[Settfa] Tuesday 25/09, Stefan Geschke

[kubis at math.cas.cz]

 ------------------------------------------------------------------------- 

 Tuesday 25th September, 10:00am 
 ------------------------------------------------------------------------- 

 Speaker:Stefan Geschke, University of Hamburg, Germany
 Title: Obstructions to the existence of normal spanning trees in uncountable graphs

 Abstract  
I am going to talk about joint work with Nathan Bowler and Max Pitz.
A normal spanning tree of a graph is a subgraph that is a rooted tree such that the two ends of any edge in the original graph are comparable in the tree.  In other words, all the original edges are along branches of the tree.  Every countable connected graph has a normal spanning tree.  I discuss the landscape of uncountable trees without normal spanning trees answering questions by Diestel and Leader. 

 For more information see the seminar web page at 
 https://calendar.math.cas.cz/set-theory-and-analysis-actual .