On 16.12.2010 at 12:20 in S11, there is the following noon lecture:
This is joint work with Jan Kyncl, Marcus Schaefer, Daniel Stefankovic.
In a surface, draw a pair of curves with a large number of intersections. Must the drawing contain any particular sub--structures? A spiral is especially desirable because it can be used to simplify drawings in a number of contexts (string graphs, quadratic word equations).
However, we show that for every n there is a pair of curves in the plane with n intersections, but that do not form a spiral. This proof utilizes train tracks, a topological tool that provides a compressed representation for densely packed curves.
Webmaster: kamweb.mff.cuni.cz Modified: 19. 10. 2010