Jan Soukup
and he will talk about the paper
J. Davies, C. Keller, L. Kleist, S. Smorodinsky, B. Walczak: A solution to Ringel's circle problem
The main question is very simple, so let me state it here to motivate you to come and hear about this beautiful result:
Consider a finite family of circles such that every point in the plane
is included in at most two circles. What is the minimum number of colors
needed to color the circles so that tangent circles are colored with
different colors? Ringel (1959) conjectured, that this number is always finite.
Same place&time as last week:
(Let me know beforehand if you plan to use zoom, otherwise I will not start it.)
See you tomorrow,
R