Exploració per autor "Fiol Mora, Miquel Àngel"
Ara es mostren els items 71-90 de 139
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Measures of edge-uncolorability of cubic graphs
(2018-12-21)
Article
Accés obertThere are many hard conjectures in graph theory, like Tutte’s 5-flow conjecture, and the 5-cycle double cover conjecture, which would be true in general if they would be true for cubic graphs. Since most of them are trivially ... -
Moments in graphs
(2013)
Article
Accés obertLet G be a connected graph with vertex set V and a weight function that assigns a nonnegative number to each of its vertices. Then, the -moment of G at vertex u is de ned to be M G(u) = P v2V (v) dist(u; v), where ... -
Moore mixed graphs from Cayley graphs
(2023-03-25)
Article
Accés obertA Moore (r, z, k)-mixed graph G has every vertex with undirected degree r, directed in- and outdegree z, diameter k, and number of vertices (or order) attaining the corresponding Moore bound M(r, z, k) for mixed graphs. ... -
Multipartite Moore digraphs
(2006-04)
Article
Accés obertWe derive some Moore-like bounds for multipartite digraphs, which extend those of bipartite digraphs, under the assumption that every vertex of a given partite set is adjacent to the same number $\delta$ of vertices in ... -
New Moore-like bounds and some optimal families of abelian Cayley mixed graphs
(2020-06)
Article
Accés obertMixed graphs can be seen as digraphs that have both arcs and edges (or digons, that is, two opposite arcs). In this paper, we consider the case where such graphs are Cayley graphs of Abelian groups. Such groups can be ... -
New results for the Mondrian art problem
(2021-04-15)
Article
Accés obertThe Mondrian problem consists of dissecting a square of side length into non-congruent rectangles with natural length sides such that the difference between the largest and the smallest areas of the rectangles partitioning ... -
Number of walks and degree powers in a graph
(2006-04)
Article
Accés obertThis letter deals with the relationship between the total number of k-walks in a graph, and the sum of the k-th powers of its vertex degrees. In particular, it is shown that the sum of all k-walks is upper bounded by the ... -
On Almost Distance-Regular Graphs
(2010-03-12)
Report de recerca
Accés obert -
On almost distance-regular graphs
(2010)
Article
Accés restringit per política de l'editorialDistance-regular graphs are a key concept in Algebraic Combinatorics and have given rise to several generalizations, such as association schemes. Motivated by spectral and other algebraic characterizations of distance-regular ... -
On bipartite-mixed graphs
(Wiley, 2018-04-24)
Article
Accés obertMixed graphs can be seen as digraphs that have both arcs and edges (or digons, that is, two opposite arcs). In this paper, we consider the case where such graphs are bipartite. As main results, we show that in this context ... -
On congruence in $Z^n$ and the dimension of a multidimensional circulant
(Elsevier, 1995)
Article
Accés obertFrom a generalization to $Z^n$ of the concept of congruence we define a family of regular digraphs or graphs called multidimensional circulants, which turn to be Cayley (di)graphs of Abelian groups. This paper is mainly ... -
On d-Fibonacci digraphs
(2021-10-03)
Article
Accés obertThe d-Fibonacci digraphs F(d, k), introduced here, have the number of vertices following some generalized Fibonacci-like sequences. They can be defined both as digraphs on alphabets and as iterated line digraphs. Here we ... -
On inertia and ratio type bounds for the k-independence number of a graph and their relationship
(Elsevier, 2023-07-15)
Article
Accés obertFor , the -independence number of a graph is the maximum number of vertices that are mutually at distance greater than . The well-known inertia and ratio bounds for the (1-)independence number of a graph, due to Cvetković ... -
On k-Walk-Regular Graphs
(2008-08)
Article
Accés obertConsidering a connected graph $G$ with diameter $D$, we say that it is \emph{$k$-walk-regular}, for a given integer $k$ $(0\leq k \leq D)$, if the number of walks of length $\ell$ between vertices $u$ and $v$ only depends ... -
On middle cube graphs
(2015)
Article
Accés obertWe study a family of graphs related to the $n$-cube. The middle cube graph of parameter k is the subgraph of $Q_{2k-1}$ induced by the set of vertices whose binary representation has either $k-1$ or $k$ number of ones. The ... -
On outindependent subgraphs of strongly regular graphs
(Taylor & Francis, 2006)
Article
Accés obertAn outindependent subgraph of a graph G, with respect to an independent vertex subset C¿¿V, is the subgraph GC induced by the vertices in V\¿C. We study the case when G is strongly regular, where the results of de Caen ... -
On quotient digraphs and voltage digraphs
(2016)
Report de recerca
Accés obertIn this note we present a general approach to construct large digraphs from small ones. These are called expanded digraphs, and, as particular cases, we show their close relationship between voltage digraphs and line ... -
On quotient digraphs and voltage digraphs
(2017-10)
Article
Accés obertWe study the relationship between two key concepts in the theory of digraphs, those of quotient digraphs and voltage digraphs. These techniques contract or expand a given digraph in order to study its characteristics,or ... -
On some groups related to arc-colored digraphs
(Mediterranean press, 1988)
Comunicació de congrés
Accés obertAn arc-coloring of a digraph G is an assignation of colors to its arcs in such a way that all arcs incident to each vertex, as well as all arcs incident from each vertex, have different colors. In an arc-colored d-regular ... -
On symmetric association schemes and associated quotient-polynomial graphs
(2021-01-01)
Article
Accés obertLet denote an undirected, connected, regular graph with vertex set , adjacency matrix , and distinct eigenvalues. Let denote the subalgebra of generated by . We refer to as the adjacency algebra of . In this paper we ...
