Items related by a tree are further organized by determining a depth-first search of the tree having an optimum value associated therewith. The associated value of a depth-first search is based upon an order of considering items in the tree, and similarity values between pairs of items in the tree....http://www.google.com.tw/patents/US6563521?utm_source=gb-gplus-share專利 US6563521 - Method, article and apparatus for organizing information
