CHR Grammars

A grammar formalism based upon CHR is proposed analogously to the way Definite Clause Grammars are defined and implemented on top of Prolog. These grammars execute as robust bottom-up parsers with an inherent treatment of ambiguity and a high flexibility to model various linguistic phenomena. The formalism extends previous logic programming based grammars with a form of context-sensitive rules and the possibility to include extra-grammatical hypotheses in both head and body of grammar rules. Among the applications are straightforward implementations of Assumption Grammars and abduction under integrity constraints for language analysis. CHR grammars appear as a powerful tool for specification and implementation of language processors and may be proposed as a new standard for bottom-up grammars in logic programming. To appear in Theory and Practice of Logic Programming (TPLP), 2005Comment: 36 pp. To appear in TPLP, 200

New and improved : Linda in Java

This paper discusses the current resurgence of interest in the Linda coordination language for parallel and distributed programming. Particularly in the Java field, there have been a number of developments over the past few years. These developments are summarised together with the advantages of using Linda for programming concurrent systems. Some problems with the basic Linda approach are also discussed and a novel solution to these is presented. The power and flexibility of the proposed extensions to the Linda programming model are illustrated by considering a number of example applications, including a detailed case study of visual language parsing

Symbol–Relation Grammars: A Formalism for Graphical Languages

AbstractA common approach to the formal description of pictorial and visual languages makes use of formal grammars and rewriting mechanisms. The present paper is concerned with the formalism of Symbol–Relation Grammars (SR grammars, for short). Each sentence in an SR language is composed of a set of symbol occurrences representing visual elementary objects, which are related through a set of binary relational items. The main feature of SR grammars is the uniform way they use context-free productions to rewrite symbol occurrences as well as relation items. The clearness and uniformity of the derivation process for SR grammars allow the extension of well-established techniques of syntactic and semantic analysis to the case of SR grammars. The paper provides an accurate analysis of the derivation mechanism and the expressive power of the SR formalism. This is necessary to fully exploit the capabilities of the model. The most meaningful features of SR grammars as well as their generative power are compared with those of well-known graph grammar families. In spite of their structural simplicity, variations of SR grammars have a generative power comparable with that of expressive classes of graph grammars, such as the edNCE and the N-edNCE classes

Acquiring Word-Meaning Mappings for Natural Language Interfaces

This paper focuses on a system, WOLFIE (WOrd Learning From Interpreted Examples), that acquires a semantic lexicon from a corpus of sentences paired with semantic representations. The lexicon learned consists of phrases paired with meaning representations. WOLFIE is part of an integrated system that learns to transform sentences into representations such as logical database queries. Experimental results are presented demonstrating WOLFIE's ability to learn useful lexicons for a database interface in four different natural languages. The usefulness of the lexicons learned by WOLFIE are compared to those acquired by a similar system, with results favorable to WOLFIE. A second set of experiments demonstrates WOLFIE's ability to scale to larger and more difficult, albeit artificially generated, corpora. In natural language acquisition, it is difficult to gather the annotated data needed for supervised learning; however, unannotated data is fairly plentiful. Active learning methods attempt to select for annotation and training only the most informative examples, and therefore are potentially very useful in natural language applications. However, most results to date for active learning have only considered standard classification tasks. To reduce annotation effort while maintaining accuracy, we apply active learning to semantic lexicons. We show that active learning can significantly reduce the number of annotated examples required to achieve a given level of performance

A Graphical User Interface for Designing Graph Grammars

Graph grammar has been widely applied in many scientific areas. However, designing graph grammar is very challenging for users without strong computer science background. This paper presents a graphical user interface (GUI) for designing graph grammars following an edge-based context-sensitive graph grammar formalism, EGG. This GUI significantly eases graph grammar design, especially for users unfamiliar with the grammar format

Multiset-Based Knowledge Representation for the Assessment and Optimization of Large-Scale Sociotechnical Systems

This chapter is dedicated to a new knowledge representation model, providing convergence of classical operations research and modern knowledge engineering. Kernel of the introduced model is the recursively generated multisets, selected according to the predefined restrictions and optimization criteria. Sets of multisets are described by the so-called multiset grammars (MGs), being projection of a conceptual background of well-known string-generating grammars on the multisets universum. Syntax and semantics of MGs and their practice-oriented development—unitary multiset grammars and metagrammars—are considered

Reusing Semantics in Visual Editors: A Case for Reference Attribute Grammars

The semantic formalism reference attribute grammars (RAGs) allows graphs to be superimposed on abstract syntax trees. This paper investigates how RAGs can be used to model visual languages, with a case study of a control language that also has a textual syntax. The language contains blocks on which a total execution order is defined based on connections and layout information. One strength of RAGs is reusability, and we demonstrate this by reusing the definition of the execution order in the visual editor to provide semantic feedback to the user

Design, construction, and application of a generic visual language generation environment

2000-2001 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Formalizing graphical notations

The thesis describes research into graphical notations for software engineering, with a principal interest in ways of formalizing them. The research seeks to provide a theoretical basis that will help in designing both notations and the software tools that process them. The work starts from a survey of literature on notation, followed by a review of techniques for formal description and for computational handling of notations. The survey concentrates on collecting views of the benefits and the problems attending notation use in software development; the review covers picture description languages, grammars and tools such as generic editors and visual programming environments. The main problem of notation is found to be a lack of any coherent, rigorous description methods. The current approaches to this problem are analysed as lacking in consensus on syntax specification and also lacking a clear focus on a defined concept of notated expression. To address these deficiencies, the thesis embarks upon an exploration of serniotic, linguistic and logical theory; this culminates in a proposed formalization of serniosis in notations, using categorial model theory as a mathematical foundation. An argument about the structure of sign systems leads to an analysis of notation into a layered system of tractable theories, spanning the gap between expressive pictorial medium and subject domain. This notion of 'tectonic' theory aims to treat both diagrams and formulae together. The research gives details of how syntactic structure can be sketched in a mathematical sense, with examples applying to software development diagrams, offering a new solution to the problem of notation specification. Based on these methods, the thesis discusses directions for resolving the harder problems of supporting notation design, processing and computer-aided generic editing. A number of future research areas are thereby opened up. For practical trial of the ideas, the work proceeds to the development and partial implementation of a system to aid the design of notations and editors. Finally the thesis is evaluated as a contribution to theory in an area which has not attracted a standard approach