Introduction to Information Retrieval

Introduction to Information Retrieval
From angles to cosines
• The following two notions are equivalent.
• Rank documents according to the angle between query and
document in decreasing order
• Rank documents according to cosine(query,document) in
increasing order
• Cosine is a monotonically decreasing function of the angle
for the interval [0 ◦ , 180 ◦ ]
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