Coloring Small $K_t$-Minor-Free Graphs

Abstract

Delcourt and Postle proved that every $K_t$-minor-free graph is $O(t\log\log t)$-colorable and reduced the Linear Hadwiger Conjecture to coloring $K_t$-minor-free graphs on $O(t\log^4 t)$ vertices. In this paper, we use the star contraction technique to improve their bound for small graphs and use their reduction to extend this improvement to all $K_t$-minor-free graphs. Thus we improve their $O(t\log\log t)$ bound to $O(t\sqrt{\log\log t})$.