Classical Kantorovich operators revisited

The main object of this paper is to improve some of the known estimates for classical Kantorovich operators. A quantitative Voronovskaya-type result in terms of second moduli of continuity which improves some previous results is obtained. In order to explain non-multiplicativity of the Kantorovich operators a Chebyshev-Gr"uss inequality is given. Two Gr"uss-Voronovskaya theorems for Kantorovich operators are considered as well.