Yuangui Lei

SemSearch: a search engine for the semantic web

Existing semantic search tools have been primarily designed to enhance the performance of traditional search technologies but with little support for ordinary end users who are not necessarily familiar with domain specific semantic data, ontologies, or SQL-like query languages. This paper presents SemSearch, a search engine, which pays special attention to this issue by providing several means to hide the complexity of semantic search from end users and thus make it easy to use and effective.

The usability of semantic search tools: A review

The goal of semantic search is to improve on traditional search methods by exploiting the semantic metadata. In this paper, we argue that supporting iterative and exploratory search modes is important to the usability of all search systems. We also identify the types of semantic queries the users need to make, the issues concerning the search environment and the problems that are intrinsic to semantic search in particular. We then review the four modes of user interaction in existing semantic search systems, namely keyword-based, form-based, view-based and natural language-based systems. Future development should focus on multimodal search systems, which exploit the advantages of more than one mode of interaction, and on developing the search systems that can search heterogeneous semantic metadata on the open semantic Web.

An Ontology-Driven Approach to Web Site Generation and Maintenance

Building and maintaining a data-intensive web site is costly and time-consuming and a number of approaches have addressed this problem using a model-based methodology. This paper presents IIPS (Intelligent Information Presentation System), a system that uses an ontology-driven approach to site generation and management. IIPS provides a suite of visual tools, which make it possible to model a data-intensive web site at a conceptual level, using site, interface and domain ontologies. As a result, the site designer can focus on the conceptual structure of the target web site and associated resources, independently of its realization. IIPS also provides explicit mapping mechanisms, which make it possible to generate quickly site implementations from the conceptual model. IIPS improves over existing model-based approaches to web design, by providing knowledge-level support for all aspects of web design, including site and resource specification, presentation and domain data.

A framework for evaluating semantic metadata

Because poor quality semantic metadata can destroy the effectiveness of semantic web technology by hampering applications from producing accurate results, it is important to have frameworks that support their evaluation. However, there is no such framework developedto date. In this context, we proposed i) an evaluation reference model, SemRef, which sketches some fundamental principles for evaluating semantic metadata, and ii) an evaluation framework, SemEval, which provides a set of instruments to support the detection of quality problems and the collection of quality metrics for these problems. A preliminary case study of SemEval shows encouraging results.

An infrastructure for acquiring high quality semantic metadata

Because metadata that underlies semantic web applications is gathered from distributed and heterogeneous data sources, it is important to ensure its quality (i.e., reduce duplicates, spelling errors, ambiguities). However, current infrastructures that acquire and integrate semantic data have only marginally addressed the issue of metadata quality. In this paper we present our metadata acquisition infrastructure, ASDI, which pays special attention to ensuring that high quality metadata is derived. Central to the architecture of ASDI is a verification engine that relies on several semantic web tools to check the quality of the derived data. We tested our prototype in the context of building a semantic web portal for our lab, KMi. An experimental evaluation comparing the automatically extracted data against manual annotations indicates that the verification engine enhances the quality of the extracted semantic metadata.

Design of customized web applications with OntoWeaver

OntoWeaver is our conceptual modelling methodology and a tool that support the specification and implementation of customized web applications. It relies on a number of different types of ontologies to declaratively describe all aspects of a web application. This paper focuses on the OntoWeaver customization framework, which exploits a user model, a customization rule model, and a declarative site model, to enable the design and development of customized web applications at a conceptual level. OntoWeaver makes use of the Jess inference engine to reason upon the site specifications and their underlying site ontologies according to the customization rules and the valuable user profiles to provide customization support in an intelligent way. The ontology-based approach enables the target web applications to be represented in an exchangeable format. Hence, the management and maintenance of web applications can be carried out at a conceptual level without having to worry about the implementation details. Likewise, the declarative nature of the site specifications and the generic customization framework allow the specification of customization requirements to be carried out at the conceptual level.

Reflections on five years of evaluating semantic search systems

Evaluations of semantic search systems are generally small scale and ad hoc due to the lack of appropriate resources such as test collections, agreed performance criteria and independent judgements of performance. By analysing our work in building and evaluating semantic tools over the last five years, we conclude that the growth of the semantic web led to an improvement in the available resources and the consequent robustness of performance assessments. We propose two directions for continuing evaluation work: the development of extensible evaluation benchmarks and the use of logging parameters for evaluating individual components of search systems.

An instance mapping ontology for the semantic web

Semantic data transformation plays an important role in realizing the vision of the semantic web. It supports the transformation of data in different representations into ontologies. In order to allow the task to be achieved effectively, the instructions on how to realize transformation should be well specified, preferably in a declarative and re-usable format, thus allowing the construction of robust tools which on the one hand assist users to generate and maintain mappings at design time and on the other hand perform semantic data transformation at run time. Furthermore, the transformation instructions should not only allow the generation of semantic data objects but also allow the creation of rich semantic relations between them. In this context, we developed a comprehensive instance mapping ontology. One distinctive feature of the instance mapping ontology is that it provides comprehensive support for the specification of complex mappings. Another feature is that the instance mapping ontology is representation independent, which does not limit itself to data sources in particular representations. This ontology has been applied in generating a semantic layer for the web site of the Knowledge Media Institute (KMi) at the Open University.

IIPS: an intelligent information presentation system

This paper presents the framework of an Intelligent Information Presentation System (IIPS), which provides intelligent interface presentation support for data-intensive web-based applications through the use of ontologies to drive the web site generation and maintenance process. IIPS defines a comprehensive set of ontologies to model the navigational structure, the compositional structure, and the user interfaces of data-intensive web sites, and provides a suit of tools to support site generation, maintenance, and personalization.

OntoWeaver S: supporting the design of knowledge portals

This paper presents OntoWeaver-S, an ontology-based infrastructure for building knowledge portals. In particular, OntoWeaver-S is integrated with a comprehensive web service platform, IRS-II, for the publication, discovery, and execution of web services. In this way, OntoWeaver-S supports the access and provision of remote web services for knowledge portals. Moreover, it provides a set of comprehensive site ontologies to model and represent knowledge portals, and thus is able to offer high level support for the design and development process. Finally, OntoWeaver-S provides a set of powerful tools to support knowledge portals at design time as well as at run time.