Chv’atal定理的构造法直接证明

Unialteral connectedness and the connectedness of subsets

本文给出Ｃｈｖ’ａｔａｌ定理的逆否形式，并用构造法给出简捷的直接证明．

In this paper the definition of the connectedness of subsets is first brought in for sets of vartices of the simple diagram G= (V, E), then it is pointed out that the diagram is unilaterally connected if and only if it is characterized ty the connectedness of subsets. Also, some important properties of them (the connectedness of subsets) are described.