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We use a cluster ensemble to determine the number of clusters, k, in a group of data. A consensus similarity matrix is formed from the ensemble using multiple algorithms and several values for k. A random walk is induced on the graph…

Machine Learning · Statistics 2014-08-06 Shaina Race , Carl Meyer , Kevin Valakuzhy

We prove that the Grassmannian of totally isotropic $k$-spaces of the polar space associated to the unitary group $\mathsf{SU}_{2n}(\mathbb{F})$ ($n\in \mathbb{N}$) has generating rank ${2n\choose k}$ when $\mathbb{F}\ne \mathbb{F}_4$. We…

Combinatorics · Mathematics 2010-10-04 Rieuwert J. Blok , Bruce N. Cooperstein

We show that a certain orbit category considerd by Keller encodes the combinatorics of the $m$-clusters of Fomin and Reading in a fashion similar to the way the cluster category of Buan, Marsh, Reineke, Reiten, and Todorov encodes the…

Representation Theory · Mathematics 2007-09-10 Hugh Thomas

Geiss, Leclerc and Schr\"oer introduced a class of 1-Iwanaga-Gorenstein algebras $H$ associated to symmetrizable Cartan matrices with acyclic orientations, generalizing the path algebras of acyclic quivers. They also proved that…

Representation Theory · Mathematics 2025-12-11 Lang Mou , Xiuping Su

The morphology of galaxy clusters is quantified using Minkowski functionals, especially the vector-valued ones, which contain directional information and are related to curvature centroids. The asymmetry of clusters and the amount of their…

Astrophysics · Physics 2007-05-23 Claus Beisbart , Thomas Buchert

We propose a conjectural semiorthogonal decomposition for the derived category of the moduli space of stable rank 2 bundles with fixed determinant of odd degree, independently formulated by Narasimhan. We discuss some evidence for, and…

Algebraic Geometry · Mathematics 2023-03-14 Pieter Belmans , Sergey Galkin , Swarnava Mukhopadhyay

In this paper we study the mod $2$ cohomology ring of the Grasmannian $\widetilde{G}_{n,3}$ of oriented $3$-planes in $\mathbb{R}^n$. We determine the degrees of the indecomposable elements in the cohomology ring. We also obtain an almost…

Algebraic Topology · Mathematics 2019-07-16 Somnath Basu , Prateep Chakraborty

We pursue a classification of low-rank super-modular categories parallel to that of modular categories. We classify all super-modular categories up to rank=$6$, and spin modular categories up to rank=$11$. In particular, we show that, up to…

Quantum Algebra · Mathematics 2018-11-01 Paul Bruillard , César Galindo , Siu-Hung Ng , Julia Yael Plavnik , Eric C. Rowell , Zhenghan Wang

This paper explores the cluster algebra structure of the moduli space $\mathscr{A}_{\mathrm{SL}_{n+1},\mathbb{S}}$ of twisted $\mathrm{SL}_{n+1}$-local systems on a surface. We derive general recurrence relations for cluster variables…

Combinatorics · Mathematics 2026-02-27 Vu Tung Lam Dinh , Ivan Chi-Ho Ip

A equivalence relation, preserving the Chern-Weil form, is defined between connections on a complex vector bundle. Bundles equipped with such an equivalence class are called Structured Bundles, and their isomorphism classes form an abelian…

Algebraic Topology · Mathematics 2008-10-29 James Simons , Dennis Sullivan

Two natural and widely used representations for the community structure of networks are clusterings, which partition the vertex set into disjoint subsets, and layouts, which assign the vertices to positions in a metric space. This paper…

Discrete Mathematics · Computer Science 2009-02-06 Andreas Noack

For a given cluster-tilted algebra $A$ of tame type, it is proved that different indecomposable $\tau$-rigid $A$-modules have different dimension vectors. This is motivated by Fomin-Zelevinsky's denominator conjecture for cluster algebras.…

Rings and Algebras · Mathematics 2024-02-15 Changjian Fu , Shengfei Geng

Clustering, assortativity, and communities are key features of complex networks. We probe dependencies between these attributes and find that ensembles with strong clustering display both high assortativity by degree and prominent community…

Physics and Society · Physics 2013-05-29 David V. Foster , Jacob G. Foster , Peter Grassberger , Maya Paczuski

We introduce a family of cluster algebras of infinite rank associated with root systems of type $A$, $D$, $E$. We show that suitable completions of these cluster algebras are isomorphic to the Grothendieck rings of the categories…

Quantum Algebra · Mathematics 2024-10-30 Christof Geiss , David Hernandez , Bernard Leclerc

We introduce analogues of Soergel bimodules for complex reflection groups of rank one. We give an explicit parametrization of the indecomposable objects of the resulting category and give a presentation of its split Grothendieck ring by…

Representation Theory · Mathematics 2018-12-07 Thomas Gobet , Anne-Laure Thiel

Usual formulations of the clustering coefficient can be shown to be insufficient in the task of describing the local topology of very simple networks. Motivated by this, we review some alternatives in order to present an extension, the…

Data Analysis, Statistics and Probability · Physics 2007-05-23 Alexandre H. Abdo , A. P. S. de Moura

We describe the fundamental group and second homotopy group of ordered $k-$point sets in $Gr(k,n)$ generating a subspace of fixed dimension.

Group Theory · Mathematics 2013-11-25 Sandro Manfredini , Simona Settepanella

In this work, the possibility of clustering correlated random variables was examined, both because of their mutual similarity and because of their similarity to the principal components. The k-means algorithm and spectral algorithms were…

Machine Learning · Computer Science 2019-09-10 Zenon Gniazdowski , Dawid Kaliszewski

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 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