Decomposition of oriented k-partition-connected digraphs
Let D=(V,A) be a digraph whose underlying graph is k-partition-connected, and let r0∈V be a node of in-degree 0. Suppose that the in-degree of every other node is at least k. Is it true that D can be decomposed into k weakly connected spanning subgraphs, so that every node v∈V−r0 has positive in-degree in each subgraph?
Remarks
Let M1 be the cycle matroid of the underlying undirected graph of D, and let M2 be the partition matroid where each class consists of the set of edges entering a given node v∈V−r0. The problem can be formulated as follows:
Is it true that if both M1 and M2 contain k disjoint spanning sets, then there are k disjoint common spanning sets?
This statement is known to be true for strongly base orderable matroids [1]; however, the cycle matroid of a graph is not necessarily base orderable.