Patent ID: 8024222

Claim:
A computerized method of selecting items to recommend to users, the method comprising: recording item viewing activities of each of a plurality of users of a system that provides network-based user access to a data repository of items, said item viewing activities reflecting user interests in particular items; generating, by a computer system, an item-to-item mapping structure that maps each of a plurality of the items to a respective set of similar items, wherein generating the item-to-item mapping structure comprises analyzing the recorded item viewing activities of the plurality of users to assess degrees to which particular items are similar to each other, and generating, for each of a plurality of pairs of items, a respective data value that represents the degree to which the two items of that pair are similar to each other, said data values reflecting the analysis of the recorded item viewing activities; receiving input data specifying a plurality of items selected by a user; for each of the plurality of items selected by the user, looking up, from the item-to-item mapping structure, a respective set of similar items; generating, by a computer system, a ranked set of similar items, said ranked set of similar items comprising the plurality of sets of similar items looked up from the item-to-item mapping structure; and selecting, from the ranked set of similar items, a subset of items to recommend to the user.