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Two Korovkin-type theorems in multivariate approximation. (English) Zbl 1155.41008
Two Korovkin-type theorems [{\it F. Altomare} and {\it 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 {\it H. Wang} [J. Approximation Theory 132, No. 2, 258--264 (2005; Zbl 1118.41015)].

41A55Approximate quadratures
41A80Remainders in approximation formulas
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