DMGT

ISSN 1234-3099 (print version)

ISSN 2083-5892 (electronic version)

https://doi.org/10.7151/dmgt

Discussiones Mathematicae Graph Theory

Journal Impact Factor (JIF 2022): 0.7

5-year Journal Impact Factor (2022): 0.7

CiteScore (2022): 1.9

SNIP (2022): 0.902

Discussiones Mathematicae Graph Theory

Article in volume


Authors:

C. Duffy

Christopher Duffy

Department of Mathematics and Statistics
University of Saskatchewan

email: christopher.duffy@unimelb.edu.au

T. Mullen

Todd Mullen

Saint Francis Xavier University

email: toddmullen26@outlook.com

0000-0003-2818-2734

Title:

An analogue of quasi-transitivity for edge-coloured graphs

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Source:

Discussiones Mathematicae Graph Theory 44(3) (2024) 1189-1215

Received: 2021-12-02 , Revised: 2023-02-24 , Accepted: 2023-02-24 , Available online: 2023-04-19 , https://doi.org/10.7151/dmgt.2494

Abstract:

We extend the notion of quasi-transitive orientations of graphs to 2-edge-coloured graphs. By relating quasi-transitive $2$-edge-colourings to an equivalence relation on the edge set of a graph, we classify those graphs that admit a quasi-transitive $2$-edge-colouring. As a contrast to Ghouilá-Houri's classification of quasi-transitively orientable graphs as comparability graphs, we find quasi-transitively $2$-edge-colourable graphs do not admit a forbiddden subgraph characterization. Restricting the problem to comparability graphs, we show that the family of uniquely quasi-transitively orientable comparability graphs is exactly the family of comparabilty graphs that admit no quasi-transitive $2$-edge-colouring.

Keywords:

oriented graph, quasi-transitivity, edge colouring, uniquely quasi-transitively colourable graphs

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