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We present the whole querying process of our ontologybased data integration proposal, that we call Semantic Mediator. The global schema (a TBox) is composed of the source schemas (also Tboxes) and a taxonomy, which links the sources to each other. The querying process is based on the global-schema's structure and consists of three steps: global query rewriting, source querying and global answer building. We describe the overall distributed system and the query-rewriting algorithm. Then we present an application of such a semantic mediation, the Personae project, which is for enabling historians to share their prosopographic data from the Middle Ages and the Renaissance.

We present an algorithm for the correction of an XML document with respect to schema constraints expressed as a DTD. Given a well-formed XML document t seen as a tree, a schema S and a non negative threshold th, the algorithm finds every tree t ′ valid with respect to S such that the edit distance between t and t ′ is no higher than th. The algorithm is based on a recursive exploration of the finite-state automata representing structural constraints imposed by the schema, as well as on the construction of an edit distance matrix storing edit sequences leading to correction candidate trees. We prove the termination, correctness and completeness of the algorithm, as well as its exponential time complexity. We also perform experimental tests on real-life XML data showing the influence of various input parameters on the execution time and on the number of solutions found. The algorithm's implementation demonstrates polynomial rather than exponential behavior. It has been made public under the GNU LGPL v3 license. As we show in our in-depth discussion of the related work, this is the first full-fledged study of the document-to-schema correction problem.

Abstract. We consider the incremental validation of updates on XML docu-