The Jaccard measure is the cardinality ratio of the intersection and union of attribute sets (atts(w n ) is the attribute set for w n ): The generalised Jaccard measure allows each relation to have a significance weight (based on word, attribute and relation frequencies) associated with it: Grefenstette originally used the weighting function: where f (w i , a j ) is the frequency of the relation and n(a j ) is the number of different words a j appears in relations with.
context Description W(L 1 R 1 ) one word to left or right W(L 1 ) one word to the left W(L 1,2 ) one or two words to the left W(L 1−3 ) one to three words to the left Table 1: Window extractors we have found that using the t-test between the joint and independent distributions of a word and its attribute: gives superior performance (curran and Moens, 2002) and is therefore used for our experiments.