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We construct a basis for free Lie algebras via a ``left-greedy'' bracketing algorithm on Lyndon-Shirshov words. We use a new tool -- the configuration pairing between Lie brackets and graphs of Sinha-Walter -- to show that the left-greedy…

Rings and Algebras · Mathematics 2016-08-31 Benjamin Walter , Aminreza Shiri

Dual canonical bases are expected to satisfy a certain (double) triangularity property by Leclerc's conjecture. We propose an analogous conjecture for common triangular bases of quantum cluster algebras. We show that a weaker form of the…

Quantum Algebra · Mathematics 2020-11-30 Fan Qin

We shall present new characterizations of partially greedy and almost greedy bases. A new class of basis (which we call reverse partially greedy basis) arises naturally from these characterizations of partially greedy bases. We also give…

Functional Analysis · Mathematics 2018-05-18 S. J. Dilworth , Divya Khurana

One classical result in greedy approximation theory is that almost-greedy and semi-greedy bases are equivalent in the context of Schauder bases in Banach spaces with finite cotype. This result was proved by S. J. Dilworth, N. J. Kalton and…

Functional Analysis · Mathematics 2019-03-01 Pablo M. Berná

Our aim is to investigate the properties of existence and uniqueness of greedy bases in Banach spaces. We show the non-existence of greedy basis in some Nakano spaces and Orlicz sequence spaces and produce the first-known examples of…

Functional Analysis · Mathematics 2015-06-01 F. Albiac , J. L. Ansorena , S. J. Dilworth , Denka Kutzarova

It is known that many (upper) cluster algebras possess different kinds of good bases which contain the cluster monomials and are parametrized by the tropical points of cluster Poisson varieties. For a large class of upper cluster algebras…

Representation Theory · Mathematics 2021-07-08 Fan Qin

We continue the study initiated in [F. Albiac and P. Wojtaszczyk, Characterization of $1$-greedy bases, J. Approx. Theory 138 (2006), no. 1, 65-86] of properties related to greedy bases in the case when the constants involved are sharp,…

Functional Analysis · Mathematics 2023-04-13 Fernando Albiac , Jose L. Ansorena , Oscar Blasco , Hung Viet Chu , Timur Oikhberg

An $\alpha$-greedy balanced pair in an ordered set $P=(V,\leq)$ is a pair $(x,y)$ of elements of $V$ such that the proportion of greedy linear extensions of $P$ that put $x$ before $y$ among all greedy linear extensions is in the real…

Combinatorics · Mathematics 2020-10-13 Imed Zaguia

Greedy algorithms are a fundamental category of algorithms in mathematics and computer science, characterized by their iterative, locally optimal decision-making approach, which aims to find global optima. In this review, we will discuss…

Functional Analysis · Mathematics 2024-12-09 Andrea García

We extend based cluster algebras from the finite rank case to the infinite rank case. By extending (quantum) cluster algebras whose initial seeds are associated with signed words (arising from double Bott--Samelson cells), we recover…

Quantum Algebra · Mathematics 2025-11-26 Fan Qin

We show how the existence of a PBW-basis and a large enough central subalgebra can be used to deduce that an algebra is Frobenius. This is done by considering the examples of rational Cherednik algebras, Hecke algebras, quantised universal…

Representation Theory · Mathematics 2008-03-06 K. A. Brown , I. G. Gordon , C. H. Stroppel

We develop and prove the analogs of some results shown in [Berenstein A., Fomin S., Zelevinsky A., Duke Math. J. 126 (2005), 1-52] concerning lower and upper bounds of cluster algebras to the generalized cluster algebras of geometric type.…

Rings and Algebras · Mathematics 2020-09-29 Liqian Bai , Xueqing Chen , Ming Ding , Fan Xu

We show that in case a cluster algebra coincides with its upper cluster algebra and the cluster algebra admits a grading with finite dimensional homogeneous components, the corresponding Berenstein-Zelevinsky quantum cluster algebra can be…

Representation Theory · Mathematics 2020-08-27 Christof Geiß , Bernard Leclerc , Jan Schröer

We give a construction of generalized cluster varieties and generalized cluster scattering diagrams for reciprocal generalized cluster algebras, the latter of which were defined by Chekhov and Shapiro. These constructions are analogous to…

Combinatorics · Mathematics 2022-11-29 Man-Wai Mandy Cheung , Elizabeth Kelley , Gregg Musiker

We prove that if $\mathcal{X}$ is a quasi-greedy Markushevich basis of a Banach space $\mathbb{X}$, its dual basis $\mathcal{X}^*$ spans a norming subspace of $\mathbb{X}^*$. We also prove this result for weaker forms of quasi-greediness,…

Functional Analysis · Mathematics 2025-10-09 Miguel Berasategui

Berenstein and Zelevinsky introduced quantum cluster algebras \cite{BZ1} and the triangular bases \cite{BZ2}. The support conjecture proposed in \cite{LLRZ}, which asserts that the support of each triangular basis element for a rank-2…

Representation Theory · Mathematics 2024-05-15 Li Li

The rate of convergence of the classical Thresholding Greedy Algorithm with respect to bases is studied in this paper. We bound the error of approximation by the product of both norms -- the norm of $f$ and the $A_1$-norm of $f$. We obtain…

Numerical Analysis · Mathematics 2024-07-29 V. N. Temlyakov

We investigate the behavior of a greedy sequence on the sphere $\mathbb{S}^d$ defined so that at each step the point that minimizes the Riesz $s$-energy is added to the existing set of points. We show that for $0<s<d$, the greedy sequence…

Classical Analysis and ODEs · Mathematics 2023-08-01 Dmitriy Bilyk , Michelle Mastrianni , Ryan W. Matzke , Stefan Steinerberger

For the past 25 years, one of the most studied algorithms in the field of Nonlinear Approximation Theory has been the Thresholding Greedy Algorithm. In this paper, we propose new summability methods for this algorithm, generating two new…

Functional Analysis · Mathematics 2025-05-02 Miguel Berasategui , Pablo M. Berná , Stephen J. Dilworth , Denka Kutzarova

In this paper 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 from…

Functional Analysis · Mathematics 2021-06-03 Fernando Albiac , Jose L. Ansorena , Miguel Berasategui , Pablo M. Berna , Silvia Lassalle