Using semantics to enhance query reformulation in dynamic distributed environments

AUTOR(ES)

Damires Yluska de Souza Fernandes

DATA DE PUBLICAÇÃO

2009

RESUMO

Query answering has been addressed as a key issue in dynamic distributed environments. An important step in this process is reformulating a query posed at a peer into a new query expressed in terms of a target peer, considering existing correspondences between them. Traditional approaches usually aim at reformulating queries by means of equivalence correspondences. However, concepts from a source peer do not always have exact corresponding concepts in a target one, what may result in an empty reformulation and, possibly, no answer to users. In this case, if users define that it is relevant for them to receive semantically related answers, it may be better to produce an enriched query reformulation and, consequently, close answers than no answer at all. In this work, we propose a semantic-based approach, named SemRef, which brings together both query enrichment and query reformulation techniques in order to provide users with a set of expanded answers. Exact and enriched query reformulations are produced as a means to obtain this set of answers. To this end, we make use of semantics which is mainly acquired from a set of semantic correspondences that extend the ones commonly found. Examples of such unusual correspondences are closeness and disjointness. Furthermore, we take into account the context of the user, of the query and of the environment as a way to enhance the overall process and to deal with information that can only be acquired on the fly. We formalize our definitions using ALC Description Logics and present the algorithm underlying our approach with properties that guarantee its soundness and completeness. We implement the SemRef algorithm within a query submission and execution module for a Peer Data Management System (PDMS). We provide examples illustrating its usage and advantages. Finally, we present the experimentation we have done with SemRef and the obtained results

ASSUNTO(S)

ambientes distribuÃdos e dinÃmicos semÃntica ciencia da computacao dynamic distributed environments reformulaÃÃo de consulta context semantics query reformulation banco de dados

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