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Related papers: Sharp Davies-Gaffney-Grigor'yan Lemma on Graphs

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In this work, we develop a unified framework for establishing sharp threshold results for various Ramsey properties. To achieve this, we view such properties as non-colourability of auxiliary hypergraphs. Our main technical result gives…

Combinatorics · Mathematics 2026-03-04 Ehud Friedgut , Eden Kuperwasser , Wojciech Samotij , Mathias Schacht

On doubling metric measure spaces endowed with a strongly local regular Dirichlet form, we show some characterisations of pointwise upper bounds of the heat kernel in terms of global scale-invariant inequalities that correspond respectively…

Analysis of PDEs · Mathematics 2013-11-15 Salahaddine Boutayeb , Thierry Coulhon , Adam Sikora

The blow-up lemma states that a system of super-regular pairs contains all bounded degree spanning graphs as subgraphs that embed into a corresponding system of complete pairs. This lemma has far-reaching applications in extremal…

Combinatorics · Mathematics 2025-08-29 Peter Allen , Julia Böttcher , Hiep Hàn , Yoshiharu Kohayakawa , Yury Person

Let $G$ be a graph and $\Gamma$ a finite abelian group. The zero-sum Ramsey number of $G$ over $\Gamma$, denoted by $R(G, \Gamma)$, is the smallest positive integer $t$ (if it exists) such that any edge-colouring $c:E(K_t)\to\Gamma$…

Combinatorics · Mathematics 2026-05-11 Jasmin Katz , Xiaopan Lian , Alexandru Malekshahian , Andrey Shapiro

We consider a graphene sheet folded in an arbitrary geometry, compact or with nanotube-like open boundaries. In the continuous limit, the Hamiltonian takes the form of the Dirac operator, which provides a good description of the low energy…

Materials Science · Physics 2008-11-26 Jiannis K. Pachos , Michael Stone

The Havel-Hakimi algorithm iteratively reduces the degree sequence of a graph to a list of zeroes. As shown by Favaron, Mah\'eo, and Sacl\'e, the number of zeroes produced, known as the residue, is a lower bound on the independence number…

Combinatorics · Mathematics 2019-09-17 Michael D. Barrus , Grant Molnar

Many real-world networks can be modeled as graphs. Finding dense subgraphs is a key problem in graph mining with applications in diverse domains. In this paper, we consider two variants of the densest subgraph problem where multiple graph…

Data Structures and Algorithms · Computer Science 2025-02-04 Chamalee Wickrama Arachchi , Nikolaj Tatti

We obtain pointwise lower bounds for heat kernels of higher order differential operators with Dirichlet boundary conditions on bounded domains in $\R^N$. The bounds exhibit explicitly the nature of the spatial decay of the heat kernel close…

Spectral Theory · Mathematics 2011-10-18 Narinder S Claire

Szemer\'edi's Regularity Lemma is an important tool for analyzing the structure of dense graphs. There are versions of the Regularity Lemma for sparse graphs, but these only apply when the graph satisfies some local density condition. In…

Combinatorics · Mathematics 2010-11-09 Alexander Scott

Kernels on graphs have had limited options for node-level problems. To address this, we present a novel, generalized kernel for graphs with node feature data for semi-supervised learning. The kernel is derived from a regularization…

Machine Learning · Computer Science 2022-11-29 Yin-Cong Zhi , Felix L. Opolka , Yin Cheng Ng , Pietro Liò , Xiaowen Dong

This note contains a new combinatorial proof of Cramer's rule based on the Gessel-Viennot-Lindstrom Lemma.

Combinatorics · Mathematics 2025-09-08 Sudip Bera

We introduce the Density Formula for (topological) drawings of graphs in the plane or on the sphere, which relates the number of edges, vertices, crossings, and sizes of cells in the drawing. We demonstrate its capability by providing…

The celebrated Hajnal-Szemer\'edi theorem gives the precise minimum degree threshold that forces a graph to contain a perfect K_k-packing. Fischer's conjecture states that the analogous result holds for all multipartite graphs except for…

Combinatorics · Mathematics 2015-09-15 Peter Keevash , Richard Mycroft

In this paper, we obtain an explicit formula for the heat kernel on the infinite Cayley graph of the modular group $\operatorname{PSL}_2\mathbb{Z}$, given by the presentation $\langle a,b\mid a^2=1, b^3=1\rangle$. Our approach extends the…

Group Theory · Mathematics 2025-07-01 Anders Karlsson , Kamila Kashaeva

The maximum entropy principle is applied to the formal derivation of isothermal, Euler-like equations for semiclassical fermions (electrons and holes) in graphene. After proving general mathematical properties of the equations so obtained,…

Mathematical Physics · Physics 2015-06-18 Luigi Barletti

We consider graphs associated to Delone sets in Euclidean space. Such graphs arise in various ways from tilings. Here, we provide a unified framework. In this context, we study the associated Laplace operators and show Gaussian heat kernel…

Spectral Theory · Mathematics 2017-04-26 Sebastian Haeseler , Xueping Huang , Daniel Lenz , Felix Pogorzelski

We obtain two-sided heat kernel estimates for Riemannian manifolds with ends with mixed boundary condition, provided that the heat kernels for the ends are well understood. These results extend previous results of Grigor'yan and…

Differential Geometry · Mathematics 2025-01-15 Emily Dautenhahn , Laurent Saloff-Coste

We work with simple graphs in ZF (Zermelo--Fraenkel set theory without the Axiom of Choice (AC)) and assume that the sets of colors can be either well-orderable or non-well-orderable to prove that the following statements are equivalent to…

Combinatorics · Mathematics 2025-07-23 Amitayu Banerjee , Zalán Molnár , Alexa Gopaulsingh

In this paper we introduce the notion of $\Sigma$-colouring of a graph $G$: For given subsets $\Sigma(v)$ of neighbours of $v$, for every $v\in V(G)$, this is a proper colouring of the vertices of $G$ such that, in addition, vertices that…

Combinatorics · Mathematics 2015-09-28 Omid Amini , Louis Esperet , Jan van den Heuvel

We consider the monomer-dimer model on weighted graphs embedded in surfaces with boundary, with the restriction that only monomers located on the boundary are allowed. We give a Pfaffian formula for the corresponding partition function,…

Mathematical Physics · Physics 2018-04-04 Anh Minh Pham
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