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Eigenvalues inequalities involving (log) convex/concav functions and Hermitian matrices, positive unital maps are considered. Simple proofs of Bhatia-Kittaneh inequality and Naimark dilation theorem are given.

Operator Algebras · Mathematics 2007-05-23 Jaspal Singh Aujla Jean-Christophe Bourin

We strengthen and put in a broader perspective previous results of the first two authors on colliding permutations. The key to the present approach is a new non-asymptotic invariant for graphs.

Combinatorics · Mathematics 2007-09-28 János Körner , Claudia Malvenuto , Gábor Simonyi

The graph isomorphism problem is a main problem which has numerous applications in different fields. Thus, finding an efficient and easy to implement method to discriminate non-isomorphic graphs is valuable. In this paper, a new method is…

Combinatorics · Mathematics 2016-11-08 Ameneh Farhadian

We study the spectral properties of certain non-self-adjoint matrices associated with large directed graphs. Asymptotically the eigenvalues converge to certain curves, apart from a finite number that have limits not on these curves.

Spectral Theory · Mathematics 2008-02-12 E. B. Davies , Paul A. Incani

We study an elementary inequality supporting the classical Hermite-Hadamard inequality in the matrix setting. This leads to a number of interesting matrix inequalities such new Schatten p-norm estimates and new majorization

Functional Analysis · Mathematics 2022-01-05 Jean-Christophe Bourin , Eun-Young Lee

There is arbitrariness in optimum solutions of graph-theoretic problems that can give rise to unfairness. Incorporating fairness in such problems, however, can be done in multiple ways. For instance, fairness can be defined on an individual…

Optimization and Control · Mathematics 2023-11-28 Christopher Hojny , Frits Spieksma , Sten Wessel

We consider two recent conjectures of Harrington, Henninger-Voss, Karhadkar, Robinson and Wong concerning relationships between the sum index, difference index and exclusive sum number of graphs. One conjecture posits an exact relationship…

Combinatorics · Mathematics 2023-03-22 John Haslegrave

We develop the theory of linear evolution equations associated with the adjacency matrix of a graph, focusing in particular on infinite graphs of two kinds: uniformly locally finite graphs as well as locally finite line graphs. We discuss…

Dynamical Systems · Mathematics 2018-07-26 Delio Mugnolo

We apply eigenvalue interlacing techniques for obtaining lower and upper bounds for the sums of Laplacian eigenvalues of graphs, and characterize equality. This leads to generalizations of, and variations on theorems by Grone, and Grone and…

Spectral Theory · Mathematics 2013-11-20 A. Abiad , M. A. Fiol , W. H. Haemers , G. Perarnau

If $G$ is a graph, its Laplacian is the difference between diagonal matrix of its vertex degrees and its adjacency matrix. A one-edge connection of two graphs $G_{1}$ and $G_{2}$ is a graph $G=G_{1}\odot G_{2}$ with $V(G)=V(G_{1})\cup…

Combinatorics · Mathematics 2019-09-17 Doost Ali Mojdeh , Mohammad Habibi , Masoumeh Farkhondeh

In a very recent paper "\emph{On eigenvalues and equivalent transformation of trigonometric matrices}" (D. Zhang, Z. Lin, and Y. Liu, LAA 436, 71--78 (2012)), the authors motivated and discussed a trigonometric matrix that arises in the…

Numerical Analysis · Mathematics 2012-05-01 Suvrit Sra

Nikiforov\cite{nikiforov2017merging} introduced the concept of the $A_{\p}$-matrix as a convex linear combination of a graph's adjacency matrix and its diagonal matrix of vertex degrees. In this paper, we introduce a new variant of the…

Spectral Theory · Mathematics 2025-09-03 Piyush Sharma , Ravinder Kumar

We determine all graphs whose adjacency matrix has at most two eigenvalues (multiplicities included) different from $\pm 1$ and decide which of these graphs are determined by their spectrum. This includes the so-called friendship graphs,…

Combinatorics · Mathematics 2013-10-25 Sebastian M. Cioabă , Willem H. Haemers , Jason Vermette , Wiseley Wong

Let $ \Phi=(G, \varphi) $ be a connected complex unit gain graph ($ \mathbb{T} $-gain graph) on a simple graph $ G $ with $ n $ vertices and maximum vertex degree $ \Delta $. The associated adjacency matrix and degree matrix are denoted by…

Combinatorics · Mathematics 2021-01-12 Aniruddha Samanta , M. Rajesh Kannan

We present an adaptation of the Kato--Temple inequality for bounding perturbations of eigenvalues with applications to statistical inference for random graphs, specifically hypothesis testing and change-point detection. We obtain explicit…

Statistics Theory · Mathematics 2018-09-14 Joshua Cape , Minh Tang , Carey E. Priebe

In this paper we introduce a parameter $Mm(G)$, defined as the maximum over the minimal multiplicities of eigenvalues among all symmetric matrices corresponding to a graph $G$. We compute $Mm(G)$ for several families of graphs.

Spectral Theory · Mathematics 2016-06-17 Polona Oblak , Helena Šmigoc

Enlighted by the recent work of Hao Huang on sensitivity conjecture [arXiv:1907.00847], we propose a new definition of the dimension of graphs and establish a relationship between the chromatic number and the dimension.

Combinatorics · Mathematics 2021-10-01 X. Zhao

Recently, Brouwer, Cioab\u{a}, Ihringer and McGinnis obtained some new results involving the eigenvalues of various graphs coming from association schemes and posed some conjectures related to the eigenvalues of Grassmann graphs, bilinear…

Combinatorics · Mathematics 2021-02-23 Sebastian M. Cioabă , Himanshu Gupta

This paper proposes a metric to measure the dissimilarity between graphs that may have a different number of nodes. The proposed metric extends the generalised optimal subpattern assignment (GOSPA) metric, which is a metric for sets, to…

Social and Information Networks · Computer Science 2024-08-28 Jinhao Gu , Ángel F. García-Fernández , Robert E. Firth , Lennart Svensson

We study some basic properties and examples of Hermitian metrics on complex manifolds whose traces of the curvature of the Chern connection are proportional to the metric itself.

Differential Geometry · Mathematics 2020-07-22 Daniele Angella , Simone Calamai , Cristiano Spotti