subtype(rectangle,square).
attribute(rectangle,corner_x,int).
attribute(rectangle,corner_y,int).
attribute(rectangle,length,int).
attribute(rectangle,width,int).
attribute(shape, color, int).
subtype(shape,circle).
subtype(shape,rectangle).
attribute(circle,center_x,int).
attribute(circle,center_y,int).
attribute(circle,radius,long).