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In this article we study asymptotic slopes of strongly semistable vector bundles on a smooth projective surface. A connection between asymptotic slopes and strong restriction theorem of a strongly semistable vector bundle is shown. We also…

Algebraic Geometry · Mathematics 2022-01-10 Mitra Koley , A. J. Parameswaran

A mixed extension of a graph $G$ is a graph $H$ obtained from $G$ by replacing each vertex of $G$ by a clique or a coclique, whilst two vertices in $H$ corresponding to distinct vertices $x$ and $y$ of $G$ are adjacent whenever $x$ and $y$…

Combinatorics · Mathematics 2019-07-23 Willem H. Haemers , Sezer Sorgun , Hatice Topcu

A covariance graph is an undirected graph associated with a multivariate probability distribution of a given random vector where each vertex represents each of the different components of the random vector and where the absence of an edge…

Probability · Mathematics 2009-12-15 Dhafer Malouche , Bala Rajaratnam

A fundamental and challenging problem in spectral graph theory is to characterize which graphs are uniquely determined by their spectra. In Wang [J. Combin. Theory, Ser. B, 122 (2017): 438-451], the author proved that an $n$-vertex graph…

Combinatorics · Mathematics 2024-10-04 Wei Wang , Wei Wang , Fuhai Zhu

We study scattering quantum walks on highly symmetric graphs and use the walks to solve search problems on these graphs. The particle making the walk resides on the edges of the graph, and at each time step scatters at the vertices. All of…

Quantum Physics · Physics 2009-01-27 Daniel Reitzner , Mark Hillery , Edgar Feldman , Vladimir Buzek

The spectrum of the $k$-power hypergraph of a graph $G$ is called the $k$-ordered spectrum of $G$.If graphs $G_1$ and $G_2$ have same $k$-ordered spectrum for all positive integer $k\geq2$, $G_1$ and $G_2$ are said to be high-ordered…

Combinatorics · Mathematics 2021-11-09 Lixiang Chen , Lizhu Sun , Changjiang Bu

Boundary conditions in quantum graph vertices are generally given in terms of a unitary matrix $U$. Observing that if $U$ has at most two eigenvalues, then the scattering matrix $\mathcal{S}(k)$ of the vertex is a linear combination of the…

Mathematical Physics · Physics 2011-10-06 Ondřej Turek , Taksu Cheon

A graph is called a strong (resp. weak) bar 1-visibility graph if its vertices can be represented as horizontal segments (bars) in the plane so that its edges are all (resp. a subset of) the pairs of vertices whose bars have a…

Data Structures and Algorithms · Computer Science 2013-12-20 William Evans , Michael Kaufmann , William Lenhart , Giuseppe Liotta , Tamara Mchedlidze , Stephen Wismath

Mutual-visibility sets were motivated by visibility in distributed systems and social networks, and intertwine with several classical mathematical areas. Monotone properties of the variety of mutual-visibility sets, and restrictions of such…

Combinatorics · Mathematics 2025-12-10 Csilla Bujtás , Sandi Klavžar , Jing Tian

We study regular graphs whose distance-$2$ graph or distance-$1$-or-$2$ graph is strongly regular. We provide a characterization of such graphs $\Gamma$ (among regular graphs with few distinct eigenvalues) in terms of the spectrum and the…

Combinatorics · Mathematics 2019-02-28 C. Dalfó , M. A. Fiol , J. Koolen

For any graph~\(G,\) a set of vertices~\({\cal V}\) is said to be dominating if every vertex of~\(G\) contains at least one node of~\(G\) and separating if each vertex~\(v\) contains a unique neighbour~\(u_v \in {\cal V}\) that is adjacent…

Combinatorics · Mathematics 2021-08-17 Ghurumuruhan Ganesan

A regular graph is co-edge regular if there exists a constant $\mu$ such that any two distinct and non-adjacent vertices have exactly $\mu$ common neighbors. In this paper, we show that for integers $s\ge 2$ and $n$ large enough, any…

Combinatorics · Mathematics 2019-08-09 Ying-Ying Tan , Jack H. Koolen , Zheng-Jiang Xia

Properties of graphs that can be characterized by the spectrum of the adjacency matrix of the graph have been studied systematically recently. Motivated by the complexity of these properties, we show that there are such properties for which…

Combinatorics · Mathematics 2020-01-28 Omid Etesami , Willem H. Haemers

We introduce a new variant of the coarse Baum-Connes conjecture designed to tackle coarsely disconnected metric spaces called the boundary coarse Baum-Connes conjecture. We prove this conjecture for many coarsely disconnected spaces that…

K-Theory and Homology · Mathematics 2014-07-23 Martin Finn-Sell , Nick Wright

Let $G(V, E)$ be a finite, simple, isolate-free graph. A set $D$ of vertices of a graph $G$ with the vertex set $V$ is a double dominating set of $G$, if every vertex $v\in D$ has at least one neighbor in $D$ and every vertex $v \in V…

Combinatorics · Mathematics 2024-08-01 Hamidreza Golmohammadi

Coalescing involves gluing one or more rooted graphs onto another graph. Under specific conditions, it is possible to start with cospectral graphs that are coalesced in similar ways that will result in new cospectral graphs. We present a…

Combinatorics · Mathematics 2024-04-03 Sajid Bin Mahamud , Steve Butler , Hannah Graff , Nick Layman , Taylor Luck , Jiah Jin , Noah Owen , Angela Yuan

We investigate the graph isomorphism (GI) in some cospectral networks. Two graph are isomorphic when they are related to each other by a relabeling of the graph vertices. We want to investigate the GI in two scalable (n + 2)-regular graphs…

Quantum Physics · Physics 2014-12-04 M. A. Jafarizadeh , F. Eghbalifam , S. Nami

Two planar graphs G1 and G2 sharing some vertices and edges are `simultaneously planar' if they have planar drawings such that a shared vertex [edge] is represented by the same point [curve] in both drawings. It is an open problem whether…

Data Structures and Algorithms · Computer Science 2011-12-12 Bernhard Haeupler , Krishnam Raju Jampani , Anna Lubiw

A path in a vertex-colored graph is a {\it vertex-proper path} if any two internal adjacent vertices differ in color. A vertex-colored graph is {\it proper vertex $k$-connected} if any two vertices of the graph are connected by $k$ disjoint…

Combinatorics · Mathematics 2017-05-09 Yingying Zhang , Xiaoyu Zhu

Coarse graph theory concerns finding 'coarse' analogues of graph theory theorems, replacing disjointness with being far apart. One of the most interesting open questions is to find a coarse analogue of Menger's theorem, which characterizes…

Combinatorics · Mathematics 2025-08-21 Tung Nguyen , Alex Scott , Paul Seymour
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