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We give inequalities relating the eigenvalues of the adjacency matrix and the Laplacian of a graph, and its minimum and maximum degrees. The results are applied to derive new conditions for quasi-randomness of graphs.

Combinatorics · Mathematics 2007-05-23 Vladimir Nikiforov

The O(d) Synchronization problem consists of estimating a set of unknown orthogonal transformations O_i from noisy measurements of a subset of the pairwise ratios O_iO_j^{-1}. We formulate and prove a Cheeger-type inequality that relates a…

Spectral Theory · Mathematics 2013-09-23 Afonso S. Bandeira , Amit Singer , Daniel A. Spielman

In this paper we deduce a formula for the fractional Laplace operator $(-\Delta)^{s}$ on radially symmetric functions useful for some applications. We give a criterion of subharmonicity associated with $(-\Delta)^{s}$, and apply it to a…

Analysis of PDEs · Mathematics 2012-03-15 Fausto Ferrari , Igor E. Verbitsky

An isoperimetric constant relating length and stable area, or alternatively for hyperbolic manifolds, length and stable commutator length, serves as a Cheeger constant for the smallest eigenvalue of the Hodge Laplacian acting on coexact…

Geometric Topology · Mathematics 2026-05-06 Cameron Gates Rudd

Cheeger's fundamental inequality states that any edge-weighted graph has a vertex subset $S$ such that its expansion (a.k.a. conductance) is bounded as follows: \[ \phi(S) \defeq \frac{w(S,\bar{S})}{\min \set{w(S), w(\bar{S})}} \leq…

Data Structures and Algorithms · Computer Science 2015-03-19 Anand Louis , Prasad Raghavendra , Prasad Tetali , Santosh Vempala

Let $\tau(G)$ and $\kappa'(G)$ denote the edge-connectivity and the spanning tree packing number of a graph $G$, respectively. Proving a conjecture initiated by Cioaba and Wong, Liu et al. in 2014 showed that for any simple graph $G$ with…

Combinatorics · Mathematics 2018-08-21 Ruifang Liu , Hong-Jian Lai , Yingzhi Tian

We give a short and self-contained proof of the Boundary Harnack inequality for a class of domains satisfying some geometric conditions given in terms of a state function that behaves as the distance function to the boundary, is subharmonic…

Analysis of PDEs · Mathematics 2024-02-13 Francesco Paolo Maiale , Giorgio Tortone , Bozhidar Velichkov

We introduce a family of multi-way Cheeger-type constants $\{h_k^{\sigma}, k=1,2,\ldots, n\}$ on a signed graph $\Gamma=(G,\sigma)$ such that $h_k^{\sigma}=0$ if and only if $\Gamma$ has $k$ balanced connected components. These constants…

Combinatorics · Mathematics 2019-12-09 Fatihcan M. Atay , Shiping Liu

We prove that the optimal constant in the Lieb--Thirring inequality on a star graph with $N$ edges coincides with that on $\mathbb R$ if $N$ is even. For odd $N$ we show that this property holds when restricting to radial potentials and we…

Spectral Theory · Mathematics 2015-03-25 Semra Demirel-Frank

In this paper we prove the Hardy inequalities for the quadratic form of the Laplacian with the Landau Hamiltonian magnetic field. Moreover, we obtain Poincar\'e type inequality and inequalities with more general families of weights, all…

Functional Analysis · Mathematics 2017-05-02 Ari Laptev , Michael Ruzhansky , Nurgissa Yessirkegenov

We prove spectral localization for infinite metric graphs with a self-adjoint Laplace operator and a random potential. To do so we adapt the multiscale analysis (MSA) from the R^d-case to metric graphs. In the MSA a covering of the graph is…

Spectral Theory · Mathematics 2012-08-31 Carsten Schubert

We give an upper bound on the maximal eigenvalue of the adjacency matrix of a connected graph in terms of its maximum degree, diameter and order. This bound is best possible up to a constant factor and improves prevoius results of…

Combinatorics · Mathematics 2007-05-23 Vladimir Nikiforov

In this paper, we study the power of Gaussian curvature flow of a compact convex hypersurface and establish its Harnack inequality when the power is negative. In the Harnack inequality, we require that the absolute value of the power is…

Differential Geometry · Mathematics 2013-01-18 Yi Li

We investigate two related problems concerning the dimension of joint eigenspaces of the Laplace--Beltrami operator and a finite set of Hecke operators on $\mathbb{X}=\mathrm{PGL}_2(\mathbb{Z})\backslash \mathbb{H}$. First, we consider…

Number Theory · Mathematics 2025-02-25 Junehyuk Jung , Min Lee

In this paper we introduce a notion of magnetic field in the Heisenberg group and we study its influence on spectral properties of the corresponding magnetic (sub-elliptic) Laplacian. We show that uniform magnetic fields uplift the bottom…

Spectral Theory · Mathematics 2025-04-16 Biagio Cassano , Valentina Franceschi , David Krejcirik , Dario Prandi

We study the minimum number of distinct eigenvalues over a collection of matrices associated with a graph. Lower bounds are derived based on the existence or non-existence of certain cycle(s) in a graph. A key result proves that every…

Combinatorics · Mathematics 2024-11-22 Shaun Fallat , Himanshu Gupta , Allen Herman , Johnna Parenteau

We introduce a curvature-dimension condition for autonomous Lagrangians on weighted manifolds, which depends on the Euler-Lagrange dynamics on a single energy level. By generalizing Klartag's needle decomposition technique to the Lagrangian…

Differential Geometry · Mathematics 2026-02-11 Rotem Assouline

We prove a lower bound for the $k$-th Steklov eigenvalues in terms of an isoperimetric constant called the $k$-th Cheeger-Steklov constant in three different situations: finite spaces, measurable spaces, and Riemannian manifolds. These…

Spectral Theory · Mathematics 2017-12-11 Asma Hassannezhad , Laurent Miclo

Let $\Gamma$ be a compact metric graph, and denote by $\Delta$ the Laplace operator on $\Gamma$ with the first non-trivial eigenvalue $\lambda_1$. We prove the following Yang-Li-Yau type inequality on divisorial gonality $\gamma_{div}$ of…

Algebraic Geometry · Mathematics 2014-10-28 Omid Amini , Janne Kool

Many inequality relations between real vector quantities can be succinctly expressed as "weak (sub)majorization" relations. We explain these ideas and apply them in several areas: angles between subspaces, Ritz values, and graph Laplacian…

Numerical Analysis · Mathematics 2013-03-26 A. V. Knyazev , M. E. Argentati