-bar grammars while preserving the desirable properties of offline parsable grammars.

Journal ArticleDOI
TL;DR: A two-dimensional grammar for generating all possible rectangles is presented and illustrated by examples and the time and space complexity analyses of this grammar together with a parallel context-free array grammar and a free grammar are presented.
Abstract: A two-dimensional grammar for generating all possible rectangles is presented and illustrated by examples. The time and space complexity analyses of this grammar together with a parallel context-free array grammar and a free grammar are also presented. Generating pictures using two-dimensional grammars appear to be a fertile field for further study. The study of two-dimensional grammars has useful applications in region filling. pattern recognition. robotics, pictorial information system design and related areas.

Journal ArticleDOI
TL;DR: In this article, it is shown that the class of languages generated by generalized context-free grammars (gcfg's) introduced by Pollard is exactly the same class of recursively enumerable sets.
Abstract: It is shown that the class of languages generated by generalized context-free grammars (gcfg's) introduced by Pollard is exactly the class of recursively enumerable sets. Next, a subclass of gcfg's called multiple context-free grammars (mcfg's) is introduced and it is shown that the class of languages generated by mcfg's properly contains the class of context-free languages and is properly contained in the class of context-sensitive languages. In mcfg's, it is possible to account for structures involving discontinuous constituents in a particularly simple manner. Such concepts as phrase structure and derivation tree in context-free grammars (cfg's) can be extended naturally in mcfg's. Furthermore, the class of languages generated by mcfg's enjoys the formal language-theoretic closure properties that the class of context-free languages does.

Journal ArticleDOI
TL;DR: This work investigates context-free grammars the rules of which can be used in a productive and in a reductive fashion, while the application of these rules is controlled by a regular language.
Abstract: We investigate context-free grammars the rules of which can be used in a productive and in a reductive fashion, while the application of these rules is controlled by a regular language. We distinguish several modes of derivation for this kind of grammar. The resulting language families (properly) extend the family of context-free languages. We establish some closure properties of these language families and some grammatical transformations which yield a few normal forms for this type of grammar. Finally, we consider some special cases (viz. the context-free grammar is linear or left-linear), and generalizations, in particular, the use of arbitrary rather than regular control languages.

01 Jan 1989
TL;DR: Initial and incremental evaluation algorithms are given, as well as a sample grammar allowing an editor for a small language to become an incremental interpreter for incremental reevaluation of programs after small changes to the code.
Abstract: Gated attribute grammars and error-tolerant unification expand upon the usual views of attribute grammars and unification. Normally, attribute grammars are constrained to be noncircular; gated attribute grammars allow fairly general circularities. Most unification algorithms do not behave well when given inconsistent input; the new unification paradigm proposed here not only tolerates inconsistencies but extracts information from them. The expanded views prove to be useful in interactive language-based programming environments. Generalized unification allows the environment to help the user find the sources of type errors in a program, while gated attribute grammars allow the environment to provide an interpreter for incremental reevaluation of programs after small changes to the code. The defining feature of gated attribute grammars is the appearance of a gate attribute (indicating where cycle evaluation should begin and end) within every cycle. Attributes are ordered by collapsing strongly connected components in the dependency graph and topologically sorting the result. The smaller dependency graph for each component (ignoring edges leading to the gate) can be recursively collapsed to provide further ordering. Use of the evaluation order defined in this manner allows gated attribute grammars to do without the restrictions on functions within a component needed by the other varieties of circular attribute grammars. Initial and incremental evaluation algorithms are given, as well as a sample grammar allowing an editor for a small language to become an incremental interpreter. Counting unification defines unique solutions to sets of input equations that contain conflicting type information. These solutions are derived from the potential variable constraints implied by the input equations. For each type variable, each branch (a portion of a constraint) is assigned a weight indicating the number of times the input set implied such a constraint. When the input equations are derived from the static analysis of a program, the relative branch weights for a conflicting variable give the overall pattern of uses of that variable and can direct attention to parts of the program that disagree with the majority of uses. A number of error-tolerant unification algorithms are presented.

Proceedings ArticleDOI
27 Mar 1989
TL;DR: The PSG-to-RVG compiler enables natural-language interface developers to design grammars at the phrase structure rule level, but execute them at the register vector grammar level, which maximizes both the understandability and efficiency of syntactic analysis.
Abstract: A procedure is described for compiling context-free phrase structure grammar (PSG) rules into equivalent context-free register vector grammars (RVG). The procedure makes use of finite-state automata (FSA) as an intermediate form, as well as standard FSA transformation and reduction algorithms to minimize the size of the resulting register vector grammars. An example using the syntax of English auxiliary verbs demonstrated the use of FSA in the translation process, and it was shown that such automata must be reduced to yield fewer RVG productions. It was also shown that an additional optimization phase is needed to further reduce the size and increase the efficiency of register vector grammars. The PSG-to-RVG compiler enables natural-language interface developers to design grammars at the phrase structure rule level, but execute them at the register vector grammar level. This approach maximizes both the understandability and efficiency of syntactic analysis. >

Journal ArticleDOI
TL;DR: A table-driven parsing algorithm that operates in quadratic time and an algorithm to produce the parsing table from a given grammar, the SPG class are included.

