3 citations · 8 across the 9 of their papers we have counts for
11 papers
A procedure to obtain symmetric cycles of any odd length using directed Hajós constructions
Juan Carlos García-Altamirano, Mika Olsen, Jorge Cervantes-Ojeda
The dichromatic number of a digraph is the minimum number of colors of a vertex coloring of such that has no monochromatic cycles. The Hajós join were recently extended…
How to construct the symmetric cycle of length 5 using Hajós construction with an adapted Rank Genetic Algorithm
Juan Carlos García-Altamirano, Mika Olsen, Jorge Cervantes-Ojeda
In 2020 Bang-Jensen et. al. generalized the Hajós join of two graphs to the class of digraphs and generalized several results for vertex colorings in digraphs. Although, as a conse…
On the harmonious chromatic number of graphs
Gabriela Araujo-Pardo, Juan José Montellano-Ballesteros, Mika Olsen +1
The harmonious chromatic number of a graph is the minimum number of colors that can be assigned to the vertices of in a proper way such that any two distinct edges have dif…
Zykov sums of digraphs with diachromatic number equal to their harmonious number
Mika Olsen, Christian Rubio-Montiel, Alejandra Silva-Ramírez
The dichromatic number and the diachromatic number are generalizations of the chromatic number and the achromatic number for digraphs considering acyclic colorings. In this paper,…
The digrundy number of digraphs
Gabriela Araujo-Pardo, Juan José Montellano-Ballesteros, Mika Olsen +1
We extend the Grundy number and the ochromatic number, parameters on graph colorings, to digraph colorings, we call them {\emph{digrundy number}} and {\emph{diochromatic number}},…
Conditions on the regularity of balanced -partite tournaments for the existence of strong subtournaments with high minimum degree
Ana Paulina Figueroa, Juan José Montellano-Ballesteros, Mika Olsen
We consider the following problem posed by Volkmann in 2007: How close to regular must a c-partite tournament be, to secure a strongly connected subtournament of order ? We give…
Achromatic number, achromatic index and diachromatic number of circulant graphs and digraphs
Gabriela Araujo-Pardo, Juan Jos{\' e} Montellano-Ballesteros, Mika Olsen +1
In this paper, we determine the achromatic and diachromatic numbers of some circulant graphs and digraphs each one with two lengths and give bounds for other circulant graphs and d…
On the packing chromatic number of Moore graphs
Julián Fresán-Figueroa, Diego González-Moreno, Mika Olsen
The \emph{packing chromatic number } of a graph is the smallest integer for which there exists a vertex coloring such that an…
Decomposition of balanced multipartite tournaments into strongly connected tournaments
A. P. Figueroa, J. J. Montellano-Ballesteros, M. Olsen
Decomposing a digraph into subdigraphs with a fixed structure or property is a classical problem in graph theory and a useful tool in a number of applications of networks and commu…
The diachromatic number of digraphs
Gabriela Araujo-Pardo, Juan José Montellano-Ballesteros, Mika Olsen +1
We consider the extension to directed graphs of the concept of achromatic number in terms of acyclic vertex colorings. The achromatic number have been intensely studied since it wa…
Solving the kernel perfect problem by (simple) forbidden subdigraphs for digraphs in some families of generalized tournaments and generalized bipartite tournaments
H. Galeana-Sánchez, M. Olsen
A digraph such that every proper induced subdigraph has a kernel is said to be \emph{kernel perfect} (KP for short) (\emph{critical kernel imperfect} (CKI for short) resp.) if the…