The <%= link_to "Schulze method", "http://en.wikipedia.org/wiki/Schulze_method" %> is a preferential voting system. It is based on the Condorcet method but includes a set of methods for resolving "circular" defeats.
The Schulze method is also known as Schwartz Sequential Dropping (SSD), Cloneproof Schwartz Sequential Dropping (CSSD), Beatpath Method, Beatpath Winner, Path Voting, and Path Winner.