DMGT

ISSN 1234-3099 (print version)

ISSN 2083-5892 (electronic version)

https://doi.org/10.7151/dmgt

Discussiones Mathematicae Graph Theory

IMPACT FACTOR 2018: 0.741

SCImago Journal Rank (SJR) 2018: 0.763

Rejection Rate (2017-2018): c. 84%

Discussiones Mathematicae Graph Theory

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Discussiones Mathematicae Graph Theory 20(1) (2000) 39-56
DOI: 10.7151/dmgt.1105

RECOGNIZING WEIGHTED DIRECTED CARTESIAN GRAPH BUNDLES

Blaz Zmazek

Department of Mathematics, PEF, University of Maribor
Koroska 160, si-2000 Maribor, Slovenia
e-mail: blaz.zmazek@uni-mb.si

Janez Zerovnik*

FME, University of Maribor
Smetanova 17, si-2000 Maribor, Slovenia
e-mail: janez.zerovnik@imfm.uni-lj.si

Abstract

In this paper we show that methods for recognizing Cartesian graph bundles can be generalized to weighted digraphs. The main result is an algorithm which lists the sets of degenerate arcs for all representations of digraph as a weighted directed Cartesian graph bundle over simple base digraphs not containing transitive tournament on three vertices. Two main notions are used. The first one is the new relation δ*defined among the arcs of a digraph as a weighted directed analogue of the well-known relation δ*. The second one is the concept of half-convex subgraphs. A subgraph H is half-convex in G if any vertex x ∈ G∖H has at most one predecessor and at most one successor.

Keywords: graph bundles, Cartesian graph product, weighted digraphs, half-convexity.

1991 Mathematics Subject Classification: 05C60.

References

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Received 8 January 1999
Revised 16 March 2000