A Condorcet social choice procedure elects the candidate that beats every other candidate under simple majority when such a candidate exists. The reinforcement axiom roughly states that given two groups of individuals, if these two groups select the same alternative, then this alternative must...

According to a given quota q, a candidate a is beaten by another candidate b if at least a proportion of q individuals prefer b to a. The q-Condorcet efficiency of a voting rule is the probability that the rule selects a q-Condorcet winner (q-CW), that is any candidate who is never beaten under...