Abstract. The author extends some results of Z. Ditzian and S. Tikhonov in [3] to the case of functions defined on bounded and unbounded domains with inner singularities.

AMS Subject Classification (1991): 41A17; 41A10; 18E20

Keyword(s): embedding theorems, polynomial inequalities, moduli of smoothness, best approximation

Received September 2, 2008, and in revised form November 18, 2008. (Registered under 6428/2009.)