Of course it does. It's similarly unreasonable to call a Möbius Strip with a disc attached along the boundary circle a "plane"[1], the surface of Cartesian (x,

Of course it does. It's similarly unreasonable to call a Möbius Strip with a disc attached along the boundary circle a "plane"[1], the surface of Cartesian (x, y) coordinates a "line"[2], and numbers having counterintuitive special features, "normal". [1] http://en.wikipedia.org/wiki/Real_projective_plane http://en.wikipedia.org/wiki/Real_projective_plane [2] http://en.wikipedia.org/wiki/Complex_line http://en.wikipedia.org/wiki/Complex_line