While assessing the quality of clustering is a notably hard problem, given a gold standard G we can calculate the Rand index (RI) of a clustering C, a common quality measure in the literature, determined as follows (Rand, 1971;Manning et al., 2008): where W is the union set of all the words in C and δ(w, w ) = 1 if any two words w and w are in the same cluster both in C and in the gold standard G or they are in two different clusters in both C and G, otherwise δ(w, w ) = 0.
we calculate the percentage of word pairs that are in the same configuration in both C and G. For the gold standard G we use the clustering induced by the sense annotations provided in our datasets for each snippet (i.e., each cluster contains the snippets manually associated with a particular Wikipedia subtopic  Results.