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As all vectors under consideration by this model are elementwise nonnegative, a cosine value of zero means that the query and document vector are [[orthogonal]] and have no match (i.e. the query term does not exist in the document being considered). See [[cosine similarity]] for further information.
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In the classic vector space model proposed by [[Gerard Salton|Salton]], Wong and Yang <ref>[http://doi.acm.org/10.1145/361219.361220 G. Salton , A. Wong , C. S. Yang, A vector space model for automatic indexing], Communications of the ACM, v.18 n.11, p.613–620, Nov. 1975</ref> the term-specific weights in the document vectors are products of local and global parameters. The model is known as [[tf-idf|term frequency-inverse document frequency]] model. The weight vector for document ''d'' is <math>\mathbf{v}_d = [w_{1,d}, w_{2,d}, \ldots, w_{N,d}]^T</math>, where
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