Retour à l'index du GREYC

Séminaire Algorithmique

Site du CNRS

Séminaire Algorithmique

Le séminaire a lieu le mardi à 11 h 45 (sauf modification exceptionnelle), au campus Côte de Nacre, bâtiment Sciences 3, salle S3 351, 3ème étage.

Résumé du séminaire du Mardi 8 Avril 2003

Reconstructing Propositional Calculus in Database Semantics

par Roland Hausser (Universität Erlangen-Nürnberg)

This talk presents a reconstruction of propositional calculus as a simplified version of natural language used for communication. This requires a number of changes with respect to the traditional approach,

First, the method must be changed from the meta-language definitions of old logic to a declarative specification for computer software. Second, the realist ontology of old logic, treating meaning as a direct relation between sentences and the world (defined as a set-theoretic model) must be replaced by a functional system comprising an agent's cognitive operations. Third, the syntax of propositional calculus must be adapted to the time-linear nature of language. Fourth, the truth conditional semantics of propositional calculus must be integrated into the time-linear process of communication.

The latter task requires solutions to the following problems: First, whether an expression like p & ~p... is contradictory cannot be decided in a time-linear interpretation until the continuation, e.g., p & ~p v q..., is known; second, using truth conditions for checking consistency must avoid the SAT problem, which is known to be computationally intractable.

The reconstruction is presented as the declarative specification of a computer program, comprising (i) a data structure for storing formulas of propositional calculus as concatenated propositions, and (ii) LA-grammars for conceptualization, production, and interpretation. Written at a high level of abstraction, the reconstruction provides a comparison between the metalan\-guage-based approach of traditional logic and the procedural model of communication of database semantics.

Short vita : Professor Roland Hausser heads the Department of Computational Linguistics at the University Erlangen-Nürnberg in Germany. He has worked in formal semantics, grammar algorithms, and human-computer communication. Publications include several books, the latest foundations of Computational Linguistics, as well as papers in the AI Journal and the Journal of Theoretical Computer Science.

Campus Côte de Nacre, boulevard du Maréchal Juin
BP 5186
14032 Caen Cedex
FAX : +33 (0)2 31 56 73 30