Enlarging vertex-flames in countable digraphs
Combinatorics
2021-06-17 v2
Abstract
A rooted digraph is a vertex-flame if for every vertex there is a set of internally disjoint directed paths from the root to whose set of terminal edges covers all ingoing edges of . It was shown by Lov\'{a}sz that every finite rooted digraph admits a spanning subdigraph which is a vertex-flame and large, where the latter means that it preserves the local connectivity to each vertex from the root. A structural generalisation of vertex-flames and largeness to infinite digraphs was given by the third author and the analogue of Lov\'{a}sz' result for countable digraphs was shown. We strengthen this result by proving that in every countable rooted digraph each vertex-flame can be extended to a large vertex-flame.
Keywords
Cite
@article{arxiv.2003.06178,
title = {Enlarging vertex-flames in countable digraphs},
author = {Joshua Erde and J. Pascal Gollin and Attila Joó},
journal= {arXiv preprint arXiv:2003.06178},
year = {2021}
}