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Pascal Gollin, Enlarging vertex-flames in countable digraphs
Pascal Gollin, Enlarging vertex-flames in countable digraphs
A rooted digraph is a vertex-flame if for every vertex v there is a set of internally disjoint directed paths from the root to v whose set of terminal edges covers all ingoing edges of v. It was shown by Lovász that every finite rooted digraph admits a spanning subdigraph which is a vertex-flame and large, where the latter means …