A set S of vertices of a graph G is a total dominating set, if every vertex of V (G) is adjacent to some vertex in S. The total domination number of G, denoted by ฮณ t (G), is the minimum cardinality of a total dominating set of G. We prove that, if G is a graph of order n with minimum degree at leas
Convexity of minimal total dominating functions in graphs
โ Scribed by Yu, Bo
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 122 KB
- Volume
- 24
- Category
- Article
- ISSN
- 0364-9024
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โฆ Synopsis
A total dominating function (TDF) of a graph G = (V, E) is a function f : V โ [0, 1] such that for each v โ V , the sum of f values over the open neighbourhood of v is at least one. Zero-one valued TDFs are precisely the characteristic functions of total dominating sets of G. We study the convexity of minimal total dominating functions. A minimal total dominating function (MTDF) f is called universal if convex combinations of f and any other MTDF are minimal. Generalizing and unifying two previous major results by Cockayne, Mynhardt and Yu in the area, we give a stronger sufficiency condition for an MTDF to be universal. Moreover, we define a splitting operation on a graph G, which preserves the universality. Using the operation, we give many more classes of graphs having a universal MTDF.
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