Burr–Erdős–Faudree–Rousseau–Schelp conjecture for star forests

Let ss and tt be positive integers. Let n1n2ns1n_{1}\geq n_{2}\geq \cdots\geq n_{s}\geq 1 and m1m2mt1m_{1}\geq m_{2}\geq \cdots\geq m_{t}\geq 1 be integers, and for each k[s+t]\[1]k\in [s+t]\backslash [1] define

k=max{ni+mj1:i+j=k}.\ell_{k}=\max\left\{n_{i}+m_{j}-1:i+j=k\right\}.

Burr–Erdős–Faudree–Rousseau–Schelp conjecture. The size Ramsey number of the two star forests satisfies

r^(i=1sK1,ni,j=1tK1,mj)=k=2s+tk.\hat{r}\left(\bigsqcup_{i=1}^{s}K_{1,n_{i}},\bigsqcup_{j=1}^{t}K_{1,m_{j}}\right)=\sum_{k=2}^{s+t}\ell_{k}.

This conjecture was confirmed for uniform star forests and for several further cases, including when all nin_i and mjm_j are odd or when s=1s=1, but it remains open in general.

Sources & referencesView supporting material

Primary source

Pingting Fu, Zhidan Luo and Zhenyu Ni, “Size Ramsey minimal graphs for uniform star forests”, arXiv:2606.04439 (2026).

Additional references

3 papers in this index state this conjecture (2021–2026). The statement above is taken from the most recent of them; the others are arXiv:2506.10477, arXiv:2111.02065.

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