1. One or more computer-readable media having computer-executable instructions embodied thereon that, when executed, perform a method for, in response to a query, presenting search results to a user having regions emphasized therein in accordance with a highlighting scheme, the method comprising: receiving a query having one or more search terms therein; determining a low-level grammatical function served by the one or more search terms within the query by analyzing a semantic relationship between the one or more search terms; identifying at least one role that corresponds to the determined function, wherein the at least one role represents a high-level purpose of the one or more search terms that is derived from the low-level grammatical function; distilling a proposition from the one or more search terms, wherein the proposition represents a logical meaning of content within the query comparing the at least one identified role and the proposition against semantic representations retained in a semantic index to determine a matching set, wherein the semantic representations comprise a linguistic representation derived from content of passages within at least one document, wherein determining the matching set comprises: (a) identifying a group of the semantic representations that correspond with the at least one identified role; and (b) selecting from the group the semantic representations that correspond with the proposition; identifying the passages that are mapped to the matching set of semantic representations; applying emphasis to the regions of the identified passages according to a highlighting scheme; and presenting the emphasized regions of the identified passages to the user as the search results relevant to the query.