2019-10-29 Pascal Gollin, A Cantor-Bernstein-type theorem for spanning trees in infinite graphs

IBS Discrete Mathematics Group
Discrete Math Seminar
Pascal Gollin, A Cantor-Bernstein-type theorem for spanning trees in infinite graphs
October 29 2019, Tuesday @ 4:30 PM ~ 5:30 PM
Room B232, IBS (기초과학연구원)
Speaker
Pascal Gollin
IBS Discrete Mathematics Group
dimag.ibs.re.k...
Given a cardinal $\lambda$, a $\lambda$-packing of a graph $G$ is a family of $\lambda$ many edge-disjoint spanning trees of $G$, and a $\lambda$-covering of $G$ is a family of spanning trees covering $E(G)$.
We show that if a graph admits a $\lambda$-packing and a $\lambda$-covering then the graph also admits a decomposition into $\lambda$ many spanning trees. In this talk, we concentrate on the case of $\lambda$ being an infinite cardinal. Moreover, we will provide a new and simple proof for a theorem of Laviolette characterising the existence of a $\lambda$-packing, as well as for a theorem of Erdős and Hajnal characterising the existence of a $\lambda$-covering.
Joint work with Joshua Erde, Attila Joó, Paul Knappe and Max Pitz.