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The aim of this note is to describe a geometric relation between simple plane curve singularities classified by simply laced Cartan matrices and cluster varieties of finite type also classified by the simply laced Cartan matrices. We…

Algebraic Geometry · Mathematics 2024-03-14 Vladimir Fock

Considered as commutative algebras, cluster algebras can be very unpleasant objects. However, the first author introduced a condition known as "local acyclicity" which implies that cluster algebras behave reasonably. One of the earliest and…

Combinatorics · Mathematics 2015-06-23 Greg Muller , David E. Speyer

We initiate a systematic study of the cohomology of cluster varieties. We introduce the Louise property for cluster algebras that holds for all acyclic cluster algebras, and for most cluster algebras arising from marked surfaces. For…

Algebraic Geometry · Mathematics 2022-03-09 Thomas Lam , David E. Speyer

We propose a novel graph clustering method guided by additional information on the underlying structure of the clusters (or communities). The problem is formulated as the matching of a graph to a template with smaller dimension, hence…

Machine Learning · Statistics 2021-07-06 Mateus Riva , Florian Yger , Pietro Gori , Roberto M. Cesar , Isabelle Bloch

We define Enriques varieties as a higher dimensional generalization of Enriques surfaces and construct examples by using fixed point free automorphisms on generalized Kummer varieties. We also classify all automorphisms of generalized…

Algebraic Geometry · Mathematics 2010-11-16 Samuel Boissiere , Marc Nieper-Wisskirchen , Alessandra Sarti

We develop hard clustering based on likelihood rather than distance and prove convergence. We also provide simulations and real data examples.

Machine Learning · Statistics 2024-09-12 Zuogong Yue , Victor Solo

In 2016, Leclerc constructed conjectural cluster structures on open Richardson varieties using representations of preprojective algebras. A variant with more explicit seeds was obtained by M\'enard in his thesis. We show that M\'enard's…

Representation Theory · Mathematics 2022-07-22 Peigen Cao , Bernhard Keller

We consider several hill-climbing approaches to clustering as formulated by Fukunaga and Hostetler in the 1970's. We study both continuous-space and discrete-space (i.e., medoid) variants and establish their consistency.

Statistics Theory · Mathematics 2022-02-21 Ery Arias-Castro , Wanli Qiao

We investigate the internal structure of clusters of galaxies in high-resolution N-body simulations of 4 different cosmologies. There is a higher proportion of disordered clusters in critical-density than in low-density universes, although…

Cluster varieties are geometric objects that have recently found applications in several areas of mathematics and mathematical physics. This thesis studies the geometry of a large class of cluster varieties associated to compact oriented…

Algebraic Geometry · Mathematics 2018-12-27 Dylan G. L. Allegretti

In this paper we first study clusters in type $\tilde{\mathbb{A}}$ by collecting them into a finite number of infinite families given by Dehn twists of their corresponding triangulations, and show that these families are counted by the…

Representation Theory · Mathematics 2023-06-13 Kiyoshi Igusa , Ray Maresca

To solve a number of problems on varieties of groups, stated by Kleiman, Kuznetsov, Ol'shanskii, Shmel'kin in the 1970's and 1980's, we construct continuously many varieties of groups in which all periodic groups are abelian and whose…

Group Theory · Mathematics 2007-05-23 S. V. Ivanov , A. M. Storozhev

We introduce a cohomology, called extendable cohomology, for abstract complex singular varieties based on suitable differential forms. Beside a study of the general properties of such a cohomology, we show that, given a complex vector…

Complex Variables · Mathematics 2008-12-04 Carlo Perrone

We introduce ordered and unordered configuration spaces of 'clusters' of points in an Euclidean space $\mathbb{R}^d$, where points in each cluster satisfy a 'verticality' condition, depending on a decomposition $d=p+q$. We compute the…

Algebraic Topology · Mathematics 2022-05-03 Andrea Bianchi , Florian Kranhold

We develop a general theory for estimating the probability that a galaxy cluster of a given shape exists. The theory is based on the observed result that the distribution of galaxies is very close to quasi-equilibrium, in both its linear…

Cosmology and Nongalactic Astrophysics · Physics 2012-01-11 Abel Yang , William C. Saslaw

We study the cluster categories arising from marked surfaces (with punctures and non-empty boundaries). By constructing skewed-gentle algebras, we show that there is a bijection between tagged curves and string objects. Applications include…

Representation Theory · Mathematics 2019-02-20 Yu Qiu , Yu Zhou

The cluster automorphism group of a cluster variety was defined by Gekhtman--Shapiro--Vainshtein, and later studied by Lam--Speyer. Braid varieties are interesting affine algebraic varieties indexed by positive braid words. It was proved…

Combinatorics · Mathematics 2026-05-26 Soyeon Kim

Cluster categories were introduced in 2006 by Buan-Marsh-Reineke-Reiten-Todorov in order to categorify acyclic cluster algebras without coefficients. Their construction was generalized by Amiot (2009) and Plamondon (2011) to arbitrary…

Representation Theory · Mathematics 2023-04-11 Yilin Wu

We study complex Dirac structures, that is, Dirac structures in the complexified generalized tangent bundle. These include presymplectic foliations, transverse holomorphic structures, CR-related geometries and generalized complex…

Differential Geometry · Mathematics 2023-12-19 Dan Aguero , Roberto Rubio

In the present paper we examine the relationship between several type $A$ cluster theories and structures. We define a 2D geometric model of a cluster theory, which generalizes cluster algebras from surfaces, and encode several existing…

Representation Theory · Mathematics 2022-01-03 Job Daisie Rock