TOPICS
Search

Alon-Krivelevich Conjecture


The Alon-Krivelevich conjecture asserts that there is an absolute constant C such that every finite simple graph that is bipartite of maximum vertex degree Delta>=2 has choice number at most ClnDelta (Alon and Krivelevich 1998).

Yu and Yu (2026) disprove the conjecture by constructing bipartite graphs with

 ch(G)>=(1/(32)-o(1))((lnDelta)^2)/((lnlnDelta)^3)

as Delta->infty along their family. For integers k>=2 and r>=0, the two parts are disjoint copies of all k-element subsets of a (2k-1)-element set. Two vertices are adjacent when their corresponding subsets intersect in at most r elements. With each list coloring list equal to its corresponding subset, no proper list coloring exists whenever r^2>2(2k-1)ln(2k-1). Yu and Yu (2026) credit an OpenAI model with finding the construction and proof and report independently checking the mathematical content.


See also

Bipartite Graph, Choice Number, List Coloring

Explore with Wolfram|Alpha

References

Alon, N. and Krivelevich, M. "The Choice Number of Random Bipartite Graphs." Ann. Combin. 2, 291-297, 1998. https://doi.org/10.1007/BF01608526.Yu, J. and Yu, G. "A Counterexample to the Alon-Krivelevich Conjecture and a New Lower Bound for Choosability of Bipartite Graphs." 30 Oct 2026. https://arxiv.org/abs/2610.42094v1.

Cite this as:

Weisstein, Eric W. "Alon-Krivelevich Conjecture." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/Alon-KrivelevichConjecture.html

Subject classifications