Hello all, Here is the handout for the talk. Honza
On 4/13/2022 2:23 PM, Robert Samal wrote:
Hi all,
just a reminder: tomorrow we will have the next edition of "doktorandsky seminar". As announced on http://kam.mff.cuni.cz/dokt_seminar/, our speaker will be 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 (https://gilkalai.wordpress.com/2021/12/11/to-cheer-you-up-in-difficult-times..., https://arxiv.org/abs/2112.05042)
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:
Time: Thursday 9:50-12:10 Place: S6 For people who cannot come, zoom: https://cesnet.zoom.us/j/95284272991?pwd=aGxTM29NZVZGUjJWcG8vYWRmYXRSQT09 *(Let me know beforehand if you plan to use zoom, otherwise I will not start it.) *
See you tomorrow,
R
Robert Šámal IÚUK MFF UK -- CSI of Charles University
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