Pairwise methods are voting systems/electoral systems in which
voters can submit ranked ballots which are used to simulate
head-to-head elections between every candidate. The winner of
said elections is the candidate who wins all pairwise matchups.
These methods differ in the tie-breakers they employ. Condorcet,
Copeland, and many others have devised methods of dealing with this
problem, also known as Condorcet's paradox.