We make use the shortest path in the is-a hierarchy to measure the conceptual similarity between the tokens in the discourse segments (Rada et al., 1989).
given tokens w and w' in the is-a hierarchy, the distance between the tokens is as follows: distance(w , w') = minimal number of is-a relationships between w and w' An is-a hierarchy in the Chinese thesaurus, as in other thesaurus such as WordNet (Miller, 1985), can be viewed as a directed acyclic graph with single root.