11. A computer-implemented method for grafting cluster spines, comprising: obtaining cluster spines, each cluster spine comprising two or more clusters of documents; generating a score vector for each of the cluster spines based on the documents within the clusters for that spine; comparing the score vectors of the cluster spines; placing in a display those cluster spines that are sufficiently dissimilar from the other cluster spines based on the comparison; and grafting at least one remaining cluster spine onto one of the displayed spines such that no overlap of the placed spine and the remaining spine occurs.
11. A computer-implemented method for grafting cluster spines, comprising: obtaining cluster spines, each cluster spine comprising two or more clusters of documents; generating a score vector for each of the cluster spines based on the documents within the clusters for that spine; comparing the score vectors of the cluster spines; placing in a display those cluster spines that are sufficiently dissimilar from the other cluster spines based on the comparison; and grafting at least one remaining cluster spine onto one of the displayed spines such that no overlap of the placed spine and the remaining spine occurs. 12. A method according to claim 11 , further comprising: identifying an anchor point on the displayed spine; and placing the remaining cluster spine on the displayed spine at the anchor point.