On the Vertex Folkman Numbers $F_v(2,...,2;q)$

Abstract

For a graph $G$ the symbol $G\tov(a_1,...,a_r)$ means that in every $r$-coloring of the vertices of $G$ for some $i\in\{1,...,r\}$ there exists a monochromatic $a_i$-clique of color $i$. The vertex Folkman numbers \[ \FN=\min\{|V(G)|:G\tov(a_1,...,a_r)\text{and}K_q\nsubseteqq G\} \] are considered. In this paper we shall compute the Folkman numbers $F_v(\underbrace{2,...,2}_r;r-k+1)$ when $k\le 12$ and $r$ is sufficiently large. We prove also new bounds for some vertex and edge Folkman numbers.