Schwartz Set

In voting systems, the Schwartz set is the union of all Schwartz set components. A Schwartz set component is any non-empty set S of candidates such that

1. Every candidate inside the set S is pairwise unbeaten by every candidate outside S; and
2. No non-empty proper subset of S fulfills the first property.

A set of candidates that meets the first requirement is also known as an undominated set.

The Schwartz set provides one standard of optimal choice for an election outcome. Voting systems that always elect a candidate from the Schwartz set pass the Schwartz criterion. The Schwartz set is named for political scientist Thomas Schwartz.