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An answer to the question investigated in this paper brings a new characterization of internal groupoids such that: (a) it holds even when finite limits are not assumed to exist; (b) it is a full subcategory of the category of…

Category Theory · Mathematics 2022-11-24 Nelson Martins-Ferreira

We study the synchronous and asynchronous automatic structures on the fundamental group of a graph of groups in which each edge group is finite. Up to a natural equivalence relation, the set of biautomatic structures on such a graph product…

Group Theory · Mathematics 2008-02-03 Walter D. Neumann , Michael Shapiro

We examine which of the compact connected Lie groups that act transitively on spheres of different dimensions leave the unique spin structure of the sphere invariant. We study the notion of invariance of a spin structure and prove this…

Differential Geometry · Mathematics 2022-05-17 Jordi Daura Serrano , Michael Kohn , Marie-Amélie Lawn

In this series, we introduce and investigate the concept of connectoids, which captures the connectivity structure of various discrete objects such as undirected graphs, directed graphs, bidirected graphs, hypergraphs and finitary matroids.…

Combinatorics · Mathematics 2026-05-21 Nathan Bowler , Florian Reich

Graph embeddings have become a key and widely used technique within the field of graph mining, proving to be successful across a broad range of domains including social, citation, transportation and biological. Graph embedding techniques…

Machine Learning · Computer Science 2018-06-21 Stephen Bonner , Ibad Kureshi , John Brennan , Georgios Theodoropoulos , Andrew Stephen McGough , Boguslaw Obara

Given a system $\mathcal{G} =\{G_1,G_2,\dots,G_m\}$ of graphs/digraphs/hypergraphs on the common vertex set $V$ of size $n$, an $m$-edge graph/digraph/hypergraph $H$ on $V$ is transversal in $\mathcal{G}$ if there exists a bijection…

Combinatorics · Mathematics 2026-04-15 Wanting Sun , Guanghui Wang , Lan Wei

An invariant random subgroup of the countable group {\Gamma} is a random subgroup of {\Gamma} whose distribution is invariant under conjugation by all elements of {\Gamma}. We prove that for a nonamenable invariant random subgroup H, the…

Group Theory · Mathematics 2015-01-14 Miklos Abert , Yair Glasner , Balint Virag

Graphs are ubiquitous, and learning on graphs has become a cornerstone in artificial intelligence and data mining communities. Unlike pixel grids in images or sequential structures in language, graphs exhibit a typical non-Euclidean…

Machine Learning · Computer Science 2026-02-12 Li Sun , Qiqi Wan , Suyang Zhou , Zhenhao Huang , Philip S. Yu

In this paper we briefly survey the classical problem of understanding which Lie algebras admit a complex structure, put in the broader perspective of almost complex structures with special properties. We focus on the different behavior of…

Differential Geometry · Mathematics 2025-11-14 Lorenzo Sillari , Adriano Tomassini

Schanuel has pointed out that there are mathematically interesting categories whose relationship to the ring of integers is analogous to the relationship between the category of finite sets and the semi-ring of non-negative integers. Such…

Combinatorics · Mathematics 2007-05-23 James Propp

We develop a general diagrammatic theory of welded graphs, and provide an extension of Satoh's Tube map from welded graphs to ribbon surface-links. As a topological application, we obtain a complete link-homotopy classification of so-called…

Geometric Topology · Mathematics 2025-07-29 Benjamin Audoux , Jean-Baptiste Meilhan , Akira Yasuhara

In this paper we consider the generalized anchored configuration spaces on $n$ labeled points on a~graph. These are the spaces of all configurations of $n$ points on a~fixed graph $G$, subject to the condition that at least $q$ vertices in…

Algebraic Topology · Mathematics 2024-01-22 Dmitry N. Kozlov

In this article we give an algorithm for determining the generators and relations for the rings of semi-invariant functions on irreducible components of representation spaces for gentle string algebras. These rings of semi-invariants turn…

Representation Theory · Mathematics 2011-06-07 Andrew T. Carroll , Jerzy Weyman

The paper deals with the cohomological invariants of smooth and connected linear algebraic groups over an arbitrary field. More precisely, we study degree $2$ invariants with coefficients $\mathbb{Q}/\mathbb{Z}(1)$, that is invariants…

Algebraic Geometry · Mathematics 2025-09-30 Alexandre Lourdeaux

For many graph-related problems, it can be essential to have a set of structurally diverse graphs. For instance, such graphs can be used for testing graph algorithms or their neural approximations. However, to the best of our knowledge, the…

Machine Learning · Computer Science 2024-12-13 Fedor Velikonivtsev , Mikhail Mironov , Liudmila Prokhorenkova

We develop a formalism to address statistical pattern recognition of graph valued data. Of particular interest is the case of all graphs having the same number of uniquely labeled vertices. When the vertex labels are latent, such graphs are…

Quantitative Methods · Quantitative Biology 2012-10-17 Joshua T. Vogelstein , Carey E. Priebe

Intriguing issues in one-dimensional non-reciprocal topological systems include the breakdown of usual bulk-edge correspondence and the occurrence of half-integer topological invariants. In order to understand these unusual topological…

Mesoscale and Nanoscale Physics · Physics 2020-07-22 Hui Jiang , Rong Lü , Shu Chen

We study the geometry of Lie groups $G$ with a continuous Finsler metric, assuming the existence of a subgroup $K$ such that the metric is right-invariant for the action of $K$. We present a systematic study of the metric and geodesic…

Differential Geometry · Mathematics 2019-05-13 Gabriel Larotonda

We describe two locally finite graphs naturally associated to each knot type K, called Reidemeister graphs. We determine several local and global properties of these graphs and prove that in one case the graph-isomorphism type is a complete…

Geometric Topology · Mathematics 2020-04-29 Agnese Barbensi , Daniele Celoria

Statistical inference for exponential-family models of random graphs with dependent edges is challenging. We stress the importance of additional structure and show that additional structure facilitates statistical inference. A simple…

Statistics Theory · Mathematics 2020-03-13 Michael Schweinberger , Jonathan Stewart