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This is a brief and informal introduction to cluster algebras. It roughly follows the historical path of their discovery, made jointly with A.Zelevinsky. Total positivity serves as the main motivation.

Rings and Algebras · Mathematics 2010-05-18 Sergey Fomin

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 $L_{p}(\mu)$, we show that no…

Functional Analysis · Mathematics 2015-07-22 Fernando Albiac , José L. Ansorena , Óscar Ciaurri , Juan L. Varona

The article concerns the existence and uniqueness of quantisations of cluster algebras. We prove that cluster algebras with an initial exchange matrix of full rank admit a quantisation in the sense of Berenstein-Zelevinsky and give an…

Quantum Algebra · Mathematics 2017-09-11 Florian Gellert , Philipp Lampe

In this paper we study fundamental model-theoretic questions for free associative algebras, namely, first-order classification, decidability of the first-order theory, and definability of the set of free bases. We show that two free…

Logic · Mathematics 2018-08-16 Olga Kharlampovich , Alexei Myasnikov

For the cluster category of a hereditary or a canonical algebra, equivalently for the cluster category of the hereditary category of coherent sheaves on a weighted projective line, we study the Grothendieck group with respect to an…

Representation Theory · Mathematics 2020-09-28 Michael Barot , Dirk Kussin , Helmut Lenzing

Partially greedy bases in Banach spaces were introduced by Dilworth et al. as a strictly weaker notion than the (almost) greedy bases. In this paper, we study two natural ways to strengthen the definition of partial greediness. The first…

Functional Analysis · Mathematics 2023-02-07 Miguel Berasategui , Pablo M. Berná , Hung Viet Chu

Fomin-Zelevinsky conjectured that in any cluster algebra, the cluster monomials are linearly independent and that the exchange graph and cluster complex are independent of the choice of coefficients. We confirm these conjectures for all…

Representation Theory · Mathematics 2013-03-05 Giovanni Cerulli Irelli , Bernhard Keller , Daniel Labardini-Fragoso , Pierre-Guy Plamondon

We consider some bases in the Hecke algebra and exhibit certain dualities between them.

Combinatorics · Mathematics 2011-01-11 Rahbar Virk

We prove the full Fock--Goncharov conjecture for $\mathcal{A}_{SL_2,\Sigma_{g,p}}$, the $\mathcal{A}$-cluster variety of the moduli of decorated twisted $SL_2$-local systems on triangulable surfaces $\Sigma_{g,p}$ with at least 2 punctures.…

Commutative Algebra · Mathematics 2025-12-29 Enhan Li

The canonical bases of cluster algebras of finite types and rank 2 are given explicitly in \cite{CK2005} and \cite{SZ} respectively. In this paper, we will deduce $\mathbb{Z}$-bases for cluster algebras for affine types…

Representation Theory · Mathematics 2008-12-15 Ming Ding , Jie Xiao , Fan Xu

In this paper we introduce a new approach for organizing algebras of global dimension at most 2. We introduce the notion of cluster equivalence for these algebras, based on whether their generalized cluster categories are equivalent. We are…

Representation Theory · Mathematics 2012-03-08 Claire Amiot , Steffen Oppermann

Geiss-Leclerc-Schroer defined the cluster algebra structure on the coordinate ring $C[N(w)]$ of the unipotent subgroup, associated with a Weyl group element $w$ and they proved cluster monomials are contained in Lusztig's dual semicanonical…

Quantum Algebra · Mathematics 2015-01-14 Yoshiyuki Kimura

We investigate various aspects of the "weighted" greedy algorithm with respect to a Schauder basis. For a weight w, we describe w-greedy, w-almost-greedy and w-partially-greedy bases, and show some properties of w-semi-greedy bases. To…

Functional Analysis · Mathematics 2018-06-19 P. M. Berná , S. J. Dilworth , D. Kutzarova , T. Oikhberg , B. Wallis

We introduce the notion of a \textit{weight-almost greedy} basis and show that a basis for a real Banach space is $w$-almost greedy if and only if it is both quasi-greedy and $w$-democratic. We also introduce the notion of…

Functional Analysis · Mathematics 2018-03-09 Stephen J. Dilworth , Denka Kutzarova , Vladimir Temlyakov , Ben Wallis

We continue our study of the Thresholding Greedy Algorithm when we restrict the vectors involved in our approximations so that they either are supported on intervals of $\mathbb N$ or have constant coefficients. We introduce and…

Functional Analysis · Mathematics 2023-02-14 Miguel Berasategui , Pablo M. Berná , Hung Viet Chu

We show that non of the spaces $(\bigoplus_{n=1}^\infty\ell_p)_{\ell_q}$, $1\le p\not= q<\infty$, have a greedy basis. This solves a problem raised by Dilworth, Freeman, Odell and Schlumprect. Similarly, the spaces…

Functional Analysis · Mathematics 2013-10-10 Gideon Schechtman

We consider the quantum cluster algebras which are injective-reachable and introduce a triangular basis in every seed. We prove that, under some initial conditions, there exists a unique common triangular basis with respect to all seeds.…

Quantum Algebra · Mathematics 2017-10-18 Fan Qin

This article closes the cycle of characterizations of greedy-like bases in the isometric case initiated in [F. Albiac and P. Wojtaszczyk, Characterization of $1$-greedy bases, J. Approx. Theory 138 (2006)] with the characterization of…

Functional Analysis · Mathematics 2015-08-18 F. Albiac , J. L. Ansorena

Tevelev has given a remarkable explicit formula for the discriminant of a complex simple Lie algebra, which can be defined as the equation of the dual hypersurface of the minimal nilpotent orbit, or of the so-called adjoint variety. In this…

Algebraic Geometry · Mathematics 2022-04-06 Vladimiro Benedetti , Laurent Manivel

We first study a new family of graded quiver varieties together with a new $t$-deformation of the associated Grothendieck rings. This provides the geometric foundations for a joint paper by Yoshiyuki Kimura and the author. We further…

Quantum Algebra · Mathematics 2016-06-22 Fan Qin
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