Patent ID: 8756216

Claim:
A computer-implemented method for searching a collection of content, comprising: under control of one or more computer systems configured with executable instructions, selecting a first subset of a set of content descriptors for the collection of content; building an index tree for the first subset of content descriptors; refining the index tree at least in part by, for each content descriptor outside the first subset: indexing the content descriptor at least in part by determining a lowest level node of the index tree having an index descriptor nearest in distance to the content descriptor with respect to a metric and adding the content descriptor to the lowest level node, the index descriptor including data summarizing one or more characteristics of the lowest level node, the index descriptor further comprising information about at least one of a mean or a center for a plurality of content descriptors associated with the lowest level node; modifying the index descriptor of the lowest level node at least to be nearer in distance to the content descriptor with respect to the metric; and updating an index descriptor of each node on a path between the lowest level node and a root node of the index tree, the updating being based at least in part upon a learning rate; and making the refined index tree available to facilitate searching the collection of content.