Problem 564 — Visual explainer (undergrad) ========================================== Problem statement --------------- Let $R_3(n)$ be the minimal $m$ such that if the edges of the $3$-uniform hypergraph on $m$ vertices are $2$-coloured then there is a monochromatic copy of the complete $3$-uniform hypergraph on $n$ vertices.Is there some constant $c>0$ such that\[R_3(n) \geq 2^{2^{cn}}?\] Picture ------- Graph picture: o---o |\ | | \ | o---o K4 is the complete graph on 4 vertices (all connections) Question: what to look at ------------------------ - Restate the problem as: given the constraint, what asymptotic bound or structure must follow? - Use the comments as benchmarks (best known bounds / constructions). Context ------- Area hint: infinite graph theory / Ramsey-type decompositions. Benchmarks / known results (from comments) ---------------------------------------- - A problem of Erd\H{o}s, Hajnal, and Rado, who prove the bounds\[2^{cn^2}< R_3(n)< 2^{2^{n}}\]for some constant $c>0$. - Erd\H{o}s, Hajnal, M\'{a}t\'{e}, and Rado have proved a doubly exponential lower bound for the corresponding problem with $4$ colours.