1. A method, implemented by one or more computing devices, for performing a search, comprising: receiving a query, and associated query information; identifying context information associated with the query, pertaining to a context in which the query has been submitted, the context having a plurality of parts; transforming the context information into a plurality of context concept vectors in a semantic space, using a deep learning model, each context concept vector representing one of the plurality of parts of the context; receiving document information associated with a document, the document having a plurality of parts; transforming the document information into a plurality of document concept vectors in the same semantic space, using the deep learning model, each document concept vector representing one of the plurality of parts of the document; performing pairwise comparisons of the context concept vectors with the document concept vectors to produce a relevance measure, indicating a degree of a defined semantic relationship between the context and the document; determining a ranking score for the document based at least on the relevance measure; and providing a search result based on the ranking score.