is one of the most important domination parameters
which was introduced by Cockayne et al. in 1980. In recent years
a variant of total domination number have been extensively studied
namely
total outer connected domination number γtc(G). It is well known that γt(G) ≤ γtc(G). In this paper
we show that if T has no strong support vertex
we have that γtc(T) ≤5γt(T)/2-2. In addition
we provide a constructive characterizations of the trees achieving equality in the bound.
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references
HENNING M A.A survey of selected recent results on total domination in graphs[J].Discrete Mathematics,2009,309:32-63.
CYMAN J.Total outer-connected domination in trees[J].Discussiones Mathematicae Graph Theory,2010,30:377-383.
SHAN E F,KANG L,HENNING M A.A characterization of trees with equal total domination and paired-domination numbers[J].Australasian Journal of Combinatorics,2004,30:31-39.
FAVARON O,KARAMI H,SHEKHOLESLAMI S M.On the total outer-connected domination in graphs[J].Journal of Combinatorial Optimization,2014,27:451-461.
CYMAN J,RACZEK J.Total outer-connected domination numb ers of trees[J].Discrete Applied Mathematics,2009,157:3198-3202.
DORFLING M,GODDARD W,HENNING M A,et al.Construction of trees and graphs with equal domination parameters[J].Discrete Mathematics,2006,306:2647-2654.