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We establish a sharp edge-connectivity estimate for graphs with non-negative Bakry-\'Emery curvature. This leads to a geometric criterion for the existence of a perfect matching. Precisely, we show that any regular graph with non-negative…

Combinatorics · Mathematics 2025-07-25 Kaizhe Chen , Jack H. Koolen , Shiping Liu

We prove diameter bounds for graphs having positive Ricci-curvature bound in Bakry-Emery sense. One result using only curvature and maximal vertex degree is sharp in case of hypercubes. The other result depends on an additional dimension…

Differential Geometry · Mathematics 2019-04-03 Shiping Liu , Florentin Münch , Norbert Peyerimhoff

In this sequence of two papers, we introduce a curvature flow on (mixed) weighted graphs which is based on the Bakry-\'Emery calculus. The flow is described via a time-continuous evolution through the weighting schemes. By adapting this…

Classical Analysis and ODEs · Mathematics 2022-12-27 David Cushing , Supanat Kamtue , Shiping Liu , Florentin Münch , Norbert Peyerimhoff , Hugo Benedict Snodgrass

In this article, we prove gradient estimates under Bakry-Emery curvature bounds for unbounded graph Laplacians which satisfy an ellipticity assumption. As applications, we study completeness and finiteness of stochastically complete graphs…

Differential Geometry · Mathematics 2020-11-24 Matthias Keller , Florentin Münch

In this second part of a sequence of two papers, we discuss the implementation of a curvature flow on weighted graphs based on the Bakry-\'Emery calculus. This flow can be adapted to preserve the Markovian property and its limits as time…

Classical Analysis and ODEs · Mathematics 2022-12-26 David Cushing , Supanat Kamtue , Shiping Liu , Florentin Münch , Norbert Peyerimhoff , Ben Snodgrass

We classify all cubic graphs with either non-negative Ollivier-Ricci curvature or non-negative Bakry-\'Emery curvature everywhere. We show in both curvature notions that the non-negatively curved graphs are the prism graphs and the M\"obius…

Combinatorics · Mathematics 2023-10-26 David Cushing , Riikka Kangaslampi , Valtteri Lipiäinen , Shiping Liu , George William Stagg

We investigate whether there is a relationship between the discrete Bakry-\'{E}mery curvature of a graph and the smooth curvature of an ambient surface into which the graph is embedded geodesically. As we used weighted graphs as test…

Combinatorics · Mathematics 2023-11-10 Gökçe Çakmak , Ali Deniz , Şahin Koçak , Murat Limoncu

We introduce the notion of Bonnet-Myers and Lichnerowicz sharpness in the Ollivier Ricci curvature sense. Our main result is a classification of all self-centered Bonnet-Myers sharp graphs (hypercubes, cocktail party graphs,…

Combinatorics · Mathematics 2018-07-09 David Cushing , Supanat Kamtue , Jack Koolen , Shiping Liu , Florentin Münch , Norbert Peyerimhoff

We study the Bakry-\'Emery curvature function $\mathcal{K}_{G,x}:(0,\infty]\to \mathbb{R}$ of a vertex $x$ in a locally finite graph $G$ systematically. Here $\mathcal{K}_{G,x}(\mathcal{N})$ is defined as the optimal curvature lower bound…

Combinatorics · Mathematics 2019-04-03 David Cushing , Shiping Liu , Norbert Peyerimhoff

We prove distance bounds for graphs possessing positive Bakry-\'Emery curvature apart from an exceptional set, where the curvature is allowed to be non-positive. If the set of non-positively curved vertices is finite, then the graph admits…

Differential Geometry · Mathematics 2019-03-26 Shiping Liu , Florentin Münch , Norbert Peyerimhoff , Christian Rose

The definition of Ricci curvature on graphs in Bakry-\'Emery's sense based on curvature dimension condition was introduced by Lin and Yau [\emph{Math. Res. Lett.}, 2010]. Hua and Lin [\emph{Comm. Anal. Geom.}, 2019] classified unweighted…

Combinatorics · Mathematics 2024-08-20 Huiqiu Lin , Zhe You

In this paper, we reformulate the Bakry-\'Emery curvature on a weighted graph in terms of the smallest eigenvalue of a rank one perturbation of the so-called curvature matrix using Schur complement. This new viewpoint allows us to show…

Combinatorics · Mathematics 2022-01-26 David Cushing , Supanat Kamtue , Shiping Liu , Norbert Peyerimhoff

Liu, M\"unch, and Peyerimhoff introduced the notion of Bakry-\'Emery curvature for connection graphs as a means to derive Buser-type bounds on the eigenvalues of connection Laplacians. In this work, we present a reformulation of the…

Combinatorics · Mathematics 2026-04-08 Chunyang Hu , Shiping Liu

In this paper, we compare Ollivier Ricci curvature and Bakry-\'Emery curvature notions on combinatorial graphs and discuss connections to various types of Ricci flatness. We show that non-negativity of Ollivier Ricci curvature implies…

Combinatorics · Mathematics 2023-10-26 David Cushing , Supanat Kamtue , Riikka Kangaslampi , Shiping Liu , Norbert Peyerimhoff

We study graphs with nonnegative Bakry-\'Emery curvature or Ollivier curvature outside a finite subset. For such a graph, via introducing the discrete Gromov-Hausdorff convergence we prove that the space of bounded harmonic functions is…

Differential Geometry · Mathematics 2022-10-04 Bobo Hua , Florentin Münch

We characterise the form of all simple, finite graphs for which the girth of the graph is equal to the circumference of the graph. We apply this to prove a bound on the number of edges in such a graph.

Combinatorics · Mathematics 2022-10-11 Lewis Stanton , Jeffrey Thompson

In this article we prove that antitrees with suitable growth properties are examples of infinite graphs exhibiting strictly positive curvature in various contexts: in the normalized and non-normalized Bakry-\'Emery setting as well in the…

Combinatorics · Mathematics 2018-01-30 David Cushing , Shiping Liu , Florentin Münch , Norbert Peyerimhoff

In this paper we consider global $\theta$-curvatures of finite Markov chains with associated means $\theta$ in the spirit of the entropic curvature (based on the logarithmic mean) by Erbar-Maas and Mielke. As in the case of Bakry-\'Emery…

Differential Geometry · Mathematics 2025-04-01 Supanat Kamtue , Shiping Liu , Florentin Münch , Norbert Peyerimhoff

Due to their elegant and simple nature, unitary Cayley graphs have been an active research topic in the literature. These graphs are naturally connected to several branches of mathematics, including number theory, finite algebra,…

Combinatorics · Mathematics 2024-09-04 Ján Mináč , Tung T. Nguyen , Nguyen Duy Tân

Sharp estimates for mean curvature flow of graphs are shown and examples are given to illustrate why these are sharp. The estimates improves earlier (non-sharp) estimates of Klaus Ecker and Gerhard Huisken.

Analysis of PDEs · Mathematics 2007-05-23 Tobias H. Colding , W. P. Minicozzi
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