Abstract
We address questions on the existence and structure of universal functions for classes , , with respect to the double Walsh system. It is shown that there exists a measurable set with measure arbitrarily close to , such that, by a proper modification of any integrable function outside , we can get an integrable function , which is universal for each class , , with respect to the double Walsh system in the sense of signs of Fourier coefficients.
Citation
Martin Grigoryan. Artsrun Sargsyan. "On the structure of universal functions for classes , with respect to the double Walsh system." Banach J. Math. Anal. 13 (3) 647 - 674, July 2019. https://doi.org/10.1215/17358787-2019-0015
Information