The Approximation Qualities For The Iterated Boolean Sums Of The Two-dimensional Bernstein-Kantorovich Operators

The aim of this paper is to study the approximation properties of the iteratedBoolean sums of two-dimensional Bernstein-Kantorovich operators．Firstly we give thedefinition of the iterated Boolean sums,K-functional and the differential operatorsP(D)respectively；Secondly we will use K-fuctional to discuss the direct,inverse andequivalent theorems on the iterated Boolean sums (?)~rK_nf．These results generalize someprevious ones．...