Many tasks in music information retrieval, such as recommendation, and
playlist generation for online radio, fall naturally into the query-by-example
setting, wherein a user queries the system by providing a song, and the system
responds with a list of relevant or similar song recommendations. Such
applications ultimately depend on the notion of similarity between items to
produce high-quality results. Current state-of-the-art systems employ
collaborative filter methods to represent musical items, effectively comparing
items in terms of their constituent users.