Conjectured exact value of the Ramsey number of a book graph versus an odd cycle

From papers

Let BnB_n denote the book graph with nn pages and let CmC_m denote the cycle of odd length mm. The Ramsey number R(Bn,Cm)R(B_n,C_m) is the least integer such that every red-blue edge-colouring of a complete graph of that order contains a red copy of BnB_n or a blue copy of CmC_m.

The authors' conjecture. For each integer n3493n\geq 3493, if n2m+499n\geq 2m+499 and m7m\geq 7 is an odd integer, then

R(Bn,Cm)=2n+3.R(B_n,C_m)=2n+3.

The paper presents this as a conjecture motivated by the lower bound and notes that an earlier theorem partially confirms it for larger values of nn. The authors also state that they proved the analogous claim for the subgraph K2,n\mathbb{K}_{2,n} of BnB_n; the exact Ramsey-number assertion remains open in the supplied text.

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Sources & referencesView supporting material

Primary source

Sayan Gupta, “A study of two Ramsey numbers involving odd cycles”, arXiv:2504.15693 (2025).

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