On the maximum degree and order of $K_t$-minor-free graphs with positive Lin--Lu--Yau curvature

Source abstract

Motivated by recent results on the order of connected graphs with positive Lin--Lu--Yau Ricci curvature under forbidden minor or forbidden subgraph conditions and minimum degree assumptions, we prove that, for every integer $t\ge 5$, every connected graph $G$ with no $K_t$ minor, minimum degree at least $t-1$ and positive Lin--Lu--Yau Ricci curvature on every edge satisfies $$Δ(G)=O(t^5\log^{3/2}t) \quad\text{and}\quad |V(G)|<2tΔ(G)^6=O(t^{31}\log^9 t).$$ The minimum degree condition $t-1$ is best possible. Moreover, the bound on the maximum degree $Δ(G)$ extends to locally finite graphs and, consequently, every connected locally finite graph satisfying these conditions is finite.