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Abstract
A 2-dominating set of a graph G is a set D of vertices of G such that every vertex not in D has a at least two neighbors in D. The 2-domination number of a graph G, denoted by gamma_2(G), is the minimum cardinality of a 2-dominating set of G. Fink and Jacobson [n-domination in graphs, Graph theory with applications to algorithms and computer science, Wiley, New York, 1985, 283-300] established the following lower bound on the 2-domination number of a tree in term of its order, gamma_2(T) >= (n+1)/2. We give an alternative proof of this bound.
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- Category:
- Articles
- Type:
- artykuły w czasopismach
- Published in:
-
International Journal of Modern Mathematical Sciences
no. 5,
pages 325 - 326,
ISSN: - Language:
- English
- Publication year:
- 2010
- Bibliographic description:
- Krzywkowski M.: An Alternative Proof of a Lower Bound on the 2-Domination Number of a Tree// International Journal of Modern Mathematical Sciences -Vol. 5,iss. 3 (2010), s.325-326
- Verified by:
- Gdańsk University of Technology
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