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The two-point correlation function has been the standard statistic for quantifying how galaxies are clustered. The statistic uses the positions of galaxies, but not their properties. Clustering as a function of galaxy property, be it type,…

Astrophysics · Physics 2007-05-23 Ravi K. Sheth , Andrew J. Connolly , Ramin Skibba

Networks (or graphs) appear as dominant structures in diverse domains, including sociology, biology, neuroscience and computer science. In most of the aforementioned cases graphs are directed - in the sense that there is directionality on…

Social and Information Networks · Computer Science 2015-06-16 Fragkiskos D. Malliaros , Michalis Vazirgiannis

Spectral clustering is a popular unsupervised learning technique which is able to partition unlabelled data into disjoint clusters of distinct shapes. However, the data under consideration are often experimental data, implying that the data…

Machine Learning · Statistics 2025-05-26 Jürgen Dölz , Jolanda Weygandt

A new clustering accuracy measure is proposed to determine the unknown number of clusters and to assess the quality of clustering of a data set given in any dimensional space. Our validity index applies the classical nonparametric…

Methodology · Statistics 2022-02-15 Soumita Modak

We develop a network in which the natural numbers are the vertices. We use the decomposition of natural numbers by prime numbers to establish the connections. We perform data collapse and show that the degree distribution of these networks…

Statistical Mechanics · Physics 2009-11-10 Gilberto Corso

A relational dataset is often analyzed by optimally assigning a label to each element through clustering or ordering. While similar characterizations of a dataset would be achieved by both clustering and ordering methods, the former has…

Machine Learning · Computer Science 2023-04-10 Tatsuro Kawamoto , Masaki Ochi , Teruyoshi Kobayashi

The analysis of the presence of substructures in 16 well-sampled clusters of galaxies suggests a stimulating hypothesis: Clusters could be classified as unimodal or bimodal, on the basis of to the sub-clump distribution in the {\em 3-D}…

Astrophysics · Physics 2009-10-22 E. Escalera , A. Biviano , M. Girardi , G. Giuricin , F. Mardirossian , A. Mazure , M. Mezzetti

A statistical description of heavy particles suspended in incompressible rough self-similar flows is developed. It is shown that, differently from smooth flows, particles do not form fractal clusters. They rather distribute inhomogeneously…

Chaotic Dynamics · Physics 2007-05-23 J. Bec , M. Cencini , R. Hillerbrand

Measuring graph clustering quality remains an open problem. To address it, we introduce quality measures based on comparisons of intra- and inter-cluster densities, an accompanying statistical test of the significance of their differences…

Social and Information Networks · Computer Science 2020-03-20 Pierre Miasnikof , Alexander Y. Shestopaloff , Anthony J. Bonner , Yuri Lawryshyn , Panos M. Pardalos

Traditional clustering identifies groups of objects that share certain qualities. Tangles do the converse: they identify groups of qualities that often occur together. They can thereby discover, relate, and structure types: of behaviour,…

Artificial Intelligence · Computer Science 2024-05-15 Reinhard Diestel

By the method of Poissonization we confirm some existing results concerning consistent estimation of the structural distribution function in the situation of a large number of rare events. Inconsistency of the so called natural estimator is…

Statistics Theory · Mathematics 2007-06-13 Bert van Es , Stamatis Kolios

Clustered standard errors and approximate randomization tests are popular inference methods that allow for dependence within observations. However, they require researchers to know the cluster structure ex ante. We propose a procedure to…

Econometrics · Economics 2022-01-14 Yong Cai

Strict frequentism defines probability as the limiting relative frequency in an infinite sequence. What if the limit does not exist? We present a broader theory, which is applicable also to random phenomena that exhibit diverging relative…

Statistics Theory · Mathematics 2023-06-07 Christian Fröhlich , Rabanus Derr , Robert C. Williamson

Quantifying the similarity between two mathematical structures or datasets constitutes a particularly interesting and useful operation in several theoretical and applied problems. Aimed at this specific objective, the Jaccard index has been…

Machine Learning · Computer Science 2021-11-19 Luciano da F. Costa

Based on the competition between members of a hierarchy of length scales in complex multi-scale systems, it is shown how clustering of active quantities into concentrated sets, like bubbles in a Swiss cheese, is a generic property that…

Fluid Dynamics · Physics 2009-11-11 J. D. Gibbon , E. S. Titi

The random-cluster model, a correlated bond percolation model, unifies a range of important models of statistical mechanics in one description, including independent bond percolation, the Potts model and uniform spanning trees. By…

Statistical Mechanics · Physics 2016-01-28 Eren Metin Elçi , Martin Weigel , Nikolaos G. Fytas

Data clustering is the process of identifying natural groupings or clusters within multidimensional data based on some similarity measure. Clustering is a fundamental process in many different disciplines. Hence, researchers from different…

Machine Learning · Computer Science 2014-08-26 Sibei Yang , Liangde Tao , Bingchen Gong

Stars form predominantly in groups usually denoted as clusters or associations. The observed stellar groups display a broad spectrum of masses, sizes and other properties, so it is often assumed that there is no underlying structure in this…

Solar and Stellar Astrophysics · Physics 2016-02-03 S. Pfalzner , H. Kirk , A. Sills , J. S. Urquhart , J. Kauffmann , M. A. Kuhn , A. Bhandare , K. M. Menten

One property of networks that has received comparatively little attention is hierarchy, i.e., the property of having vertices that cluster together in groups, which then join to form groups of groups, and so forth, up through all levels of…

Physics and Society · Physics 2008-04-12 Aaron Clauset , Cristopher Moore , M. E. J. Newman

Clustering algorithms partition a dataset into groups of similar points. The primary contribution of this article is the Multiscale Spatially-Regularized Diffusion Learning (M-SRDL) clustering algorithm, which uses spatially-regularized…

Machine Learning · Computer Science 2022-04-08 Sam L. Polk , James M. Murphy