Abstract: Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for storing, in an index associated with a document, a particular term that occurs in the document, wherein the particular term comprises n words, and wherein n is greater than 1; identifying a substitute term of the particular term; and in response to identifying the substitute term of the particular term, storing, in the index associated with the document, (i) the substitute term of the particular term, and (ii) data indicating that the substitute term spans the n words of the particular term.

Abstract: Methods, systems, and apparatus, including computer programs encoded on computer storage media, for index-side synonym expansion. One method includes obtaining a token sequence for a resource and indexing a particular token in the token sequence. The indexing includes obtaining a diacritically canonicalized form of the particular token; determining that the diacritically canonicalized form of the particular token is different from the particular token; and storing data associating the resource with both the particular token and the different diacritically canonicalized form of the particular token as index terms for the resource in a search engine.

Abstract: Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for storing, in an index associated with a document, a particular term that occurs in the document, wherein the particular term comprises n words, and wherein n is greater than 1; identifying a substitute term of the particular term; and in response to identifying the substitute term of the particular term, storing, in the index associated with the document, (i) the substitute term of the particular term, and (ii) data indicating that the substitute term spans the n words of the particular term.