Leonchik E. Yu.
Ukr. Mat. Zh. - 2010. - 62, № 8. - pp. 1145–1148
We obtain an exact estimate for a nonincreasing uniform rearrangement of a function of two variables from the Muckenhoupt class $A_1$.
Ukr. Mat. Zh. - 2003. - 55, № 11. - pp. 1580-1585
We investigate one inequality in approximation theory and obtain necessary and sufficient conditions for the validity of this inequality. We present several examples demonstrating that the results obtained are unimprovable.