Bang-Jensen–DeVos–Mütze conjecture on strong tournaments in semicomplete digraphs
Let be a semicomplete digraph, meaning that for every pair of distinct vertices, at least one of the two possible directed arcs is present. A digraph is -strong if it has at least vertices and remains strongly connected after the deletion of any subset of vertices. A tournament is an oriented complete graph, and a spanning subdigraph contains all vertices of .
Bang-Jensen–DeVos–Mütze conjecture. Every -strong semicomplete digraph on at least vertices contains a spanning -strong tournament.
The source presents this as a conjecture supported by its arc-connectivity analogue, while also giving sharpness results for the order and connectivity bounds and a counterexample for a broader class of almost semicomplete digraphs. Its status is not resolved in the supplied text.
References
Primary source
Tong Zhou, Jørgen Bang-Jensen, Jia Zhou and Jin Yan, “K-Arc-Strong Orientations Of Semicomplete Digraphs”, arXiv:2607.17116 (2026).
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