Discussiones Mathematicae Graph Theory 28(1) (2008) 5-21
doi: 10.7151/dmgt.1388

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Martin Sonntag

Faculty of Mathematics and Computer Science
TU Bergakademie Freiberg
Prüferstraße 1, D-09596 Freiberg, Germany
e-mail: sonntag@mathe.tu-freiberg.de

Hanns-Martin Teichert

Institute of Mathematics
University of Lübeck
Wallstraß e 40, D-23560 Lübeck, Germany
e-mail: teichert@math.uni-luebeck.de


If D = (V,A) is a digraph, its competition hypergraph CH(D) has the vertex set V and e ⊆ V is an edge of CH(D) iff |e| ≥ 2 and there is a vertex v ∈ V, such that e = {w ∈ V|(w,v) ∈ A}. We tackle the problem to minimize the number of strong components in D without changing the competition hypergraph CH(D). The results are closely related to the corresponding investigations for competition graphs in Fraughnaugh et al. [3].

Keywords: hypergraph, competition graph, strong component.

2000 Mathematics Subject Classification: 05C65, 05C20, 05C40.


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Received 14 January 2005
Revised 24 September 2007
Accepted 31 December 2007