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ABSTRACT. An extension of the Bojanic-Stanojevic type inequality [1] is
made by considering the -th derivate of the Dirichlet's kernel
instead of .
Namely, the following inequality is proved:
where
is the -norm, {} is a sequence of real numbers,
,
and is
an absolute constant dependent only on . As an application of this
inequality, it is shown that the class is a subclass of
, where is the extension of
the Fomin's class, is the extension of the
Garrett-Stanojevic class [8] and
is the class of all
null sequences of bounded variation.
[1] R. BOJANIC and C.V.
STANOJEVIC, A class of L1-convergence, Trans. Amer. Math.
Soc., 269 (1982), 677-683.
[8] Z. TOMOVSKI, An extension of the Garrett- Stanojevic class, Approx.
Theory Appl., 16(1) (2000) 46–51. [ONLINE] A corrected version is
available in the RGMIA Research Report Collection, 3(4), Article
3, 2000. URL: http://rgmia.vu.edu.au/v3n4.html
Key words:
Bojanic-Stanojevic inequality, Sidon-Fomin's
inequality, Bernstein's
inequality,
L1-convergence,
cosine series.
2000 Mathematics Subject
Classification: 26D15,
42A20.
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