给出了Banach空间一致凸的一个新的充要条件:设λ,μ∈(0,1),λ+μ=1,f:R+→R+是单调递增且可微的严格凸函数,x是Banach空间,则x是一致凸的当且仅当对任意ε〉0,存在δ〉0,使得当||x||≤1,||x-Y||≥ε时,有 f(λx+μy)〈λf(||x||)+μf(||y||)-δ
A new sufficient and necessary condition is given for uniformly convex Banach spaces. The main result is the following theorem. Theorem Suppose that λ,μ∈(0,1),λ+μ=1,f:R^+→R^+ is a increasing, convex function and X is a Banach space. Then X is uniformly convex if and only if for everye ε〉 0 there existsδ〉0 such that f(||λx+μy||)〈λf(||x||)+μf(||y||)-δ for all ||x||≤1and y∈x satisfying ||x-Y||≥ε