Browse Prior Art Database

Conditional Descriptions in Functional Unification Grammar

IP.com Disclosure Number: IPCOM000128678D
Original Publication Date: 1987-Dec-31
Included in the Prior Art Database: 2005-Sep-16
Document File: 11 page(s) / 37K

Publishing Venue

Software Patent Institute

Related People

Robert Kasper: AUTHOR [+3]

Abstract

Often, a grammatical description only applies to a linguistic object when that object has certain features. Such conditional descriptions can be indirectly modeled in Kay's Functional Unification Grammar (FUG) with functional descriptions that are embedded within disjunctive alternatives. An extension to FUG is proposed that allows for a direct representation of conditional descriptions: This extension has been used to model the input conditions on the systems of systemic grammar. Conditional descriptions are formally defined in terms of logical implication and negation. This formal definition enables the use of conditional descriptions as a general rotational extension to any of the unification-based grammar representation, systems currently used in computational linguistics.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 10% of the total text.

Page 1 of 11

THIS DOCUMENT IS AN APPROXIMATE REPRESENTATION OF THE ORIGINAL.

Conditional Descriptions in Functional Unification Grammar

Robert Kasper

ISI Research Report ISIIRR-87-191 November 1987 University of Southern California I I INFORMATION SCIENCES INSTITUTE 213/822-1511

4676 Admiralty Way/Marina del Rey/California 90292-6695

This research is supported by the Air Force Office of Scientific Research under Contract No. F49620-87-C-0005. Views and conclusions contained in this report are the author's and should not be interpreted as representing the official opinion or policy of AFOSR,the U S Government, or any person or agency connected with them. Conditional Descriptions in Functional Unification Grammar

Robert Kasper USC ~ Information Sciences Institute

Abstract

Often, a grammatical description only applies to a linguistic object when that object has certain features. Such conditional descriptions can be indirectly modeled in Kay's Functional Unification Grammar (FUG) with functional descriptions that are embedded within disjunctive alternatives. An extension to FUG is proposed that allows for a direct representation of conditional descriptions: This extension has been used to model the input conditions on the systems of systemic grammar. Conditional descriptions are formally defined in terms of logical implication and negation. This formal definition enables the use of conditional descriptions as a general rotational extension to any of the unification-based grammar representation, systems currently used in computational linguistics.

1 Introduction

Functional Unification Grammar (61 (FUG) and other grammatical formalisms that use feature structures and unification provide a general basis for the declarative representation of natural language grammars. These formalisms provide a rich information structure that can express a wide variety of linguistic generalizations. A particularly attractive feature of these grammars is that they are readable by linguists and are also subject to interpretation by general computational tools, such as those for parsing or generating text. In order to exploit some of the computational tools available with unification grammars, we have developed a mapping from systemic grammars (11 into FUG notation. This mapping has been used as the first step in creating a general parsing method for systemic grammars (2). The experience of translating systemic grammars into FUG has shown several ways in which the rotational resources of FUG may be improved. In particular, FUG has limited rotational resources for expressing conditional information. This report describes how FUG has been enhanced by the addition of conditional de-scriptions, building on research that has already been reported [2,3,4). In previous work, conditional descriptions were described informally as selection conditions. Selection.condi-tions were formulated specifically to facilitate the modeling of systemic grammar, but the notion of conditional...