Listar Dpto. Estadística, Informática y Matemáticas - Estatistika, Informatika eta Matematika Saila [desde mayo 2018 / 2018ko maiatzetik] por tema "Quasi-greedy basis"
Mostrando ítems 1-9 de 9
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Bidemocratic bases and their connections with other greedy-type bases
Albiac Alesanco, Fernando José
; Ansorena, José L.; Berasategui, Miguel; Berná, Pablo M.; Lassalle, Silvia (Springer, 2023)
Artículo / Artikulua 
In nonlinear greedy approximation theory, bidemocratic bases have traditionally played the role of dualizing democratic, greedy, quasi-greedy, or almost greedy bases. In this article we shift the viewpoint and study them ... -
Building highly conditional almost greedy and quasi-greedy bases in Banach spaces
Albiac Alesanco, Fernando José ; Ansorena, José L.; Dilworth, S. J.; Kutzarova, Denka (Elsevier, 2019)
Artículo / Artikulua
It is known that for a conditional quasi-greedy basis B in a Banach space X, the associated sequence (k(m)[B](m=1)(infinity) of its conditionality constants verifies the estimate k(m)[B] = O(log m) and that if the reverse ... -
Conditional quasi-greedy bases in non-superreflexive Banach spaces
Albiac Alesanco, Fernando José ; Ansorena, José L.; Wojtaszczyk, Przemyslaw (Springer, 2019)
Artículo / Artikulua
For a conditional quasi-greedy basis B in a Banach space, the associated conditionality constants km[B] verify the estimate km[B]=O(logm). Answering a question raised by Temlyakov, Yang, and Ye, several authors have studied ... -
Democracy of quasi-greedy bases in p-Banach spaces with applications to the efficiency of the thresholding greedy algorithm in the hardy spaces Hp(Dd)
Albiac Alesanco, Fernando José ; Ansorena, José L.; Bello, Glenier (Cambridge University Press, 2023)
Artículo / Artikulua
We use new methods, specific for non-locally convex quasi-Banach spaces, to investigate when the quasi-greedy bases of a -Banach space for 0 < p < p are democratic. The novel techniques we obtain permit to show in particular ... -
Existence of almost greedy bases in mixed-norm sequence and matrix spaces, including besov spaces
Albiac Alesanco, Fernando José ; Ansorena, José L.; Bello, Glenier; Wojtaszczyk, Przemyslaw (Springer, 2023)
Artículo / Artikulua
We prove that the sequence spaces lp ⊕ lq and the spaces of infinite matrices lp(lq ), lq l(p) and ( ∞ n=1 n lp)lq , which are isomorphic to certain Besov spaces, have an almost greedy basis whenever 0 < p < 1 < q < ∞. ... -
Greedy approximation for biorthogonal systems in quasi-Banach spaces
Albiac Alesanco, Fernando José ; Ansorena, José L.; Berná, Pablo M.; Wojtaszczyk, Przemyslaw (Instytut Matematyczny, 2021)
Artículo / Artikulua
The general problem addressed in this work is the development of a systematic study of the thresholding greedy algorithm for general biorthogonal systems in quasi-Banach spaces from a functional-analytic point of view. If ... -
Quasi-greedy bases in ℓp (0 < p < 1) are democratic
Albiac Alesanco, Fernando José ; Ansorena, José L.; Wojtaszczyk, Przemyslaw (Elsevier, 2020)
Artículo / Artikulua
The list of known Banach spaces whose linear geometry determines the (nonlinear) democracy functions of their quasi-greedy bases to the extent that they end up being democratic, reduces to c0, ℓ2, and all separable L1-spaces. ... -
Unconditional and quasi-greedy bases in L-p with applications to Jacobi polynomials Fourier series
Albiac Alesanco, Fernando José ; Ansorena, José L.; Ciaurri, Óscar; Varona, Juan L. (European Mathematical Society, 2019)
Artículo / Artikulua
We show that the decreasing rearrangement of the Fourier series with respect to the Jacobi polynomials for functions in L-p does not converge unless p = 2. As a by-product of our work on quasi-greedy bases in L-p(µ), we ... -
Weak forms of unconditionality of bases in greedy approximation
Albiac Alesanco, Fernando José ; Ansorena, José L.; Berasategui, Miguel; Berná, Pablo M.; Lassalle, Silvia (Instytut Matematyczny, 2022)
Artículo / Artikulua
We study a new class of bases, weaker than quasi-greedy bases, which retain their unconditionality properties and can provide the same optimality for the thresholding greedy algorithm. We measure how far these bases are ...
