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Two Korovkin-type theorems in multivariate approximation. (English) Zbl 1155.41008
Two Korovkin-type theorems [F. Altomare and M. Campiti, Korovkin-type Approximation Theory and its applications. de Gruyter Studies in Mathematics. 17. (Berlin): Walter de Gruyter. (1994; Zbl 0924.41001)] in multivariate approximation in which the limit of the sequence of operators is not necessarily the identity have been proved. One of these is an analogue of a result proved in H. Wang [J. Approximation Theory 132, No. 2, 258–264 (2005; Zbl 1118.41015)].
MSC:
41A55Approximate quadratures
41A80Remainders in approximation formulas