(Copyright © 2000 Piero Scaruffi | Legal restrictions - Termini d'uso )
Focusing mainly on discourse analysis and historical natural language systems,
it contains seminal papers by Perrault, Hobbs, Grosz, Wilensky.
Perrault touches on mathematical properties of some popular linguistic formalisms: transformational grammars, Jerrold Kaplan's and Joan Bresnan's lexical-functional grammars, Gerald Gazdar's generalized phrase-structure grammar and Joshi's tree adjunction grammar.
Woods's 1970 paper describes a parser for non context-free languages: augmented transition networks, an extensions of recursive transition networks (directed graphs with labeled arcs and nodes) that have registers for storing partial parse trees or flagging features and conditions for testing registers to determine how to proceed. ATN's are equal in capacity to transformational grammars.
In 1980 Fernando Pereira and David Warren introduced a formalism (definite clause grammar) to define grammars based on Horn-clauses: grammar rules are written as logical formulas. Parsing is a form of theorem proving.
Coming to semantics, Drew McDermott's "No notation without denotation" played the role of a manifesto for systematic semantics: it is not only important that a syste be correct, it is also important that it can be understood.
Grosz thinks that dialogues exhibit a structure much like sentences and this structure affects the use of referring expressions. This "intentional" structure is characterized by a global focus of attention and a number of immediate foci of attention. Grosz analyzes the relationship between focus of attention and referring expressions. Grosz defines a focus space as that subset of the speaker's total knowledge which is relevant to a discourse segment. Several such spaces may be relevant at a time.
A number of papers cover the integration of natural language understanding and planning techniques (although Richard Fikes' STRIPS is not mentioned). Raymond Perrault and his associates model speech acts as operators and intentions as plans. Wilensky uses plan recognition for story understanding.
Historical natural language processing systems from the Seventies reviewed here include William Woods' LUNAR, Daniel Bobrow's GUS and Terry Winograd's SHRDLU.
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