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Abstract
Abstract
The aim of this paper is to prove that for an arbitrary set of measure zero there exists a bounded function for which the Fejér means of the Walsh-Fourier series of the function diverge.
Abstract
The main aim of this paper is to prove that there exists a martingale f ∈ H 1 2/▭ such that the restricted maximal operators of Fejér means of twodimensional Walsh-Fourier series and conjugate Walsh-Fourier series does not belong to the space weak-L 1/2.
In this paper we study the exponential uniform strong approximation of two-dimensional Walsh-Fourier series. In particular, it is proved that the two-dimensional Walsh-Fourier series of the continuous function f is uniformly strong summable to the function f exponentially in the power 1/2. Moreover, it is proved that this result is best possible.
In this paper we characterize the set of convergence of the Marcinkiewicz-Fejér means of two-dimensional Walsh-Fourier series.
References [1] Fine , N.J. 1949 On Walsh functions Trans. Amer. Math. Soc. 65 372 – 414 10
1 Introduction A system formed by Walsh functions is an orthonormal system which takes only values 1 and −1. This property, which is why the Walsh system was considered to be an “artificial” orthonormal system by many mathematicians in 1923, the
, 7 ( 2 ): 141 – 150 , 1981 . [37] A . Šne˘ıder . On series of Walsh functions with monotonic coefficients . Izvestiya Akad. Nauk SSSR. Ser. Mat . 12 : 179 – 192 , 1948 . (In Russian.) [38] G . Tephnadze . On the maximal operators of Kaczmarz