Abstract
Transformation methods from tree to lattice, in order to find quickly the spread out categories, and from lattice to tree, in order to restructure tree, are proposed. Translation from tree structure to lattice structure enables to aggregate categories which are spread out into different categories. Also, users can restructure another tree by translating from lattice to tree. Experimental comparison using data from Yahoo! Directory shows the effectiveness of the proposed methods and it is confirmed that the computation of the proposed method can be done in real time.
