Zobrazeno 1 - 7
of 7
pro vyhledávání: '"Johanna Wiehe"'
Publikováno v:
AKCE International Journal of Graphs and Combinatorics, Vol 17, Iss 3, Pp 992-994 (2020)
Reed (1987) showed that, if two graphs are P4-isomorphic, then either both are perfect or none of them is. In this note, we will derive an analogous result for perfect digraphs.
Externí odkaz:
https://doaj.org/article/4e24ce3cca934cb78686094340005656
Publikováno v:
AKCE International Journal of Graphs and Combinatorics, Vol 17, Iss 3, Pp 992-994 (2020)
Reed showed that, if two graphs are $P_4$-isomorphic, then either both are perfect or none of them is. In this note we will derive an analogous result for perfect digraphs.
5 pages, 1 figure
5 pages, 1 figure
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::412a907d6fc5663311211f4c82deb029
https://doi.org/10.1016/j.akcej.2019.12.018
https://doi.org/10.1016/j.akcej.2019.12.018
Autor:
Winfried Hochstättler, Johanna Wiehe
Publikováno v:
Trends in Mathematics ISBN: 9783030838225
We define a trivariate polynomial combining the NL-coflow and the NL-flow polynomial, which build a dual pair counting acyclic colorings of directed graphs, in the more general setting of regular oriented matroids.
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::8d2d2792578d28104bb311dd4f36a1a9
https://doi.org/10.1007/978-3-030-83823-2_59
https://doi.org/10.1007/978-3-030-83823-2_59
Autor:
Johanna Wiehe, Winfried Hochstättler
Publikováno v:
AIRO Springer Series ISBN: 9783030630713
An acyclic coloring of a digraph as defined by V. Neumann-Lara is a vertex-coloring such that no monochromatic directed cycles occur. Counting the number of such colorings with k colors can be done by counting so-called Neumann-Lara-coflows (NL-coflo
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::075ac770b39c4b3d63a2abc52ae79b55
https://doi.org/10.1007/978-3-030-63072-0_1
https://doi.org/10.1007/978-3-030-63072-0_1
In 1982 V\'{i}ctor Neumann-Lara introduced the dichromatic number of a digraph $D$ as the smallest integer $k$ such that the vertices $V$ of $D$ can be colored with $k$ colors and each color class induces an acyclic digraph. Later a flow theory for t
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::0ff3c115b3756420faa2ad6467a6e642
This book collects the extended abstracts of the accepted contributions to EuroComb21. A similar book is published at every edition of EuroComb (every two years since 2001) collecting the most recent advances in combinatorics, graph theory, and relat
This book highlights new and original contributions on Graph Theory and Combinatorial Optimization both from the theoretical point of view and from applications in all fields. The book chapters describe models and methods based on graphs, structural