The Copeland measure of Condorcet choice functions (Q1343145)

Consider the class of all (round-robin) tournaments \(T\). A choice function \(F(T)\) is a mapping that assigns a non-empty subset of the set of the vertices of \(T\) to each tournament \(T\); the members of \(F(T)\) are deemed to be the winners, or most dominant participants, of the tournament. The Copeland choice function \(C(T)\) consists of those vertices of \(T\) that have the largest score. The authors propose a measure for comparing an arbitrary choice function with the Copeland choice function; and they compute this measure for various familiar choice functions.