Objectives

The overall objective of the project is to propose new solutions for querying large scale multisource heterogeneous information, with two applications to web linked data and underwater archaeological surveys, where in both applications we face large data sets expressed in RDFs and OWL. The project is centered on three main requirements:

  • Processing multisource information: The fusion of multisource information systems is a huge and urgent task for the World-Wide Web applications, where pieces of information are often redundant, heterogeneous, imprecise,uncertain.. Besides, even if the information provided by each source is consistent it is rather unlikely that the union of all information will be consistent too. This project proposes adequate solutions to cope with inconsistent information.
  • Processing heterogeneous information: The information provided by multiple sources is often heterogeneous. This project focuses on web-based languages such as OWL2 family, more precisely, tractable sublanguages dedicated to query answering, OWL2 EL, OWL2 QL OWL2 RL. Nevertheless, currently available languages do not allow for satisfactory uncertainty and inconsistency handling.
  • Performing large scale reasoning: Effective implementation of huge amount of heterogeneous multi-source items of information requires suitable tools. The Answer Set Programming paradigm (ASP), with the development of more and more efficient solvers, compelled recognition in the last decade as an efficient reasoning tool but also as a very expressive formalism. However, most of the solvers are mainly dedicated to propositional logic, while an extension of ASP is required for querying ontological knowledge represented in OWL2 sublanguages.

The main objective of this project is to propose:

  1. Extensions of standard ASP for representing OWL2 tractable sublanguages in order to provide a common representation of the knowledge provided by multiple sources, allowing to deal with inconsistencies, exceptions and uncertainties, while staying compatible with efficiently querying knowledge bases with large amounts of data.
  2. New operations for merging information represented in extended ASP, of various reliability and quality with or without uncertainty, according to the commensurability assumption or not. Besides efficient algorithms will be proposed for handling conflicts in extended ASP programs.
  3. The identification of subclasses of this extended ASP allowing for an implementation of efficient query answering mechanisms moreover able to order and compute the most relevant answers.
  4. An efficient implementation of scalable inconsistency handling, fusion operations, defeasible reasoning like exception handling, possibilistic uncertainty and query answering for multiple knowledge bases. The design of a prototype reasoning system capable of managing fusion operations, solving conflicts and query answering for multiple knowledge bases. This prototype will be evaluated on two applications :
    • Web data integration, the Linked Data issue, which consists of interconnecting web data sources (bibliographic catalogues in our case) in collaboration with ABES (http://www.abes.fr).
    • Querying information stemming from 3D surveys for helping archaeologists to study underwater sites, in the following of the European VENUS project (http://sudek.esil.univmed.fr/venus/)
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