On the boundedness of the L1-norm of Walsh–Fejér kernels

Cesàro means with varying parameters of Walsh–Fourier series

“…Applying Abel's transformation twice we get [24]; it even holds sup n K n 1 = 17/15, see [26]) from (3.4) we infer…”

Almost everywhere convergence and divergence of Cesàro means with varying parameters of Walsh–Fourier series

“…Proof of Lemma 2.4 Since (see [13]) sup n K n 1 < 2 from (8) (or even see [15] sup n K n 1 ≤ 17/15), we have sup n∈N T (1)…”

Maximal Operators of Walsh-Nörlund means On the Dyadic Hardy Spaces

“…Yano estimated the value of c and he have c = 2 [27]. Recently, in paper (see [23]) it was shown that the exact value of c is 17 15 .…”