19. The system of claim 17 , wherein the control circuitry determines that the portion of the third syntactic mapping of the merged query corresponding to second query terms and the second syntactic mapping of the second query are syntactically equivalent by determining that any syntactic identifier present in the portion of the third syntactic mapping is also present in the second syntactic mapping.
17. The system of claim 11 , wherein the control circuitry determines a syntactic mapping of any query by at least grammatically parsing the query and assigning syntactic identifiers to parsed elements of the query.