We consider the problem of computing the complete answer to a query when there is limited access to relations, i.e., when binding patterns require values to be speciied for certain attributes in order to retrieve data from a relation. This problem is common in information-integration systems , where heterogeneous sources have diverse and limited query capabilities. A query is stable if for any ...

We study the development of conjunctive keyword searchable scheme which enables one to search encrypted documents by using more than one keyword. The notion of conjunctive keyword searching was presented by Golle et al. in 2004. However, their security model was constructed in a symmetric-key setting which is not applicable for the overall applications in the reality. So Park et al. extended Go...

Parsing a long sentence is very difficult, since long sentences often have conjunctions which result in ambiguities. If the conjunctive s tructures existing in a long sentence can be analyzed correctly, ambiguities can be reduced greatly and a sentence can be parsed in a high successful rate. Since the prior par t and the posterior par t of a conjunctive s t ructure have a similar s t ructure v...

at Wien We perform a fundamental investigation of the complexity of conjunctive query evaluation from the perspective of parameterized complexity. We classify sets of boolean conjunctive queries according to the complexity of this problem. Previous work showed that a set of conjunctive queries is fixed-parameter tractable precisely when the set is equivalent to a set of queries having bounded t...

The DL-Lite family of Description Logics has been designed with the specific goal of allowing for answering complex queries (in particular, conjunctive queries) over ontologies with very large instance sets (ABoxes). So far, in DL-Lite systems, this goal has been actually achieved only for relatively simple (short) conjunctive queries. In this paper we present Presto, a new query answering tech...