Lu et al.'s odd-cycle Cartesian product conjecture

Let CrC_r denote the cycle on rr vertices. Lu et al.'s conjecture. For positive integers m,nm,n,

χℓ(C2m+1□C2n+1)=3.\chi_\ell(C_{2m+1}\Box C_{2n+1})=3.

The supplied text establishes the corresponding values for products involving even cycles but says that the list chromatic number for two odd cycles remains unresolved.

References

Primary source

Nandana K Vasudevan, K Somasundaram and N Narayanan, “List-Coloring and Chromatic-Choosability – A Dynamic Survey”, arXiv:2606.31702 (2026).

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