16. The non-transitory machine-readable medium of claim 15 , wherein rewriting the at least one optional search operator in the first initial search query using the at least one required search operator and the at least one exclusion search operator comprises using one of the at least one exclusion search operator at a beginning of the first rewritten search query.
15. A non-transitory machine-readable medium embodying a set of instructions that, when executed by a processor, cause the processor to perform operations, the operations comprising: receiving a first initial search query from a first user, the first initial search query comprising at least one search operator and at least one search term; generating a first rewritten search query based on the first initial search query, the generating the first rewritten search query comprising rewriting at least one optional search operator in the first initial search query using at least one required search operator and at least one exclusion search operator in response to a determination that the first initial search query comprises the at least one optional search operator and does not comprise any required search operators; generating a first set of search results for the first rewritten search query; and causing the first set of search results to be presented to the first user.