让 G =(V, E ) 是一张连接的图。X ⊂ V (G) 是一个顶点集合。X 是 G 的 3-restricted 切割,如果 G-X 没被连接, G-X 的每个部件有至少三个顶点。3-restricted 连接 κ 3(G)( 在 G 的短 κ 3) ,最小的 3-restricted 的集的势 G 被切。X 被称为 κ 3-cut, 如果 | X |=κ 3 。如果 3-restricted 切割存在,图 G 是 κ 3-connected, 。让 G 是图尺寸 g ≥ 4, ξ 3(G) 是 min { d (x)+ d (y)+ d (z)− 4:xyz 是 G 的 2 路径 } 。它将在尺寸的条件下面被看那 κ 3(G)=ξ 3(G) 。
Let G = (V, E) be a connected graph. X belong to V(G) is a vertex set. X is a 3-restricted cut of G, if G- X is not connected and every component of G- X has at least three vertices. The 3-restricted connectivity κ3(G) (in short κ3) of G is the cardinality of a minimum 3-restricted cut of G. X is called κ3-cut, if |X| = κ3. A graph G is κ3-connected, if a 3-restricted cut exists. Let G be a graph girth g ≥ 4, κ3(G) is min{d(x) + d(y) + d(z) - 4 : xyz is a 2-path of G}. It will be shown that κ3(G) = ξ3(G) under the condition of girth.