Finally, the curve returns to a convex circle, as required for the top sets of a tight immersion . Note that the polyhedral circle stars large, gets smaller toward the critical level, then grows larger again for this final step; this is in keeping with the fact that this projective plane forms the central M- region of the tight immersion and should have "negative curvature" everywhere; that is, it should have the basic shape of a hyperboloid of one sheet: wide at the top and bottom and thin in the middle.
9/29/94 dpvc@geom.umn.edu --
The Geometry Center