An Algebra for Slope-Monotone Closed Curves. - Kokichi Sugihara; Toshiyuki Imai; Takeshi Hataguchi (Int. J. Shape Model., 1997)

An invertible Minkowski sum of figures. - Kokichi Sugihara; Toshiyuki Imai; Takeshi Hataguchi (Syst. Comput. Jpn., 1998)