the National Natural Science Foundation of China (No. 10571040); the Natural Science Foundation of Hebei Province (No. A2004000137); the Doctorial Fund of Education Department of Hebei Province (No. B2004118); the Doctorial Fund of Hebei Normal University (No. L2003B04).
In this paper, we obtain the strong converse inequality for Száisz operators with K-functional by introducing a new K-functional of the formKλ^α(f,t^2) =inf g∈Cλ^2{‖f -g‖o +t^2‖g‖2} (0 ≤ λ≤ 1,0 ≤α ...