On the asymptotic behavior of online Ramsey numbers for stars, paths and cycles
This provides the first asymptotic results for online Ramsey numbers involving paths and cycles, advancing the understanding of online Ramsey theory for graph families.
The paper determines the asymptotic behavior of online Ramsey numbers for paths, cycles, and stars, showing that for fixed k, the ratios of these numbers to n converge to constants.
The online Ramsey game for graphs $G$ and $H$ is played on the infinite complete graph $K_\mathbb{N}$. Each round, Builder chooses an edge, and Painter colors it red or blue. The online Ramsey number $\tilde{r}(G,H)$ is the smallest integer $t$ for which Builder has a strategy that guarantees a red copy of $G$ or a blue copy of $H$ in at most $t$ rounds. We show that for every fixed $k$, there are constants $λ_1$ and $λ_2$ such that $\tilde{r}(P_k,P_n)/n$ and $\tilde{r}(P_k,C_n)/n$ converge to $λ_1$, and $\tilde{r}(K_{1,k},P_n)/n$ and $\tilde{r}(K_{1,k},C_n)/n$ converge to $λ_2$.