特殊用法angular vertex1.角顶点initial vertex1.初始顶点isolated vertex1.孤立顶点opposite vertex1.对顶quasi-singular vertex1.拟奇异顶点singular vertex1.奇(异)顶点terminal vertex1.悬挂点true vertex1.真顶点vertex of mirror1.镜顶vertex of switch1.辙尖理论尖端