摘要

Let G(V, E) be an infinite (locally finite) graph. In this paper we prove that if G satisfies the CDE(m,-K)-condition for some m > 0, K >= 0, and u : V -> R is a positive solution to the following equation Delta(mu)u = -lambda u, then lambda <= mK/2 and u satisfies a gradient estimate, which is parallel to the results on complete noncompact Riemannian manifolds established by Li (Geometric analysis. Cambridge studies in advanced mathematics, Cambridge University Press, Cambridge, 2012), and on smooth metric measure spaces established by Wang (Ann Glob Anal Geom 37: 393-402, 2010). As byproducts, we also get two Liouville theorems and a Harnack inequality.