The University of Edinburgh -
Division of Informatics
Forrest Hill & 80 South Bridge

MSc Thesis #9756

Title:Grelogic: a System for Translating and Solving Gre Logic Problems Written in English
Date:Sep 1997
Abstract:This thesis describes the system GRELogic developed during the spring and summer of 1997. GRELogic is both a Natural Language Processing (NLP) system and a Constraint Satisfaction Problem (CSP) solver. GRELogic accepts as input the English statement of a logic problem of the form specifically given in the Graduate Record Examination (GRE). This English problem is translated into a Prolog program - the Prolog program is essentially a reification of the meaning of the English problem into a CSP framework based on Prolog's Horn Clause logic. Translation from English to Prolog involves syntactic templates which directly correspond to constituents of an underlying semantic model of the statements, constraints, questions and answers of a typical GRE logic problem. A generate-and-test parsing strategy is used: first, we generate a syntactic skeleton using our semantic model as a guide, then we test whether this skeleton actually matches our English input. Once we find a matching skeleton, the generation process is repeated - this time to generate the Prolog correlative of the problem, which can then be executed to obtain the solutions. Preliminary testing indicates that GRELogic performs well on certain, well-defined sub-classes of the GRE logic problems; further development is necessary to overcome the context problem: the problem of creating and maintaining a large, consistent semantic model.

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