[CR1] T.E. Cecil and P.J. Ryan, On the number of top-cycles of a tight surface in 3-space,The authors give a nice description of the results to date and of top sets and cycles. They give sharp bounds on the number of top cycles depending only on the Euler characteristic of the surface; explicit examples are given for each surface.J. London Math. Soc.30(1984) 335-341.

* 10/12/94 dpvc@geom.umn.edu -- *

*The Geometry Center*