@article {Moricz:May :0236-5294:323, author = "Moricz F. and Wade W.R.", title = "AN ANALOGUE OF A THEOREM OF FERENC LUKACS FOR DOUBLE WALSH-FOURIER SERIES", journal = "Acta Mathematica Hungarica", volume = "95", number = "4", year = "May ", abstract = "

A theorem of Ferenc Lukács states that if a periodic function f is integrable in Lebesgue"s sense and has a discontinuity of first kind at some point \alpha, then the nth partial sum of the conjugate series to its trigonometric Fourier series at \alpha divided by \ln n converges to \pi^{-1} \big\{ f(\alpha - 0) - f(\alpha+ 0)\big\} as n\to \infty. An analogue of this theorem for Walsh–Fourier series was proved by Rafat Riad. The main aim of the present paper is to extend the latter result from single to double Wals–Fourier series. We consider also functions of two variables which are of bounded variation over a rectangle in the sense of Hardy and Krause. Among others, we present a proof of the existence of the so-called sector limits of such functions at each point.

", pages = "323-336", url = "http://www.ingentaconnect.com/content/klu/amhu/2002/00000095/00000004/00400437", keyword = "Walsh–Paley system, Walsh series, conjugate Walsh series, rectangular partial sum, bounded variation over a rectangle in the sense of Hardy and Krause, discontinuity of first kind, sector limits of a function of two variables" }