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Galaxy populations show bimodality in a variety of properties: stellar mass, colour, specific star-formation rate, size, and S\'ersic index. These parameters are our feature space. We use an existing sample of 7556 galaxies from the Galaxy…

A Parallel Self-Organizing Map (Parallel-SOM) is proposed to modify Kohonen's SOM in parallel computing environment. In this model, two separate layers of neurons are connected together. The number of neurons in both layers and connections…

Quantum Physics · Physics 2007-05-23 Li Weigang

One of the main objectives of stage IV galaxy surveys is to constrain gravity on cosmological scales. To this end, it is crucial to make accurate theoretical predictions in the nonlinear regime of structure formation in order to maximise…

Cosmology and Nongalactic Astrophysics · Physics 2023-03-14 Bartolomeo Fiorini

This paper introduces the concept of a bi-scale metric for use in the cooperative phase of the self-organizing map (SOM) algorithm. Use of a bi-scale metric allows segmentation of the map into a number of regions, corresponding to…

Neural and Evolutionary Computing · Computer Science 2018-05-10 William H. Wilson

Astrophysical tests of modified modified gravity theories in the nearby universe have been emphasized recently by Hui, Nicolis and Stubbs (2009) and Jain and VanderPlas (2011). A key element of such tests is the screening mechanism whereby…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-04 Anna Cabré , Vinu Vikram , Gong-Bo Zhao , Bhuvnesh Jain , Kazuya Koyama

The self-organizing map (SOM) is an unsupervised artificial neural network that is widely used in, e.g., data mining and visualization. Supervised and semi-supervised learning methods have been proposed for the SOM. However, their teacher…

Neural and Evolutionary Computing · Computer Science 2020-03-03 Akinari Onishi

Self-Organizing Maps (SOMs) provide topology-preserving projections of high-dimensional data, yet their use as generative models remains largely unexplored. We show that the activation pattern of a SOM -- the squared distances to its…

Machine Learning · Computer Science 2026-02-24 Alessandro Londei , Matteo Benati , Denise Lanzieri , Vittorio Loreto

We analyze cosmography as a tool to constrain modified gravity theories. We take four distinct models and obtain their parameters in terms of the cosmographic parameters favored by observational data of strong gravitational lensing. We…

General Relativity and Quantum Cosmology · Physics 2025-02-06 Mario H. Amante , Andrés Lizardo , Javier Chagoya , C. Ortiz

Chameleon, environmentally dependent dilaton, and symmetron gravity are three models of modified gravity in which the effects of the additional scalar degree of freedom are screened in dense environments. They have been extensively studied…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-18 Anne-Christine Davis , Ruth Gregory , Rahul Jha , Jessica Muir

This paper defines a new learning architecture, Layered Self-Organizing Maps (LSOMs), that uses the SOM and supervised-SOM learning algorithms. The architecture is validated with the MNIST database of hand-written digit images. LSOMs are…

Computer Vision and Pattern Recognition · Computer Science 2018-03-29 David Friedlander

Texture is one of the most important properties of visual surface that helps in discriminating one object from another or an object from background. The self-organizing map (SOM) is an excellent tool in exploratory phase of data mining. It…

Computer Vision and Pattern Recognition · Computer Science 2014-08-20 Marghny H. Mohamed , Mohammed M. Abdelsamea

Self-organising maps are a powerful tool for cluster analysis in a wide range of data contexts. From the pioneer work of Kohonen, many variants and improvements have been proposed. This review focuses on the last decade, in order to provide…

Neural and Evolutionary Computing · Computer Science 2025-01-16 Axel Guérin , Pierre Chauvet , Frédéric Saubion

We study environment-dependent clustering using the marked correlation function applied to Hu-Sawicki $f(R)$ modified gravity simulations. This gravity theory enriches the structure formation by enhancing gravity in a scale-dependent form.…

Cosmology and Nongalactic Astrophysics · Physics 2026-01-12 Joaquin Armijo , Lucas Da Costa

We study the linear and nonlinear structure formation in the dilaton and symmetron models of modified gravity using a generic parameterisation which describes a large class of scenarios using only a few parameters, such as the coupling…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-05 Philippe Brax , Anne-Christine Davis , Baojiu Li , Hans A. Winther , Gong-Bo Zhao

Deep learning based localization and mapping has recently attracted significant attention. Instead of creating hand-designed algorithms through exploitation of physical models or geometric theories, deep learning based solutions provide an…

Computer Vision and Pattern Recognition · Computer Science 2020-07-01 Changhao Chen , Bing Wang , Chris Xiaoxuan Lu , Niki Trigoni , Andrew Markham

We present measurements of the spatial clustering statistics in redshift space of various scalar field modified gravity simulations. We utilise the two-point and the three-point correlation functions to quantify the spatial distribution of…

Cosmology and Nongalactic Astrophysics · Physics 2016-07-20 Cristiano G. Sabiu , David F. Mota , Claudio Llinares , Changbom Park

This is a brief review of modified gravity cosmologies. Generically extensions of gravity action involve higher derivative terms, which can result in ghosts and instabilities. There are three ways to circumvent this: Chern-Simons terms,…

General Relativity and Quantum Cosmology · Physics 2010-02-24 Tomi S. Koivisto

We investigate the potential of weak gravitational lensing maps to differentiate between distinct cosmological models, considering cosmic variance due to a limited map extension and the presence of noise. We introduce a measure of the…

Astrophysics · Physics 2009-11-07 Antonio Guimarães

This work describes the implementation and application of a correlation determination method based on Self Organizing Maps and Bayesian Inference (SOMBI). SOMBI aims to automatically identify relations between different observed parameters…

Cosmology and Nongalactic Astrophysics · Physics 2016-11-02 Philipp Frank , Jens Jasche , Torsten A. Enßlin

We consider modified gravity models driven by a scalar field whose effects are screened in high density regions due to the presence of non-linearities in its interaction potential and/or its coupling to matter. Our approach covers…

Cosmology and Nongalactic Astrophysics · Physics 2013-05-30 Philippe Brax , Anne-Christine Davis , Baojiu Li , Hans A. Winther