INDEX-SIDE SYNONYM GENERATION

Methods, systems, and apparatus, including computer programs encoded on computer storage media, for index-side synonym expansion are disclosed. Some implementations include actions of obtaining a token sequence for a resource, wherein each token in the token sequence comprises one or more characters. The actions also include selecting a token from the token sequence, wherein the selected token comprises at least one numeric portion having one or more contiguous numeric characters, and at least one non-numeric portion having one or more non-numeric characters. Further actions include generating a new token corresponding to each of the at least one numeric portions of the selected token and storing data associating the selected token and each of the new tokens corresponding to the at least one numeric portion of the selected token as index terms for the resource, wherein the search engine index is accessed to augment search queries.