Scoring missing terms in information retrieval tasks

An usual approach to address mismatching vocabulary problem is to augment the original query using dictionaries and other lexical resources and/or by looking at pseudo-relevant documents. Either way, terms are added to form a new query that will be used to score all documents in a subsequent retrieval pass, and as consequence the original query's focus may drift because of the newly added terms. We propose a new method to address the mismatching vocabulary problem, expanding original query terms only when necessary and complementing the user query for missing terms while scoring documents. It allows related semantic aspects to be included in a conservative and selective way, thus reducing the possibility of query drift. Our results using replacements for the missing query terms in modified document and passages retrieval methods show significant improvement over the original ones.