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Borodin-Kostochka Conjecture


The Borodin-Kostochka conjecture asserts that a finite simple graph G with maximum vertex degree Delta(G)>=9 satisfies

 chi(G)<=max{omega(G),Delta(G)-1},

where chi(G) is the chromatic number and omega(G) is the clique number (Borodin and Kostochka 1977).

Reed (1999) proved the inequality for sufficiently large maximum vertex degree. Chen (2026) obtained the explicit threshold Delta(G)>=750 using a randomized partial vertex coloring and finite certified estimates. The conjecture remains open at the threshold 9.


See also

Brooks' Theorem, Chromatic Number, Clique Number, Maximum Vertex Degree

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References

Borodin, O. V. and Kostochka, A. V. "On an Upper Bound of a Graph's Chromatic Number, Depending on the Graph's Degree and Density." J. Combin. Th. Ser. B 23, 247-250, 1977. https://doi.org/10.1016/0095-8956(77)90037-5.Chen, L. "The Borodin-Kostochka Inequality from Degree 750." 6 Nov 2026. https://arxiv.org/abs/2611.05423v2.Reed, B. "A Strengthening of Brooks' Theorem." J. Combin. Th. Ser. B 76, 136-149, 1999. https://doi.org/10.1006/jctb.1998.1891.

Cite this as:

Weisstein, Eric W. "Borodin-Kostochka Conjecture." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/Borodin-KostochkaConjecture.html

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