Web Semantics for Personalized Information Retrieval

Query Expansion Techniques

The most challenging issue to consider in web information retrieval is to resolve the ambiguity arising out of poorly defined queries. Information requirements may vary with the different search sessions. Query expansion techniques aims at reformulating the query to meet the user requirements. Mainly two types of techniques are available- global and local. Global methods utilizes the existing thesaurus /WorldNet, create thesaurus automatically or perform spell check. Local methods consist of recording the relevance, pseudo relevance and indirect relevance feedback. Relevance feedback is recorded either implicitly or explicitly. Implicit user feedback is calculated by observing their behavior on web. These methods are further divided into word co-occurrence, probabilistic methods, context and location based methods. Figure 2 represents schematically the classification of query expansion techniques.

Figure 2.

Various Types of Query Expansion Techniques

Various methods for creating user profiles are given in next sub-section.