Overall Objectives
Application Domains
New Software and Platforms
Bilateral Contracts and Grants with Industry
Partnerships and Cooperations
Bibliography
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Section: New Results

Data Integration and Schema Validation

Data integration requires knowledge about the structure of the various data. Such a structure is usually described by schemas. While for relational databases, schemas are hard-coded, this is not the case for many other formats. In XML for instance, several schema formalisms exists, such as DTD, XML Schema or Schematron. The Links Project-Team investigate the problem of defining schemas and use them to data, in particular for RDF and JSON Formats.

Also, J. Dusart develops under the supervision of I. Boneva and S. Staworko the software ShEx Validator so as to foster the practical usage of ShEx. It is also worth noting that ShEx is now being adopted by several institutions such as WikiData.

Aggregates

Aggregation refers to computations that are alien to mere logical data manipulation (e.g. such as in relational algebra). Typically, aggregation means counting the number of answers, or performing other kinds of statistics. We have a slightly larger understanding as we may also include enumerating all answers with a small delay. Aggregation algorithms are generally subtle as they in most cases avoid the explicit generation of the whole set of answers. We study aggregation problems within the ANR project Aggreg coordinated by Niehren.

In the same spirit, Capelli et al. (in a joint work with Mengel from the CNRS in Lens) showed at STACS [7] a new knowledge compilation procedure which allows a polynomial algorithm to test the satisfiability quantified Boolean formulas with bounded tree width. In Theory of Computing Systems, [25], Capelli also gave a taxonomy of results according to various restrictions of tree-width of graphs.

Also, in Theory of Computing Systems, [25], Capelli gave a taxonomy of results according to various restrictions of tree-width of graphs.

Finally, in an article in JCSS [14], F. Capelli (with Bergougnoux and Kanté from Bordeaux and Clermont-Ferrand) propose an algorithm for counting the number of transversals (i.e. subset of nodes intersecting all hyperedges) in some hypergraphs.