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The non-equivalence between the trigonometric system and the system of functions with pointwise restrictions on values in the uniform and L1 norms

Published online by Cambridge University Press:  15 March 2011

MICHAŁ WOJCIECHOWSKI*
Affiliation:
Institute of Mathematics, Polish Academy of Sciences, Sniadeckich 8, I p., 00-956 Warszawa, Poland. e-mail: miwoj-impan@o2.pl

Extract

Let n denote the space of trigonometric polynomials of degree n i.e. n = span(eikt : |k| ≤ n) ⊂ Lp() and let (Ω, dx) be any mesurable space with finite measure. In this paper we use the quantitative version of the Helson-Rudin-Cohen idempotent theorem due to Green and Sanders (cf. [3]) to prove the following.

Type
Research Article
Copyright
Copyright © Cambridge Philosophical Society 2011

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References

REFERENCES

[1]Abramovich, Y. A. and Aliprantis, C. D. Positive operators, in: Handbook of the Geometry of Banach Spaces, edited by Johnson, W. B. and Lindenstrauss, J. (Elsevier 2001), 85122.CrossRefGoogle Scholar
[2]Dechamps, M. Sous-espaces invariants de L p(G), G groupe ablien compact, Harmonic analysis, Exp. No. 3. Publ. Math. Orsay 81, 8, Univ. Paris XI, Orsay, (1981).Google Scholar
[3]Green, B. and Sanders, T.A quantitative version of the idempotent theorem in harmonic analysis. Ann. of Math. 168 (2008), 10251054.CrossRefGoogle Scholar
[4]Helson, H.Note of harmonic functions. Proc. Amer. Math. Soc. 4 (1953), 686691.CrossRefGoogle Scholar
[5]Helson, H.On a theorem of Szegö. Proc. Amer. Math. Soc. 6 (1955), 235242.Google Scholar
[6]Konyagin, S.V.On a problem of Littlewood. Math. USSR Izv. 18 2 (1982), 205225; Izv. Akad. Nauk SSSR 45 (1981), 243–265.CrossRefGoogle Scholar
[7]McGehee, O.C., Pigno, L. and Smith, B.Hardy's inequality and the norm for exponential sums. Ann. of Math. 113 (1981), 613618.CrossRefGoogle Scholar
[8]Meyer, Y.Endomorphismes des idéaux fermés de L 1(G), classes de Hardy et séries de Fourier lacunaires Ann. Sci. École Norm. 1 (4) (1968).Google Scholar
[9]Pelczynski, A. Selected problems on the structre of complemented subspaces of Banach spaces, in: Methods in Banach Spaces, edited by Castillo, Jesus M. F. and Johnson, William B., London Mathematical Society Lecture Note Series 337, Cambridge University Press (2006), 341354.CrossRefGoogle Scholar