A note on forcing triples with no forcing pairs

Abstract

Chung, Graham and Wilson defined a set of graphs $\mathcal{H}$ to be forcing, if any sequence of graphs $\{G_n\}_{n \geq 0}$ with $|G_n| = n$ must be quasirandom, whenever $hom(H, G_n)= (p^{|E(H)|}+o(1))n^{|V(H)|}$ for every $H \in \mathcal{H}$ and some constant $p \in (0, 1)$. Answering a question of Horn, attributed to Graham, a forcing set of three graphs is constructed such that no two of the three graphs are forcing as a pair.