Let Ξ³(G) and ir(G) denote the domination number and the irredundance number of a graph G, respectively. Allan and Laskar [Proc. 9th Southeast Conf. on Combin., Graph Theory & Comp. (1978) 43-56] and BollobΓ‘s and Cock- ayne [J. Graph Theory (1979) 241-249] proved independently that Ξ³(G) < 2ir(G) for
Vertex criticality for upper domination and irredundance
β Scribed by P. J. P. Grobler; C. M. Mynhardt
- Publisher
- John Wiley and Sons
- Year
- 2001
- Tongue
- English
- Weight
- 104 KB
- Volume
- 37
- Category
- Article
- ISSN
- 0364-9024
- DOI
- 10.1002/jgt.1015
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β¦ Synopsis
Abstract
Let Ο be any of the domination parameters ir Ξ³, i, Ξ², Ξ or IR. The graph G is Οβcritical (Ο^+^βcritical) if the removal of any vertex of G causes Ο(G) to decrease (increase). We show that the classes of IRβcritical and Ξβcritical graphs coincide, and exhibit a class of Ξ^+^βcritical graphs. Β© 2001 John Wiley & Sons, Inc. J Graph Theory 37: 205β212, 2001
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