cos 類似度

cosine similarity。Orchini 類似度 (Orchini similarity)。Tucker 合同係數 (Tucker coefficient)

$ \cos \theta=\frac{a\cdot b}{|a||b|}

$ -1\le\cos\theta\le 1

1 に近い程類似してゐる

MinHash (min-wise independent permutations locality sensitive hashing scheme)

大塚-落合類似度 (Otsuka-Ochiai similarity)