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Similarity learning is an area of supervised machine learning in artificial intelligence. It is closely related to regression and classification, but the goal is to learn from examples a similarity function that measures how similar or related two objects are. It has applications in ranking, in recommendation systems and face verification. == Learning setup == There are three common setups for similarity and metric distance learning. * ''Regression similarity learning''. In this setup, pairs of objects are given together with a measure of their similarity . The goal is to learn a function that approximates for every new labeled triplet example . This is typically achieved by minimizing a regularized loss . * ''Classification similarity learning''. Given are pairs of similar objects and non similar objects . An equivalent formulation is that every pair is given together with a binary label that determines if the two objects are similar or not. The goal is again to learn a classifier that can decide if a new pair of objects is similar or not. * ''Ranking similarity learning''. Given are triplets of objects whose relative similarity obey a predefined order: is known to be more similar to than to . The goal is to learn a function such that for any new triplet of objects , it obeys . This setup assumes a weaker form of supervision than in regression, because instead of providing an exact measure of similarity, one only has to provide the relative order of similarity. For this reason, ranking-based similarity learning is easier to apply in real large scale applications. A common approach for learning similarity, is to model the similarity function as a bilinear form. For example, in the case of ranking similarity learning, one aims to learn a matrix W that parametrizes the similarity function . 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「Similarity learning」の詳細全文を読む スポンサード リンク
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