3 problems

Let $k\geq 1$, let $t_1,\ldots,t_k$ be positive integers, and let … A non-complete graph $G$ is $(K_{t_1},\ldots,K_{t_k})$-co-critical if $G\not\rightarrow(K_{t_1},\ldots,K_{t_k})$…

Hanson and Toft's conjecture. The graph $G$ satisfies

Let $K_{t_1},\ldots,K_{t_r}$ be complete graphs, let $R=R(K_{t_1},\ldots,K_{t_r})$ be their classical Ramsey number, and let $G$ be a $(K_{t_1},\ldots,K_{t_r})$-co-critical graph o…