The standard approach for optimization of XPath queries by rewriting using views techniques consists in navigating inside a view’s output, thus allowing the usage of only one view in the rewritten query. Algorithms for richer classes of XPath rewritings, using intersection or joins on node identifiers, have been proposed, but they either lack completeness guarantees, or require additional infor...

Let XP(/, //, [ ]) be the fragment of XPath 1.0, consisting of queries that involve only the child and descendant axes, and predicates without disjunction or negation (and no wildcard nodetests); these queries can be represented as tree patterns. We consider the problem of rewriting a query Q using a materialized view V , where Q,V ∈ XP(/, //, [ ]). We present more efficient algorithms for the ...

We consider a subset of XPath expressions, called simple XPath expressions, which correspond to a class of conjunctive queries. We show that, in the absence of a DTD, each simple XPath expression has a unique minimal equivalent expression which can be found in polynomial time. We then consider D-equivalence, the equivalence of expressions with respect to the set of documents valid for a given D...

Dissemination systems are used to route information received from many publishers individually to multiple subscribers. The core of a dissemination system consists of an efficient filtering engine deciding what part of an incoming message goes to which recipient. Within this paper we are proposing a chunking framework of XML documents to speed up the filtering process for a set of registered su...

Publish-subscribe systems present the state of the art in information dissemination to multiple users. Such systems have evolved from simple topic-based to the current XML-enabled systems. Here, users pose complex queries (expressed in XPath) on the structure and content of the streaming documents. The parts of the documents that match the user queries are then returned to the users. This paper...