Dartmouth Dartmouth Mathematics Colloquium MATH

Thursday, April 17, 1997

4:00-5:00 pm

102 Bradley Hall

Professor Dan Archdeacon

University of Vermont

speaks on

Sewing Ribbons on Graphs in Space

Abstract. A ribbon is a rectangle with one side distinguished as the seam. Suppose that you want to sew the seam of a ribbon onto a graph embedded in 3-space. Even harder, suppose that you want to simultaneously sew several ribbons on the same graph. If the seams intersect in a complicated way, it can be impossible to sew the ribbons in the desired manner.

In this talk we examine when these sewn ribbon complexes embed in
3-space. We give several characterizations of these spatial ribbons
complexes. We also consider the theoretical and algorithmic
implications of our characterizations. The problem seems to lie right
on the boundary (assuming there is one) between polynomial and
NP-complete problems.

High tea will be served at 3:30 pm in the Lounge.
Emmy's. Certain refreshments will be available at Emmy's after the talk.
Host. Michael Orrison is the host. Anybody who is interested in having dinner with the speaker should contact Michael at 643-2374.