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In this paper we define the magnitude of metric spaces using measures rather than finite subsets as had been done previously and show that this agrees with earlier work with Leinster in arXiv:0908.1582. An explicit formula for the magnitude…

Differential Geometry · Mathematics 2013-02-14 Simon Willerton

Recent work of Fili and the author examines an ultrametric version of the Mahler measure, denoted $M_\infty(\alpha)$ for an algebraic number $\alpha$. We show that the computation of $M_\infty(\alpha)$ can be reduced to a certain search…

Number Theory · Mathematics 2025-04-02 Charles L. Samuels

The magnitude of metric spaces does not appear to possess a simple, convenient continuity property, and previous studies have presented affirmative results under additional constraints or weaker notions, as well as counterexamples. In this…

Metric Geometry · Mathematics 2026-01-30 Byungchang So

The magnitude of a graph can be thought of as an integer power series associated to a graph; Leinster introduced it using his idea of magnitude of a metric space. Here we introduce a bigraded homology theory for graphs which has the…

Combinatorics · Mathematics 2020-07-13 Richard Hepworth , Simon Willerton

The magnitude homology, introduced by R. Hepworth and S. Willerton, offers a topological invariant that enables the study of graph properties. Hypergraphs, being a generalization of graphs, serve as popular mathematical models for data with…

Algebraic Topology · Mathematics 2024-12-24 Wanying Bi , Jingyan Li , Jie Wu

We present several applications of matrix-theoretic inequalities to the magnitude of metric spaces. We first resolve an open problem by showing that the magnitude of any finite metric space of negative type is less than or equal to its…

Metric Geometry · Mathematics 2025-09-30 Kiyonori Gomi , Mark Meckes

The metric complexity (sometimes called Leinster--Cobbold maximum diversity) of a compact metric space is a recently introduced isometry-invariant of compact metric spaces which generalizes the notion of cardinality, and can be thought of…

Metric Geometry · Mathematics 2026-03-24 Gautam Aishwarya , Dongbin Li , Mokshay Madiman , Mark Meckes

In ancient Greek mathematics, magnitudes such as lengths were strictly distinguished from numbers. In modern quantity calculus, a distinction is made between quantities and scalars that serve as measures of quantities. It can be argued that…

Rings and Algebras · Mathematics 2023-01-12 Dan Jonsson

A new homological dimension is introduced to measure the quality of resolutions of `singular' finite dimensional algebras (of infinite global dimension) by `regular' ones (of finite global dimension). Upper bounds are established in terms…

Representation Theory · Mathematics 2017-06-27 Hongxing Chen , Ming Fang , Otto Kerner , Steffen Koenig , Kunio Yamagata

Magnitude homology is an $\mathbf{R}^+$-graded homology theory of metric spaces that captures information on the complexity of geodesics. Here we address the question: when are two metric spaces magnitude homology equivalent, in the sense…

Metric Geometry · Mathematics 2026-02-25 Adrián Doña Mateo , Tom Leinster

Metric space magnitude, an active subject of research in algebraic topology, originally arose in the context of biology, where it was used to represent the effective number of distinct species in an environment. In a more general setting,…

Machine Learning · Computer Science 2020-07-06 Eric Bunch , Daniel Dickinson , Jeffery Kline , Glenn Fung

Magnitude is an invariant of metric spaces with origins in category theory. Using potential theoretic methods, Barcel\'o and Carbery gave an algorithm for calculating the magnitude of any odd dimensional ball in Euclidean space, and they…

Metric Geometry · Mathematics 2020-05-12 Simon Willerton

In this paper, a class of holomorphic invariant metrics is introduced on the irreducible classical domains of type I-IV, which are strongly pseudoconvex complex Finsler metrics in the strict sense of M. Abate and G. Patrizio[2]. These…

Differential Geometry · Mathematics 2023-04-11 Xiaoshu Ge , Chunping Zhong

Hepworth, Willerton, Leinster and Shulman introduced the magnitude homology groups for enriched categories, in particular, for metric spaces. The purpose of this paper is to describe the magnitude homology group of a metric space in terms…

Algebraic Topology · Mathematics 2021-09-03 Ryuki Kaneta , Masahiko Yoshinaga

Magnitude and (co)weightings are quite general constructions in enriched categories, yet they have been developed almost exclusively in the context of Lawvere metric spaces. We construct a meaningful notion of magnitude for flow graphs…

Category Theory · Mathematics 2023-08-03 Steve Huntsman

A finitely-additive measure $\lambda $ on an infinite-dimensional real Hilbert space $E$ which is invariant with respect to shifts and orthogonal mappings has been defined. This measure can be considered as the analog of the Lebesgue…

Functional Analysis · Mathematics 2021-09-28 Vsevolod Sakbaev

A nonnegative number d_infinity, called asymptotic dimension, is associated with any metric space. Such number detects the asymptotic properties of the space (being zero on bounded metric spaces), fulfills the properties of a dimension, and…

Differential Geometry · Mathematics 2007-05-23 Daniele Guido , Tommaso Isola

This paper studies the magnitude homology of graphs focusing mainly on the relationship between its diagonality and the girth. Magnitude and magnitude homology are formulations of the Euler characteristic and the corresponding homology,…

Algebraic Topology · Mathematics 2021-02-10 Yasuhiko Asao , Yasuaki Hiraoka , Shu Kanazawa

The Alpha Group is an abstract geometry group in $\mathbb{R}^4$. The way it was conceived allows a new interpretation of the structure of hypercomplex space, with a new geometry and spatial topology, and a meaning for the geometric…

Differential Geometry · Mathematics 2025-07-29 Cleber Souza Correa , Thiago Braido Nogueira de Melo , Diogo Machado Custódio

Motivated by Leinster-Cobbold measures of biodiversity, the notion of the spread of a finite metric space is introduced. This is related to Leinster's magnitude of a metric space. Spread is generalized to infinite metric spaces equipped…

Metric Geometry · Mathematics 2015-01-07 Simon Willerton