10. A method for grafting cluster spines, further comprising the steps of: forming one or more concepts and assigning at least one of the concepts to each cluster in a set; selecting those concepts that are located in a center of one such cluster; forming a group of cluster spines based on the selected clusters that share at least one concept; identifying those cluster spines that are unique and arranging the unique cluster spines in a display; grafting at least one of the spines remaining in the group onto one of the unique spines in the display; and placing 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, wherein the steps are performed by a suitably programmed computer.
11. A method according to claim 10 , further comprising: designating the shared cluster concepts as spine concepts for that cluster spine; and generating a spine concept score vector for each cluster spine based on the spine concepts for that cluster spine.