设G=(V,E)是一个图。集合S真包含V称为一个k-分支限制控制集.如果S是一个限制控制集且G[S]最多有k个分支。G的k-分支限制控制数是G的最小k-分支限制控制集的基数,记作γr^k(G)。证明了若树T有n个顶点,则γr^k(T)≥max{[n+2/3],n-2(k-1)},而且刻画了可以达到这个下界的树。
Let G = ( V, E) be a graph. A k-component restrained dominating set is a subset S lohtain in V which S is a restrained dominating set and G[ S] has at most k components. The k-component restrained domination number of G, denoted by γr^k (G), is the smallest cardinality of a k-component restrained dominating set of G. It is proved that if T is a tree of order n, then γr^k(T)≥max{[n+2/3],n-2(k-1)}.Moreover, the extremal trees T of order n achieving this lower bound are characterized.