Journal ArticleDOI
TL;DR: A regular attribute grammar is an attribute grammar with an underlying context-free grammar which is right or left linear, and the restriction to regular underlying grammars restricts the possible dependencies between attributes; this permits efficient algorithms for attribute evaluation.
Abstract: A regular attribute grammar is an attribute grammar with an underlying context-free grammar which is right or left linear. The restriction to regular underlying grammars restricts the possible dependencies between attributes; this in turn permits efficient algorithms for attribute evaluation. An algorithm for performing attribute evaluation in parallel with a single scan of the input by a deterministic finite state machine is developed. Special cases of regular attribute grammars for which the algorithm uses very little space are identified. Several examples are included.

Journal ArticleDOI
TL;DR: This paper shows that if the authors require the functions to be shift-invariant and the rules to be of bounded diameter, then such coordinate grammars do have a useful hierarchy of types; in fact, when they require that their sentential forms always remain connected, they turn out to be equivalent to "isometric Grammars".
Abstract: In a "coordinate grammar", the rewriting rules replace sets of symbols having been given coordinates by sets of symbols whose coordinates are given functions of the coordinates of the original symbols. It was shown in 1972 that coordinate grammars are "too powerful"; even if the rules are all of finite-state types and the functions are all computable by finite transducers, the grammar has the power of a Turing machine. This paper shows that if we require the functions to be shift-invariant and the rules to be of bounded diameter, then such grammars do have a useful hierarchy of types; in fact, when we require that their sentential forms always remain connected, they turn out to be equivalent to "isometric grammars".

Journal ArticleDOI
Kai Salomaa1
TL;DR: This paper proves a pumping result for k-context-free languages and shows that the families of k-languages form a strict hierarchy with respect to k, and results showing the strictness of the hierarchy are presented.
Abstract: Languages generated by context-free grammars by rewriting always exactly k nonterminals simultaneouslyk ≥ 1, are called k-context-free languages. We prove a pumping result for k-context-free languages and using it show that the families of k-languages form a strict hierarchy with respect to k. The paper is divided into two parts. The main results showing the strictness of the hierarchy of k-languages are presented in Part 2. This first part contains definitions and preliminary results on derivation forests and k-schedules.

Journal ArticleDOI
TL;DR: Grammars for English and Japanese as they were employed in the KBMT-89 program are described and word order, coordination, subcategorization, morphological rules, rule ordering and bi-directional grammars are discussed.
Abstract: This paper describes the analysis and generation grammars for English and Japanese as they were employed in the KBMT-89 program. We discuss word order, coordination, subcategorization, morphological rules, rule ordering and bi-directional grammars.

Book ChapterDOI
11 Sep 1989
TL;DR: The main idea behind the approach is to represent diagrams by (formal) graphs whose nodes are enriched with attributes as mentioned in this paper, and any manipulation of a diagram (typically the insertion of an arrow, a box, text, coloring, etc.) can be expressed in terms of the manipulation of its underlying attributed representation graph.
Abstract: This paper is a report on an ongoing work which started in 1981 and is aiming at a general method which would help to considerably reduce the time necessary to develop a syntax-directed editor for any given diagram technique. The main idea behind the approach is to represent diagrams by (formal) graphs whose nodes are enriched with attributes. Then, any manipulation of a diagram (typically the insertion of an arrow, a box, text, coloring, etc.) can be expressed in terms of the manipulation of its underlying attributed representation graph. The formal description of the manipulation is done by programmed attributed graph grammars.


Journal ArticleDOI
TL;DR: A characterization of the LC(0) languages is given in terms of the simple deterministic languages and these classes of languages are compared with other classes of Languages, such as the LL(1) languages and the LR(0).


Journal ArticleDOI
TL;DR: This paper considered multiple context-free grammars (mcfg's) which inherit the basic properties of context free Grammars with generative capacity stronger than that of context-sensitive grammarm but weaker than context sensitive grammrs and showed that the complexity of the membership problem for languages generated by mcfg's is polynomial.
Abstract: This paper considers multiple context-free grammars (mcfg's) which inherit the basic properties of context-free grammars with generative capacity stronger than that of context-free grammars but weaker than that of context-sensitive grammars. It is shown that the time complexity of the membership problem for languages generated by mcfg's is polynomial. It is shown also that head grammars introduced by Pollard for describing the syntax of natural language correspond to a special subclass of mcfg's and, as a corollary, the time complexity of the membership problem for languages generated by head grammars is of order n6.* This is an improvement by one order of magnitude, compared with the result by Pollard.

Journal ArticleDOI
TL;DR: This paper shows that straightforward ratio estimators for the production probabilities of non-context-free unambiguous probabilistic grammars are maximum-likelihood estimators.
Abstract: This paper shows that straightforward ratio estimators for the production probabilities of non-context-free unambiguous probabilistic grammars are maximum-likelihood estimators These ratio estimates are obtained by analyzing the derivations of the strings in a random sample of strings taken from the language derived by the grammar

Journal ArticleDOI
TL;DR: A graph grammar called node-replacement graph grammar with path controlled embedding (nPCE grammars) which use a sequence of edges instead of the single edge to embed a newly replaced graph into the host graph is defined.
Abstract: We define a graph grammar called node-replacement graph grammar with path controlled embedding (nPCE grammars) which use a sequence of edges instead of the single edge to embed a newly replaced graph into the host graph, then show some relationships between two-dimensional "coordinate grammars" and nPCE grammars. We also suggest an extension of PCE grammars to describe "disconnected coordinate languages".