Imagine there is an election between four candidates: A, B, C and D. The first matrix below records the preferences expressed on a single ballot paper, in which the voter's preferences are (B, C, A, D); that is, the voter ranked B first, C second, A third, and D fourth. In the matrix a '1' indicates that the runner is preferred on this voter's ballot over the 'opponent', while a '0' indicates that the runner is defeated. For example, in the following matrix, A beats D: