Concept-based querying in mediator systems

Sattler, Kai-Uwe; Geist, Ingolf; Schallehn, Eike

doi:10.1007/s00778-003-0118-9

Cited by 22 publications

(15 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We are particularly concerned with the DL fragment of OWL, where classes, properties, and individuals are disjoint sets. To address the need for querying over information modeled as ontologies, a number of RDF/OWL query languages have been developed [2][10] [13], and the W3C has published a Last Call Working Draft for an RDF query language and protocol called SPARQL [11]. SPARQL is a declarative language, designed specifically to obtain information from RDF graphs.…”

Section: Queries and Query Patternsmentioning

confidence: 99%

See 1 more Smart Citation

Cardinality estimation for the optimization of queries on ontologies

2007

View full text Add to dashboard Cite

An effective, accurate algorithm for cardinality estimation of queries on ontology models of data is presented. The algorithm relies on the decomposition of queries into query pattern paths, where each path produces a set of values for each variable within the result form of the query. In order to estimate the total number of result set parameters for each path, a set of statistics is compiled on the properties of the ontology. Experimental analysis has shown that the algorithm produces estimates with high accuracy and with high correlation to actual values. Thus, this algorithm can be used as the cornerstone of an effective optimization strategy for queries on diverse, heterogeneous data sources modeled as ontologies.

show abstract

Section: Queries and Query Patternsmentioning

confidence: 99%

“…To estimate cardinalities based on these structural constraints, statistics are kept on the properties comprising the data model. (13) where abs is the absolute value. The standard deviation :(p i ,p j ) of the dependent property cardinality is given by the positive square root of the variance.…”

Section: Estimation Over Structural Query Pattern Pathsmentioning

confidence: 99%

Cardinality estimation for the optimization of queries on ontologies

2007

View full text Add to dashboard Cite

show abstract

“…Search by important associations to some related concepts or user context or profile has been addressed by the emerging concept or knowledge based querying approaches [12,13]. In general, these approaches make use of domain specific ontologies and semantic annotations in order to augment and improve query semantics either interactively [3] or as performed by the system [12,13] for different purposes, e.g., search engines and information retrieval [13], and mediation across heterogeneous data sources [12].…”

Section: Literature Reviewmentioning

confidence: 99%

“…In general, these approaches make use of domain specific ontologies and semantic annotations in order to augment and improve query semantics either interactively [3] or as performed by the system [12,13] for different purposes, e.g., search engines and information retrieval [13], and mediation across heterogeneous data sources [12]. However, they mostly rely on intelligent techniques and knowledgebased approaches for mappings across concepts and query expansion.…”

Section: Literature Reviewmentioning

confidence: 99%

Cross-Lingual Information Retrieval and Delivery Using Community Mobile Networks

Raghunathan

Sugumaran

Kapetanios

2007

2006 1st International Conference on Digital Information Management

View full text Add to dashboard Cite

“…Because of the large number of application scenarios related work will concentrate on implementations and systems. In [24] a concept-based data integration system is described which was developed to integrate data about cultural assets. Although RDF ontologies are used to describe these assets, query processing is based on XML and a special query language called CQuery.…”

Section: Related Workmentioning

confidence: 99%

A Semantic Web Middleware for Virtual Data Integration on the Web

Langegger

Wöß

Blöchl

Lecture Notes in Computer Science

View full text Add to dashboard Cite

Abstract. In this contribution a system is presented, which provides access to distributed data sources using Semantic Web technology. While it was primarily designed for data sharing and scientific collaboration, it is regarded as a base technology useful for many other Semantic Web applications. The proposed system allows to retrieve data using SPARQL queries, data sources can register and abandon freely, and all RDF Schema or OWL vocabularies can be used to describe their data, as long as they are accessible on the Web. Data heterogeneity is addressed by RDF-wrappers like D2R-Server placed on top of local information systems. A query does not directly refer to actual endpoints, instead it contains graph patterns adhering to a virtual data set. A mediator finally pulls and joins RDF data from different endpoints providing a transparent on-the-fly view to the end-user.The SPARQL protocol has been defined to enable systematic data access to remote endpoints. However, remote SPARQL queries require the explicit notion of endpoint URIs. The presented system allows users to execute queries without the need to specify target endpoints. Additionally, it is possible to execute join and union operations across different remote endpoints. The optimization of such distributed operations is a key factor concerning the performance of the overall system. Therefore, proven concepts from database research can be applied.

show abstract

Concept-based querying in mediator systems

Cited by 22 publications

References 19 publications

Cardinality estimation for the optimization of queries on ontologies

Cardinality estimation for the optimization of queries on ontologies

Cross-Lingual Information Retrieval and Delivery Using Community Mobile Networks

A Semantic Web Middleware for Virtual Data Integration on the Web

Contact Info

Product

Resources

About