Path Expression-based Smoothing of Query Likelihood Model for XML Element Retrieval

In this paper we propose a path expression-based smoothing method of query likelihood model for XML element retrieval (QLMER). Though the query likelihood model, one of the statistical language models, is regarded as an accurate term weighting scheme in document retrieval, it has not been surveyed enough in XML element retrieval. Some term Weighting schemes for XML element retrieval utilize the idea of a path expression and it is effective for accurate retrieval. Therefore, we propose the path expression-based smoothing method. We are also interested in the potential power of QLMER compared with a commonly used term weighting scheme, BM25E, which is a classic probabilistic model. Our experimental evaluations showed that the proposed smoothing method is more effective than the existing one. In addition, BM25E is more effective than QLMER even though the effectiveness improved with the proposed method.