Výsledky vyhledávání - "Penjić, Safet"

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On Hoffman polynomials of $\lambda$-doubly stochastic irreducible matrices and commutative association schemes

Let $\Gamma$ denote a finite (strongly) connected regular (di)graph with adjacency matrix $A$. The {\em Hoffman polynomial} $h(t)$ of $\Gamma=\Gamma(A)$ is the unique polynomial of smallest degree satisfying $h(A)=J$, where $J$ denotes the all-ones m

Externí odkaz: http://arxiv.org/abs/2403.00652

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On commutative association schemes and associated (directed) graphs

Autor: Monzillo, Giusy, Penjić, Safet

Let ${\cal M}$ denote the Bose--Mesner algebra of a commutative $d$-class association scheme ${\mathfrak X}$ (not necessarily symmetric), and $\Gamma$ denote a (strongly) connected (directed) graph with adjacency matrix $A$. Under the assumption that

Externí odkaz: http://arxiv.org/abs/2307.11680

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On (almost) $2$-$Y$-homogeneous distance-biregular graphs

Autor: Fernandez, Blas, Penjic, Safet

Let $\Gamma$ denote a bipartite graph with vertex set $X$, color partitions $Y$, $Y'$, and assume that every vertex in $Y$ has eccentricity $D\ge 3$. For $z\in X$ and a non-negative integer $i$, let $\Gamma_{i}(z)$ denote the set of vertices in $X$ t

Externí odkaz: http://arxiv.org/abs/2201.05569

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On certain regular nicely distance-balanced graphs

Autor: Fernandez, Blas, Miklavič, Štefko, Penjić, Safet

A connected graph $\G$ is called {\em nicely distance--balanced}, whenever there exists a positive integer $\gamma=\gamma(\G)$, such that for any two adjacent vertices $u,v$ of $\G$ there are exactly $\gamma$ vertices of $\G$ which are closer to $u$

Externí odkaz: http://arxiv.org/abs/2105.10655

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On symmetric association schemes and associated quotient-polynomial graphs

Autor: Fiol, M. A., Penjić, Safet

Let $\Gamma$ denote an undirected, connected, regular graph with vertex set $X$, adjacency matrix $A$, and ${d+1}$ distinct eigenvalues. Let ${\mathcal A}={\mathcal A}(\Gamma)$ denote the subalgebra of Mat$_X({\mathbb C})$ generated by $A$. We refer

Externí odkaz: http://arxiv.org/abs/2009.05343

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On a version of the spectral excess theorem

Autor: Fiol, M. A., Penjić, Safet

Given a regular (connected) graph $\Gamma=(X,E)$ with adjacency matrix $A$, $d+1$ distinct eigenvalues, and diameter $D$, we give a characterization of when its distance matrix $A_D$ is a polynomial in $A$, in terms of the adjacency spectrum of $\Gam

Externí odkaz: http://arxiv.org/abs/1906.01307

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