It is computed as twice the ratio between the size of the intersection of the two feature sets and the sum of the sizes of the individual feature sets: where F(w) = {c : P(c|w) > 0} 29According to this measure, the similarity between words with no shared features is zero and the similarity between words with identical feature sets is 1.
as shown below, this formula is equivalent to a special case in the CR framework: the harmonic mean of precision and recall (or F-score) using the additive type-based CRM.