Provided is a method comprising: maintaining forward network structure information that, with stages arranged in a multilayer structure and each stage including one or more nodes associated with one or more words and associated in whole or in part with a point, connects nodes included in different layers with each other, in order from a higher layer toward a lower layer in a network state; acquiring one or more search word to use for a search; acquiring a node including all or part of the acquired search words and converting the acquired search words into a point; and using the forward network structure information to calculate points by sequentially adding together in a manner to inherit points, in node units of each layer, the points associated with the acquired node along all paths connected by these points from a topmost layer to the node of a predetermined layer.