Web and Semantic Web Query Languages

A number of techniques have been developed to facilitate powerful data retrieval on the Web and Semantic Web. Three categories of Web query languages can be distinguished, according to the format of the data they can retrieve: XML, RDF and Topic Maps. This article introduces the spectrum of languages falling into these categories and summarises their salient aspects. The languages are introduced using common sample data and query types. Key aspects of the query languages considered are stressed in a conclusion

Use and Analysis of Expected Similarity of Semantic Web Ontological Annotations

This dissertation studied various means of calculating similarity in the annotations of web pages compared to the similarity of the document text. A software tool, named Semantic Web Analysis of Similarity (SW AS), was developed and utilized to perform the analysis of similarity in annotated documents published from the first three years of the International Semantic Web Conference. Rules concerning the ontological concepts of the documents were specified and these rules as well as other parameters were varied to determine the effect on overall similarity measures. Traditional measures of similarity as well as enhanced measures of similarity proposed for this study were evaluated. A proposal was made concerning use of similarity measures to evaluate the consistency of semantic annotation for documents published through a Semantic Web portal

Automatic Extraction of Semantically-Meaningful Information from the Web.

The semantic Web will bring meaning to the Internet,making it possible for web agents to understand the information it contains. However,curren t trends seem to suggest that the semantic web is not likely to be adopted in the forthcoming years. In this sense,meaningful information extraction from the web becomes a handicap for web agents. In this article,w e present a framework for automatic extraction of semantically-meaningful information from the current web. Separating the extraction process from the business logic of an agent enhances modularity,adaptabilit y,and maintainability. Our approach is novel in that it combines different technologies to extract information,surf the web and automatically adapt to web changes.Comisión Interministerial de Ciencia y Tecnología TIC2000-1106-C02-0

Survey over Existing Query and Transformation Languages

A widely acknowledged obstacle for realizing the vision of the Semantic Web is the inability of many current Semantic Web approaches to cope with data available in such diverging representation formalisms as XML, RDF, or Topic Maps. A common query language is the first step to allow transparent access to data in any of these formats. To further the understanding of the requirements and approaches proposed for query languages in the conventional as well as the Semantic Web, this report surveys a large number of query languages for accessing XML, RDF, or Topic Maps. This is the first systematic survey to consider query languages from all these areas. From the detailed survey of these query languages, a common classification scheme is derived that is useful for understanding and differentiating languages within and among all three areas

A abordagem POESIA para a integração de dados e serviços na Web semantica

Orientador: Claudia Bauzer MedeirosTese (doutorado) - Universidade Estadual de Campinas, Instituto de ComputaçãoResumo: POESIA (Processes for Open-Ended Systems for lnformation Analysis), a abordagem proposta neste trabalho, visa a construção de processos complexos envolvendo integração e análise de dados de diversas fontes, particularmente em aplicações científicas. A abordagem é centrada em dois tipos de mecanismos da Web semântica: workflows científicos, para especificar e compor serviços Web; e ontologias de domínio, para viabilizar a interoperabilidade e o gerenciamento semânticos dos dados e processos. As principais contribuições desta tese são: (i) um arcabouço teórico para a descrição, localização e composição de dados e serviços na Web, com regras para verificar a consistência semântica de composições desses recursos; (ii) métodos baseados em ontologias de domínio para auxiliar a integração de dados e estimar a proveniência de dados em processos cooperativos na Web; (iii) implementação e validação parcial das propostas, em urna aplicação real no domínio de planejamento agrícola, analisando os benefícios e as limitações de eficiência e escalabilidade da tecnologia atual da Web semântica, face a grandes volumes de dadosAbstract: POESIA (Processes for Open-Ended Systems for Information Analysis), the approach proposed in this work, supports the construction of complex processes that involve the integration and analysis of data from several sources, particularly in scientific applications. This approach is centered in two types of semantic Web mechanisms: scientific workflows, to specify and compose Web services; and domain ontologies, to enable semantic interoperability and management of data and processes. The main contributions of this thesis are: (i) a theoretical framework to describe, discover and compose data and services on the Web, inc1uding mIes to check the semantic consistency of resource compositions; (ii) ontology-based methods to help data integration and estimate data provenance in cooperative processes on the Web; (iii) partial implementation and validation of the proposal, in a real application for the domain of agricultural planning, analyzing the benefits and scalability problems of the current semantic Web technology, when faced with large volumes of dataDoutoradoCiência da ComputaçãoDoutor em Ciência da Computaçã

Using Ontologies to Improve Answer Quality in Databases

One of the known shortcomings of relational and XML databases is that they overlook the semantics of terms when answering queries. Ontologies constitute a useful tool to convey the semantics of terms in databases. However, the problem of effectively using semantic information from ontologies is challenging. We first address this problem for relational databases by the notion of an ontology extended relation (OER). An OER contains an ordinary relation as well as an associated ontology that conveys semantic meaning about the terms being used. We then extend the relational algebra to query OERs. We build a prototype for the OER model and show that the system scales to handle large datasets. We then propose the concept of a similarity enhanced ontology (SEO), which brings a notion of similarity to a graph ontology. We extend TAX, one of the best known algebras for XML databases, with SEOs. The result is our TOSS system that provides a much higher answer quality than TAX does alone. We experimentally evaluate the TOSS system on the DBLP and SIGMOD bibliographic databases and show that TOSS has acceptable performance. These two projects have involved ontology integration for supporting semantic queries across heterogeneous databases. We show how to efficiently compute the canonical witness to the integrability of graph ontologies given a set of interoperation constraints. We have also developed a polynomial algorithm to compute a minimal witness to the integrability of RDF ontologies under a set of Horn clauses and negative constraints, and experimentally show that our algorithm works very well on real-life ontologies and scales to massive ontologies. We finally present our work on ontology-based similarity measures for finding relationships between ontologies and searching similar objects. These measures are applicable to practical classification systems, where ontologies can be DAG-structured, objects can be labeled with multiple terms, and ambiguity can be introduced by an evolving ontology or classifiers with imperfect knowledge. The experiments on a bioinformatics application show that our measures outperformed previous approaches

A concept-based retrieval tool: The cooperative Web

IADIS International Conference WWW/Internet 2002, Lisboa (Portugal)The Web is a colossal document repository that is nowadays processed by humans only. Machines' role is limited to transmission and layout processing, barely being able to do something else with contents of documents. Therefore, information retrieval in the current Web is a difficult task where many results provide little relevance. The Semantic Web tries to solve this and other problems by means of new technologies to build ontologies and to annotate semantically the documents. Many of the ontological initiatives try to achieve automatic ontologies construction and semantic annotation. However, such tasks require close human supervision. In addition to that, although the Semantic Web can be very useful to retrieve information from semistructured repositories from e-business, digital libraries and corporate intranets, it is difficult to turn it into a shell over the Web as a whole because the Web size and heterogeneity hinder the development of ontologies to satisfy any conceivable query. We propose a different, although complementary, approach to the Semantic Web called the Cooperative Web. With this approach it would be possible to extract semantics from the Web providing better information retrieval mechanisms without the need of ontological artifacts

Ontological Engineering: What are Ontologies and How Can We Build Them?

Ontologies are formal, explicit specifications of shared conceptualizations. There is much literature on what they are, how they can be engineered and where they can be used inside applications. All these literature can be grouped under the term “Ontological Engineering,” which is defined as the set of activities that concern the ontology development process, the ontology lifecycle, the principles, methods and methodologies for building ontologies, and the tool suites and languages that support them. In this chapter we provide an overview of Ontological Engineering, describing the current trends, issues and problem