55 citations · 103 across the 30 of their papers we have counts for
9 papers · 2 filters
An algebraic approach to lifts of digraphs
C. Dalfó, M. A. Fiol, M. Miller +2
We study the relationship between two key concepts in the theory of (di)graphs: the quotient digraph, and the lift of a base (voltage) digraph. These techniques contract or e…
On bipartite mixed graphs
C. Dalfó, M. A. Fiol, N. López
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…
An improved Moore bound for mixed graphs
C. Dalfó, M. A. Fiol, N. López
A mixed graph 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 wit…
From expanded digraphs to lifts of voltage digraphs and line digraphs
C. Dalfó, M. A. Fiol, M. Miller +1
In 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 the close relationship…
On middle cube graphs
C. Dalfó, M. A. Fiol, M. Mitjana
We study a family of graphs related to the -cube. The middle cube graph of parameter is the subgraph of induced by the set of vertices whose binary representation…
Sequence mixed graphs
C. Dalfó, M. A. Fiol, N. López
A mixed graph can be seen as a type of digraph containing some edges (two opposite arcs). Here we introduce the concept of sequence mixed graphs, which is a generalization of both…