Browsing Artículos de revista DEIM - EIMS Aldizkari artikuluak by UPNA Author "Albiac Alesanco, Fernando José"
Now showing items 21-28 of 28
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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. ... -
Sparse approximation using new greedy-like bases in superreflexive spaces
Albiac Alesanco, Fernando José ; Ansorena, José L.; Berasategui, Miguel (Instytut Matematyczny, 2023)
Artículo / Artikulua
This paper is devoted to theoretical aspects of optimality of sparse approximation. We undertake a quantitative study of new types of greedy-like bases that have recently arisen in the context of non-linear m-term approximation ... -
Structure of the Lipschitz free p-spaces Fp(Zd) and Fp(Rd) for 0 < p ≤ 1
Albiac Alesanco, Fernando José ; Ansorena, José L.; Cúth, Marek; Doucha, Michal (Springer, 2021)
Artículo / Artikulua
Our aim in this article is to contribute to the theory of Lipschitz free p-spaces for 0 < p ≤ 1 over the Euclidean spaces Rd and Zd. To that end, on one hand we show that Fp(Rd) admits a Schauder basis for every p ∈ 2 (0, ... -
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 ... -
Uniqueness of unconditional basis of Hp(T) ⊕ 2 and Hp(T) ⊕ T (2) for 0 < p < 1
Albiac Alesanco, Fernando José ; Ansorena, José L.; Wojtaszczyk, Przemyslaw (Elsevier, 2022)
Artículo / Artikulua
Our goal in this paper is to advance the state of the art of the topic of uniqueness of unconditional basis. To that end we establish general conditions on a pair (X, Y) formed by a quasi-Banach space X and a Banach ... -
Uniqueness of unconditional basis of infinite direct sums of quasi-Banach spaces
Albiac Alesanco, Fernando José ; Ansorena, José L. (Kluwer Academic Publishers, 2022)
Artículo / Artikulua
This paper is devoted to providing a unifying approach to the study of the uniqueness of unconditional bases, up to equivalence and permutation, of infinite direct sums of quasi-Banach spaces. Our new approach to this type ... -
Uniqueness of unconditional basis of ℓ2⊕T(2)
Albiac Alesanco, Fernando José ; Ansorena, José L. (American Mathematical Society, 2022)
Artículo / Artikulua
We provide a new extension of Pitt’s theorem for compact operators between quasi-Banach lattices which permits to describe unconditional bases of finite direct sums of Banach spaces X1 · · · Xn as direct sums of unconditional ... -
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 ...
