Browsing by Author "Miller, Mirka"
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A family of mixed graphs with large order and diameter 2
Araujo Pardo, Gabriela; Balbuena Martínez, Maria Camino Teófila; Miller, Mirka; Zdimalova, Maria (201702)
Article
Open AccessA mixed regular graph is a connected simple graph in which each vertex has both a fixed outdegree (the same indegree) and a fixed undirected degree. A mixed regular graphs is said to be optimal if there is not a mixed ... 
An algebraic approach to lifts of digraphs
Dalfó Simó, Cristina; Fiol Mora, Miquel Àngel; Miller, Mirka; Ryan, Joe; Siran, Josef (20190930)
Article
Restricted access  publisher's policyWe study the relationship between two key concepts in the theory of (di)graphs: the quotient digraph, and the lift Ga of a base (voltage) digraph. These techniques contract or expand a given digraph in order to study its ... 
An overview of the degree/diameter problem for directed, undirected and mixed graphs
Miller, Mirka (Iniciativa Digital Politècnica, 2011)
Conference report
Open AccessA wellknown fundamental problem in extremal graph theory is the degree/diameter problem, which is to determine the largest (in terms of the number of vertices) graphs or digraphs or mixed graphs of given maximum degree, ... 
An overview of the Degree/Diameter Problem for directed, undirected and mixed graphs
Miller, Mirka (20100611)
Audiovisual
Open Access 
Approximate results for rainbow labelings
Lladó Sánchez, Ana M.; Miller, Mirka (201703)
Article
Open AccessA simple graph G=(V,E) is said to be antimagic if there exists a bijection f:E¿[1,E] such that the sum of the values of f on edges incident to a vertex takes different values on distinct vertices. The graph G is distance ... 
On quotient digraphs and voltage digraphs
Dalfó Simó, Cristina; Fiol Mora, Miquel Àngel; Miller, Mirka; Ryan, Joe (2016)
External research report
Open AccessIn 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
Dalfó Simó, Cristina; Fiol Mora, Miquel Àngel; Miller, Mirka; Ryan, Joe (201710)
Article
Open AccessWe 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 the nonexistence of almost Moore digraphs
Conde Colom, Josep; Gimbert Quintilla, Joan; González Rovira, Josep; Miller, Mirka; Miret Biosca, Josep Maria (20140701)
Article
Restricted access  publisher's policyDigraphs of maximum outdegree at most d > 1, diameter at most k > 1 and order N(d, k) = d + ... + d(k) are called almost Moore or (d, k)digraphs. So far, the problem of their existence has been solved only when d = 2, 3 ...