The author adopted the third research type from Table 3.1 as follows.
1. In the Research Clarification stage, the author undertook an intensive literature review, discussions with supervisors and the research communities in seminars and
3. METHODOLOGY
through multiple platforms like LinkedIn25, Research Gate26. This stage has been
the foundation to define the research goal and overall research plan (Chapter 1). 2. In the Descriptive Study I stage, the literature on semantic search and related
Semantic Web technologies was reviewed to achieve an increased understanding of the problem domain (Chapter 2).
3. In the Prescriptive Study stage, the author used the understanding attained from literature review (from the previous stages) to evaluate the tools available in the semantic community to support semantic search (Chapter 4). The evaluation of related tools helped the author to identify the criteria to be met by semantic search tools. The criteria was formulated into a proposed framework (Chapter 5). Indi- vidual modules of the framework will be detailed in Chapter 6, 7, 8 and 9. 4. In the Descriptive Study II stage, an initial evaluation of the developed framework
was carried out by developing a prototype based on the proposed model (Chapter
10). The researcher used British Library free datasets and SPARQL end-point as a test-bed for initial evaluation. The method was then applied to some other datasets such as DBPedia.
Figure 3.4 maps the thesis chapters against the DRM model. Chapter 1 covers the clarification stage and identifies the research goals from literature review. At this stage, the author short-lists the research questions to be explored at later stages. The Descriptive Study I stage (covered in Chapters2and3), explores the background of the semantic data technologies and pinpoints the challenges faced by semantic search. The author focuses more on the Prescriptive Study stage (covered in Chapters 4, 5,6,7, 8and 9) to find out the limitations of existing semantic search systems and consequently proposes a framework as a solution to facilitate semantic search. Finally, the Descriptive Study II stage (covered in Chapter 10) describes the initial evaluation of the developed framework followed by Chapter 11 to sum up the conclusions.
25http://linkedin.com - LinkedIn is a business-oriented social networking service.
26http://www.researchgate.net - ResearchGate is a social networking site for scientists and researchers to share their research ideas.
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Figure 3.4: Comprehensive thesis structure in context of the adopted methodology (Source: Author, 2015)
3.6
Summary
This chapter has explained the methodology adopted for this research work. [Blessing and Chakrabarti,2009] define seven different design research approaches that can be adopted based on project type. The author has chosen the third type of methodology that involves four stages i.e. (i) Research Clarification, (ii) Descriptive Study I, (iii) Prescriptive Study, and (iv) Descriptive Study II.
At the first stage of the methodology, the author identified the research goals from lit- erature review and peer discussions. Descriptive Study I stage identified the shortcomings of existing semantic search tools which was followed by the Prescriptive Study stage in terms of the proposed framework and its prototype embodiment. Finally, the Descriptive Study II stage involved initial evaluation of the developed framework.
The next chapter utilises the literature review from Descriptive Study I stage in Chap- ter 2 and undertakes Prescriptive Study to analyse existing semantic search tools.
Chapter 4
Existing Semantic Search Systems
4.1
Introduction
Semantic search promises to provide more relevant and accurate results as compared to the syntax based search. However, in order to utilise semantic search, end users need to master the complexity of its query languages and familiarity with the underlying ontolgies [Zhou et al.,2007]. The semantic search approaches are characterised by their high level of diversity both in their features as well as their capabilities [Elbedweihy et al., 2012a]. [Uren et al.,2007] categorised informal semantic search systems in four categories i.e. (i) keywords-based, (ii) form-based, (iii) view-based and (iv) natural language based systems. Later [Wei et al., 2008] classified semantic search systems into six categories based on their methodologies and scope. They did not limit their investigation to certain criteria instead they undertook a generic approach and presented a framework for semantic search comprising of six components i.e. semantic data acquisition, knowledge acquisition, data integration and consolidation, semantic search mechanisms, semantic search services, and result presentation. Their framework lacks details of the components and it does not say anything about the query interface. Similarly, the search interface evaluation conducted by [Elbedweihy et al., 2012a] showed that the Natural Language Interfaces (NLIs) are the most acceptable by end-users (who prefer NLIs over keyword matching, menu-based or graphical interfaces). Investigations by [Danica and Bontcheva, 2009] and [Kaufmann and Bernstein,2010] on usefulness and usability of NLIs have shown that end users need a similar means of query access (as provided by conventional search interfaces) and NLIs are believed to be a practical solution.
This chapter looks into existing systems that support controlled or full Natural Lan- guage (NL) queries to access linked open datasets. It is not the author’s intention to cover
4. EXISTING SEMANTIC SEARCH SYSTEMS
all existing approaches, but to review the state-of-the-art to investigate the capabilities of different systems with respect to their approach, scope, capacity of query translation, natural language support etc. Section 4.2 provides an overview of the natural language based semantic search systems. Section4.3provides an analysis of the available NL based systems and identifies the NLIs with maximum features. Section 4.4 further compares the short listed NLIs from Section4.3. The chapter finishes with discussion (Section 4.5) and summary (Section 4.6).