A ranking is a partial order that, given some set of alternatives, places some before others. A preference graph, given some number of rankings, expresses the combination of all of those rankings. It is a directed, weighted graph in which the nodes represent the alternatives and the edges represent preferences. Use this to build a preference graph from individual rankings and compute a Kemeny order, aggregated preference that minimizes the number of pair-wise disagreements with the individual rankings. This is a Ruby binding built around a C language implementation of Davenport's algorithm, found on github at {wbreeze/davenport}[https://github.com/wbreeze/davenport]