Density condensation of Boolean formulas. - Youichi Hanatani; Takashi Horiyama; Kazuo Iwama (Discret. Appl. Math., 2006)

New Graph Calculi for Planar Non-3-Colorable Graphs. - Youichi Hanatani; Takashi Horiyama; Kazuo Iwama; Suguru Tamaki (IEICE Trans. Fundam. Electron. Commun. Comput. Sci., 2008)