2. The method of claim 1 , wherein the relationship is a social relationship.
2. The method of claim 1 , wherein the relationship is a social relationship. 4. The method of claim 2 , wherein the relationship is selected from a group consisting of a relationship based on group membership specified by a user represented by the respective node, a relationship based on similarity between content generated by the users represented by the respective node and the neighboring nodes, and a relationship based on similarity of a web-site visiting pattern.