Exploració per tema "Degree/diameter problem"

Ara es mostren els items 1-7 de 7

    • A new general family of mixed graphs 

      Dalfó Simó, Cristina (2019-01-11)
      Article
      Accés obert
      A new general family of mixed graphs is presented, which generalizes both the pancake graphs and the cycle prefix digraphs. The obtained graphs are vertex transitive and, for some values of the parameters, they constitute ...

    • Almost Moore and the largest mixed graphs of diameters two and three 

      Dalfó Simó, Cristina; Fiol Mora, Miquel Àngel; López Lorenzo, Nacho (Elsevier, 2024-01-01)
      Article
      Accés obert
      Almost Moore mixed graphs appear in the context of the degree/diameter problem as a class of extremal mixed graphs, in the sense that their order is one unit less than the Moore bound for such graphs. The problem of their ...

    • An improved Moore bound and some new optimal families of mixed Abelian Cayley graphs 

      Dalfó Simó, Cristina; Fiol Mora, Miquel Àngel; López Lorenzo, Nacho; Ryan, Joe (2020-10)
      Article
      Accés obert
      We consider the case in which mixed graphs (with both directed and undirected edges) are Cayley graphs of Abelian groups. In this case, some Moore bounds were derived for the maximum number of vertices that such graphs can ...

    • An improved upper bound for the order of mixed graphs 

      Dalfó Simó, Cristina; Fiol Mora, Miquel Àngel; López Lorenzo, Nacho (2018-07)
      Article
      Accés obert
      A mixed graph G can contain both (undirected) edges and arcs (directed edges). Here we derive an improved Moore-like bound for the maximum number of vertices of a mixed graph with diameter at least three. Moreover, a ...

    • Multipartite Moore digraphs 

      Fiol Mora, Miquel Àngel; Gimbert, Joan; Miller, M. (2006-04)
      Article
      Accés obert
      We 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 ...

    • On bipartite-mixed graphs 

      Dalfó Simó, Cristina; Fiol Mora, Miquel Àngel; López Lorenzo, Nacho (Wiley, 2018-04-24)
      Article
      Accés obert
      Mixed 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 ...

    • Sequence mixed graphs 

      Dalfó Simó, Cristina; Fiol Mora, Miquel Àngel; López, Nacho (2016-12)
      Article
      Accés obert
      A mixed graph can be seen as a type of digraph containing some edges (or two opposite arcs). Here we introduce the concept of sequence mixed graphs, which is a generalization of both sequence graphs and literated line ...