1. A system for grafting cluster spines, further comprising: a concept generator to form one or more concepts and to assign at least one of the concepts to each cluster in a set; a concept selection module to select those concepts that are located in a center of one such cluster; a cluster spine module to form a group of cluster spines based on the selected clusters that share at least one concept; a spine identification module to identify those cluster spines that are unique and to arrange the unique cluster spines in a display; a cluster graft module to graft at least one of the spines remaining in the group onto one of the unique spines in the display; and a spine placement module to place those remaining cluster spines that are not grafted to one of the unique cluster spines adjacent to one of the cluster spines in the display that is most similar.