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Graphs with diverse structural characteristics play a central role in modelling and optimization tasks. The ability to generate different types of graphs that exhibit shared properties is likewise essential for algorithm selection and…

Neural and Evolutionary Computing · Computer Science 2026-03-31 Hendrik Richter , Frank Neumann

For typical cocycles over subshifts of finite type, we show that for any given orbit segment, we can construct a periodic orbit such that it shadows the given orbit segment and that the product of the cocycle along its orbit is a proximal…

Dynamical Systems · Mathematics 2022-01-25 Kiho Park

This paper gives various methods for constructing vector bundles over elliptic curves and more generally over families of elliptic curves. We construct universal families over generalized elliptic curves via spectral cover methods and also…

alg-geom · Mathematics 2008-02-03 Robert Friedman , John W. Morgan , Edward Witten

In order to obtain perfect state transfer between two sites in a network of interacting qubits, their corresponding vertices in the underlying graph must satisfy a combinatorial property called strong cospectrality. Here we determine the…

Combinatorics · Mathematics 2018-05-23 Gabriel Coutinho

We present methods for obtaining new solutions to the bispectral problem. We achieve this by giving its abstract algebraic version suitable for generalizations. All methods are illustrated by new classes of bispectral operators.

q-alg · Mathematics 2009-10-30 B. Bakalov , E. Horozov , M. Yakimov

Motivated by discrete Laplacian differential operators with various accuracy orders in numerical analysis, we introduce new matrices attached to a simple graph that can be considered graph Laplacians with higher accuracy. In particular, we…

Combinatorics · Mathematics 2025-04-09 Mary Yoon

Here, we define a subdivision operation for a hypergraph and compute all the eigenvalues of the subdivision of regular and certain non-regular hypergraphs. In non-regular hypergraphs, we investigate the power of regular graphs, various…

Combinatorics · Mathematics 2023-07-26 Anirban Banerjee , Arpita Das

The aim of the present article is to give an overview of spectral theory on metric graphs guided by spectral geometry on discrete graphs and manifolds. We present the basic concept of metric graphs and natural Laplacians acting on it and…

Combinatorics · Mathematics 2008-02-15 Olaf Post

The distance matrix $\mathcal{D}(G)$ of a graph $G$ is the matrix containing the pairwise distances between vertices, and the distance Laplacian matrix is $\mathcal{D}^L(G)=T(G)-\mathcal{D}(G)$, where $T(G)$ is the diagonal matrix of row…

Combinatorics · Mathematics 2018-12-17 Boris Brimkov , Ken Duna , Leslie Hogben , Kate Lorenzen , Carolyn Reinhart , Sung-Yell Song , Mark Yarrow

The search for a highly discriminating and easily computable invariant to distinguish graphs remains a challenging research topic. Here we focus on cospectral graphs whose complements are also cospectral (generalized cospectral), and on…

Combinatorics · Mathematics 2023-04-17 Aida Abiad , Carlos A. Alfaro , Ralihe R. Villagrán

We study some spectral properties of a matrix that is constructed as a combination of a Laplacian and an adjacency matrix of simple graphs. The matrix considered depends on a positive parameter, as such we consider the implications in…

Dynamical Systems · Mathematics 2024-08-02 Riccardo Bonetto , Hildeberto Jardón Kojakhmetov

Laplacian operators on finite compact metric graphs are considered under the assumption that matching conditions at graph vertices are of $\delta$ and $\delta'$ types. An infinite series of trace formulae is obtained which link together two…

Spectral Theory · Mathematics 2014-11-06 Yulia Ershova , Irina I. Karpenko , Alexander V. Kiselev

Let $M\circ N$ denote the Schur product of two matrices $M$ and $N$. A graph $X$ with adjacency matrix $A$ is walk regular if $A^k\circ I$ is a constant times $I$ for each $k\ge0$, and $X$ is 1-walk-regular if it is walk regular and…

Combinatorics · Mathematics 2025-01-28 Chris Godsil , Wanting Sun , Xiaohong Zhang

Omnidirectional cameras are widely used in such areas as robotics and virtual reality as they provide a wide field of view. Their images are often processed with classical methods, which might unfortunately lead to non-optimal solutions as…

Computer Vision and Pattern Recognition · Computer Science 2017-07-27 Renata Khasanova , Pascal Frossard

Extending a classic result of Johnson and Newman, this paper provides a matrix characterization for two generalized cospectral graphs with a pair of generalized cospectral vertex-deleted subgraphs. As an application, we present a new…

Combinatorics · Mathematics 2024-08-06 Wei Wang , Wenqiang Wen , Songlin Guo

Spectral hypergraph theory studies the structural properties of a hypergraph that can be inferred from the eigenvalues and the eigenvectors of either matrices or tensors associated with it. In this paper we study the spectral…

Combinatorics · Mathematics 2026-04-08 Aida Abiad , Joshua Cooper , Utku Okur

We obtain new bounds for the Laplacian spectral radius of a signed graph. Most of these new bounds have a dependence on edge sign, unlike previously known bounds, which only depend on the underlying structure of the graph. We then use some…

Combinatorics · Mathematics 2011-03-25 Nathan Reff

We investigate the relationship between the structure of a discrete graphical model and the support of the inverse of a generalized covariance matrix. We show that for certain graph structures, the support of the inverse covariance matrix…

Machine Learning · Statistics 2014-01-07 Po-Ling Loh , Martin J. Wainwright

Learning a graph with a specific structure is essential for interpretability and identification of the relationships among data. It is well known that structured graph learning from observed samples is an NP-hard combinatorial problem. In…

Machine Learning · Statistics 2019-09-26 Sandeep Kumar , Jiaxi Ying , Jos'e Vin'icius de M. Cardoso , Daniel P. Palomar

We address the Laplacian on a perturbed periodic graph which might not be a periodic graph. We present a class of perturbed graphs for which the essential spectra of the Laplacians are stable even when the graphs are perturbed by adding and…

Mathematical Physics · Physics 2015-10-01 Itaru Sasaki , Akito Suzuki