Semantic Matching in Information Retrieval

Recently, significant progress has been made in research on what we call semantic matching (SM), in web search, question answering, online advertisement, cross-language information retrieval, and other tasks. Advanced technologies based on machine learning have been developed. Let us take Web search as example of the problem that also pervades the other tasks. When comparing the textual content of query and documents, Web search still heavily relies on the term-based approach, where the relevance scores between queries and documents are calculated on the basis of the degree of matching between query terms and document terms. This simple approach works rather well in practice, partly because there are many other signals in web search (hypertext, user logs, etc.) that complement it. However, when considering the long tail of web searches, it can suffer from data sparseness, e.g., Trenton does not match New Jersey Capital. Query document mismatches occur when searcher and author use different terms (representations), and this phenomenon is prevalent due to the nature of human language.