Thus our first-order character kernel c 1 is: We use c 1 and equation 1 to construct a firstorder plot kernel (which we call k 1 ), and also as an ingredient in a second-order character kernel c 2 which takes into account the curve of pairwise frequencies u, u between two characters u and u in the same novel.
u is similar to v if, for some relationships of u with other characters u , there are similar characters v who serves the same role for v. We use c 2 and equation 1 to construct our full plot kernel k 2 .