19. A method comprising: obtaining a set of one or more taxonomies wherein each of the taxonomies includes one root node and one or more hierarchically ordered paths, wherein each hierarchically ordered path includes the root node and a hierarchically ordered sequence of concept nodes; receiving a first set of first set concepts and a second set of second set concepts; determining a plurality of concept pairs, wherein each concept pair includes one of the first set concepts and one of the second set concepts; determining, for each one of the concept pairs, an associated length of a nondiverging intersection of a first sub-path of one of the hierarchically ordered paths from the root node of one of the taxonomies to a first concept node representing the first set concept and a second sub-path of one of the hierarchically ordered paths from the root node of the one of the taxonomies to a second concept node representing the second set concept, and an associated length of a first portion of the first sub-path from a last concept node included in the nondiverging intersection to the first concept node, and an associated length of a second portion of the second sub-path from the last concept node included in the nondiverging intersection to the second concept node; determining pairwise similarity values associated with each of the concept pairs based on ratios based on associated lengths of nondiverging intersections determined by the determining the associated length of the nondiverging intersection and the associated lengths of the first and second portions, wherein a pairwise similarity value indicating a high similarity is determined for association with concept pairs associated with nonempty nondiverging intersections including the root node and hierarchically immediate successor nodes of the root node that are included in the first sub-path and the second sub-path; and determining a concept set similarity value based on a weighted sum of the pairwise similarity values associated with optimal selected ones of the concept pairs.
19. A method comprising: obtaining a set of one or more taxonomies wherein each of the taxonomies includes one root node and one or more hierarchically ordered paths, wherein each hierarchically ordered path includes the root node and a hierarchically ordered sequence of concept nodes; receiving a first set of first set concepts and a second set of second set concepts; determining a plurality of concept pairs, wherein each concept pair includes one of the first set concepts and one of the second set concepts; determining, for each one of the concept pairs, an associated length of a nondiverging intersection of a first sub-path of one of the hierarchically ordered paths from the root node of one of the taxonomies to a first concept node representing the first set concept and a second sub-path of one of the hierarchically ordered paths from the root node of the one of the taxonomies to a second concept node representing the second set concept, and an associated length of a first portion of the first sub-path from a last concept node included in the nondiverging intersection to the first concept node, and an associated length of a second portion of the second sub-path from the last concept node included in the nondiverging intersection to the second concept node; determining pairwise similarity values associated with each of the concept pairs based on ratios based on associated lengths of nondiverging intersections determined by the determining the associated length of the nondiverging intersection and the associated lengths of the first and second portions, wherein a pairwise similarity value indicating a high similarity is determined for association with concept pairs associated with nonempty nondiverging intersections including the root node and hierarchically immediate successor nodes of the root node that are included in the first sub-path and the second sub-path; and determining a concept set similarity value based on a weighted sum of the pairwise similarity values associated with optimal selected ones of the concept pairs. 20. The method of claim 19 wherein: obtaining the set of one or more taxonomies comprises obtaining the set of one or more taxonomies wherein each of the taxonomies includes one root node and one or more hierarchically ordered paths, wherein each hierarchically ordered path includes the root node and a hierarchically ordered sequence of concept nodes, wherein each of the concept nodes represents a concept, wherein each hierarchically ordered path is indicated by an associated ordered vector of branch indicators, wherein each branch indicator indicates an edge between an immediate predecessor concept node and an immediate successor node based on the hierarchically ordered sequence, and determining, for each one of the concept pairs, an associated length of a nondiverging intersection of a first sub-path comprises determining, for each one of the concept pairs, a nondiverging intersection of one of the vectors associated with the first sub-path of the one of the hierarchically ordered paths from the root node to the first concept node and one of the vectors associated with the second sub-path of the one of the hierarchically ordered paths from the root node to the second concept node.