8. The computer system of claim 7 , wherein filtering comprises pruning weakly linked potential variation-phrase pairs from the variation-phrase set, wherein said pruning comprises: for each discrete subset of potential variation-phrase pairs in the variation-phrase set: determining whether the current discrete subset of potential variation—phrase pairs satisfies a predetermined pruning criteria; and if the current discrete subset of potential variation-phrase pairs fails to satisfy the predetermined pruning criteria, pruning weakly linked potential variation-phrase pairs from the discrete subset of potential variation-phrase pairs.
8. The computer system of claim 7 , wherein filtering comprises pruning weakly linked potential variation-phrase pairs from the variation-phrase set, wherein said pruning comprises: for each discrete subset of potential variation-phrase pairs in the variation-phrase set: determining whether the current discrete subset of potential variation—phrase pairs satisfies a predetermined pruning criteria; and if the current discrete subset of potential variation-phrase pairs fails to satisfy the predetermined pruning criteria, pruning weakly linked potential variation-phrase pairs from the discrete subset of potential variation-phrase pairs. 10. The computer system of claim 8 , wherein pruning weakly linked potential variation-phrase pairs from the variation-phrase set is performed recursively on each discrete subsets of potential variation-phrase pairs in the variation-phrase set.