Cpa空间中的非线性逼近

In this paper, we establish the following Jackson and Bernstein inequalities for C_p^a space:(?)where σ=(α+ (1/p)^-1),α > 0,0 < p < ∞. Moreover, these inequalities are used to give characterizations of the approximation spaces resulted from two approximations verpectively by splines with free knots and approximation by rational functions.