\limsup_{x\to_v{\bar{x}}}f^{\partial}(x;u+\alpha ({\bar{x}}-x))<\lambda$$ and show that $\lambda$ is greater than or equal to the left-hand side of .  From we can find $\delta>0$ such that $$\label{formula00} x\in D({\bar{x}}, v,\delta) \Rightarrow 