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We explore properties of generalized Paley graphs and we extend a result of Lim and Praeger by providing a more precise description of the connected components of disconnected generalized Paley graphs. This result leads to a new…

Combinatorics · Mathematics 2024-09-13 Vincent Bonini , Daniel Chamberlin , Stephen Cook , Parthiv Seetharaman , Tri Tran

Graph Ricci curvature is crucial as it geometrically quantifies network structure. It pinpoints bottlenecks via negative curvature, identifies cohesive communities with positive curvature, and highlights robust hubs. This guides network…

Analysis of PDEs · Mathematics 2026-04-03 Juan Zhao , Jicheng Ma , Yunyan Yang , Liang Zhao

A goal in network science is the geometrical characterization of complex networks. In this direction, we (arXiv:1603.00386; J. Stat. Mech. (2016) P063206) have recently introduced the Forman's discretization of Ricci curvature to the realm…

Molecular Networks · Quantitative Biology 2017-02-28 R. P. Sreejith , Jürgen Jost , Emil Saucan , Areejit Samal

Gurski and Wanke showed that a graph class C has bounded tree-width if and only if its associated class of directed line graphs has bounded clique-width. Inevitably -- asking whether this relationship lifts to directed graphs -- we…

Combinatorics · Mathematics 2025-02-24 Benjamin Merlin Bumpus , Kitty Meeks , William Pettersson

By Hall's marriage theorem, we study lower bounds of the Lin-Lu-Yau curvature of amply regular graphs with girth $3$ or $4$ under different parameter restrictions. As a consequence, we show that each conference graph has positive Lin-Lu-Yau…

Combinatorics · Mathematics 2022-01-26 Xintian Li , Shiping Liu

We introduce a new arc in directed graphs of integers. Among other things, we determine the positive integers that have arcs to all except a finite number of positive integers. We also propose some possible research problems at the end of…

Number Theory · Mathematics 2023-03-24 Phakhinkon Napp Phunphayap , Passawan Noppakaew , Prapanpong Pongsriiam

We establish an inequality among the Ricci curvature, the squared mean curvature, and the normal curvature for real hypersurfaces in complex space forms. We classify real hypersurfaces in two-dimensional non-flat complex space forms which…

Differential Geometry · Mathematics 2018-05-25 Toru Sasahara

Motivated by the search for geometric observables in nonperturbative quantum gravity, we define a notion of coarse-grained Ricci curvature. It is based on a particular way of extracting the local Ricci curvature of a smooth Riemannian…

High Energy Physics - Theory · Physics 2018-02-21 N. Klitgaard , R. Loll

This is a survey paper. We study the Ricci curvature and spectrum of graphs, as well as the exterior forms and deRahm cohomology on graphs.

Combinatorics · Mathematics 2012-04-17 Yong Lin , Shing-Tung Yau

In this paper, we define the curvature dimension inequalities CD(m, K) on finite directed graphs modifying the case of undirected graphs. As a main result, we evaluate m and K on finite directed graphs.

Differential Geometry · Mathematics 2017-01-09 Taiki Yamada

In this paper, we study the evolution of metrics on finite trees under continuous-time Ricci flows based on the Lin-Lu-Yau version of Ollivier Ricci curvature. We analyze long-time dynamics of edge weights and curvatures, providing precise…

Differential Geometry · Mathematics 2026-01-29 Shuliang Bai , Bobo Hua , Yong Lin , Shuang Liu

This erratum will correct the classification of Theorem 1 in Lin-Lu-Yau, Comm. Anal. Geom., 2014, that misses the Triplex graph.

Combinatorics · Mathematics 2019-05-09 David Cushing , Riikka Kangaslampi , Yong Lin , Shiping Liu , Linyuan Lu , Shing-Tung Yau

Given a planar graph derived from a spherical, euclidean or hyperbolic tessellation, one can define a discrete curvature by combinatorial properties, which after embedding the graph in a compact 2d-manifold, becomes the Gaussian curvature.

General Relativity and Quantum Cosmology · Physics 2007-05-23 M. Lorente

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 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

We introduce a notion of doubly warped product of weighted graphs that is consistent with the doubly warped product in the Riemannian setting. We establish various discrete Bakry-\'Emery Ricci curvature-dimension bounds for such warped…

Differential Geometry · Mathematics 2021-10-26 Zohreh Fathi , Sajjad Lakzian

The first non-zero Laplacian eigenvalue $\lambda_1$ of a finite graph is bounded below by its minimum Lin--Lu--Yau curvature $\kappa$. This is a discrete analogue of the classical Lichnerowicz Theorem. A graph with $\lambda_1=\kappa$ is…

Combinatorics · Mathematics 2026-02-12 Kaizhe Chen , Shiping Liu , Heng Zhang

A directed graph is set-homogeneous if, whenever U and V are isomorphic finite subdigraphs, there is an automorphism g of the digraph with U^g=V. Here, extending work of Lachlan on finite homogeneous digraphs, we classify finite…

Combinatorics · Mathematics 2010-11-19 Robert Gray , Dugald Macpherson , Cheryl E. Praeger , Gordon F. Royle

Characterizing shapes of high-dimensional objects via Ricci curvatures plays a critical role in many research areas in mathematics and physics. However, even though several discretizations of Ricci curvatures for discrete combinatorial…

Data Structures and Algorithms · Computer Science 2023-08-14 Bhaskar DasGupta , Elena Grigorescu , Tamalika Mukherjee

In this paper, we use the theory of Riordan matrices to introduce the notion of an oriented Riordan graph. The oriented Riordan graphs are a far-reaching generalization of the well known and well studied Toeplitz oriented graphs and…

Combinatorics · Mathematics 2020-09-04 Ji-Hwan Jung
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