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Bermond-Thomassen Conjecture


The Bermond-Thomassen conjecture asserts that a finite loopless directed graph with no repeated arcs and minimum outdegree at least 2k-1 contains k vertex-disjoint directed cycles, for every positive integer k. Oppositely directed arcs are allowed, so directed cycles of length 2 are included.

Bang-Jensen et al. (2026) proved an asymptotic version. For an absolute constant C>0 and all sufficiently large k, minimum outdegree at least 2k+Ck^(3/4)sqrt(lnk) suffices. This does not settle the conjectured threshold 2k-1. Bang-Jensen et al. (2026) report AI assistance in refining error estimates and the martingale construction.


See also

Directed Graph, Graph Cycle

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References

Bang-Jensen, J.; Wang, G.; and Wang, Y. "An Asymptotic Bound for the Bermond-Thomassen Conjecture." 8 Oct 2026. https://arxiv.org/abs/2610.11517.

Cite this as:

Weisstein, Eric W. "Bermond-Thomassen Conjecture." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/Bermond-ThomassenConjecture.html

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