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We analyze spectral properties of a quantum graph in the form of a ring chain with a $\delta$ coupling in the vertices exposed to a homogeneous magnetic field perpendicular to the graph plane. We find the band spectrum in the case when the…

Mathematical Physics · Physics 2019-12-10 Pavel Exner , Stepan S. Manko

We present near-optimal algorithms for detecting small vertex cuts in the CONGEST model of distributed computing. Despite extensive research in this area, our understanding of the vertex connectivity of a graph is still incomplete,…

Data Structures and Algorithms · Computer Science 2023-06-21 Merav Parter , Asaf Petruschka

This paper studies the problem of recovering a hidden vertex correspondence between two correlated graphs when both edge weights and node features are observed. While most existing work on graph alignment relies primarily on edge…

Statistics Theory · Mathematics 2026-04-07 Dong Huang , Chenyang Tian , Pengkun Yang

We study a family of closed quantum graphs described by one singular vertex of order n=4. By suitable choice of the parameters specifying the singular vertex, we can construct a closed sequence of paths in the parameter space that…

Mathematical Physics · Physics 2016-08-11 Taksu Cheon , Atushi Tanaka , Ondřej Turek

This work deals with quantum graphs, focusing on the transmission properties they engender. We first select two simple diamond graphs, and two hexagonal graphs in which the vertices are all of degree 3, and investigate their transmission…

Quantum Physics · Physics 2019-12-17 A. Drinko , F. M. Andrade , D. Bazeia

A topological graph drawn on a cylinder whose base is horizontal is \emph{angularly monotone} if every vertical line intersects every edge at most once. Let $c(n)$ denote the maximum number $c$ such that every simple angularly monotone…

Combinatorics · Mathematics 2013-07-17 Radoslav Fulek

We investigate the terminal-pairibility problem in the case when the base graph is a complete bipartite graph, and the demand graph is also bipartite with the same color classes. We improve the lower bound on maximum value of $\Delta(D)$…

Combinatorics · Mathematics 2020-04-22 Lucas Colucci , Péter L. Erdős , Ervin Győri , Tamás Róbert Mezei

We discuss the question whether the existence of perfect matchings in a cubic graph can be seen from the spectrum of its adjacency matrix. For regular graphs in general and for three edge-disjoint perfect matchings in a cubic graph (that…

Combinatorics · Mathematics 2026-01-08 Willem H. Haemers

We consider functional-integral quantisation of the moduli of all quantum metrics defined as square-lengths $a$ on the edges of a Lorentzian square graph. We determine correlation functions and find a fixed relative uncertainty $\Delta…

General Relativity and Quantum Cosmology · Physics 2020-01-08 Shahn Majid

The paper considers the NP-hard graph vertex coloring problem, which differs from traditional problems in which it is required to color vertices with a given (or minimal) number of colors so that adjacent vertices have different colors. In…

Discrete Mathematics · Computer Science 2025-02-24 Adil Erzin , Roman Plotnikov , Georgii Zhukov

Quantum repeater networks are a fundamental of any future quantum Internet and long-distance quantum communications. The entangled quantum nodes can communicate through several different levels of entanglement, leading to a heterogeneous,…

Quantum Physics · Physics 2018-08-24 Laszlo Gyongyosi , Sandor Imre

Graph matching, also known as network alignment, refers to finding a bijection between the vertex sets of two given graphs so as to maximally align their edges. This fundamental computational problem arises frequently in multiple fields…

Data Structures and Algorithms · Computer Science 2021-08-10 Cheng Mao , Mark Rudelson , Konstantin Tikhomirov

We investigate the problem of constructing planar drawings with few bends for two related problems, the partially embedded graph problem---to extend a straight-line planar drawing of a subgraph to a planar drawing of the whole graph---and…

Computational Geometry · Computer Science 2014-10-31 Timothy M. Chan , Fabrizio Frati , Carsten Gutwenger , Anna Lubiw , Petra Mutzel , Marcus Schaefer

We prove that after an arbitrarily small adjustment of edge lengths, the spectrum of a compact quantum graph with $\delta$-type vertex conditions can be simple. We also show that the eigenfunctions, with the exception of those living…

Mathematical Physics · Physics 2016-06-27 Gregory Berkolaiko , Wen Liu

It is known that the vertex connectivity of a planar graph can be computed in linear time. We extend this result to the class of locally maximal 1-plane graphs: graphs that have an embedding with at most one crossing per edge such that the…

Combinatorics · Mathematics 2021-12-14 Therese Biedl , Karthik Murali

We define a notion of quantum automorphism group of Graph C*-algebras for finite, connected graphs. Under the assumption that the underlying graph does not have any multiple edge or loop, the quantum automorphism group of underlying…

Operator Algebras · Mathematics 2018-10-11 Soumalya Joardar , Arnab Mandal

We study the problem of deleting a minimum cost set of vertices from a given vertex-weighted graph in such a way that the resulting graph has no induced path on three vertices. This problem is often called cluster vertex deletion in the…

Data Structures and Algorithms · Computer Science 2019-02-25 Samuel Fiorini , Gwenaël Joret , Oliver Schaudt

Diverse facets Of the Theory of Quantum Walks on Graph are reviewed Till now .In specific, Quantum network routing, Quantum Walk Search Algorithm, Element distinctness associated to the eigenvalues of Graphs and the use of these relation…

Data Structures and Algorithms · Computer Science 2018-02-01 Tewabe Chekole

All the work made so far on edge-covering a graph by cliques focus on finding the minimum number of cliques that cover the graph. On this paper, we fix the number of cliques that cover a graph by the same number of vertices that the graph…

Combinatorics · Mathematics 2017-03-09 Leopoldo Taravilse

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