Smith set
In voting systems, the Smith set, named after John H. Smith, but also known as the top cycle, or as Generalized Top-Choice Assumption (GETCHA), is the smallest non-empty set of candidates in an election such that more voters prefer any candidate in the set over any candidate not in the set in head-to-head matchups. The Smith set is one way to determine who the best candidates in an election are.  Voting systems that always elect a candidate from the Smith set pass the Smith criterion and are said to be "Smith-efficient".