0 ①2 A edge 0101 1010 301 010 Aedge=10 1 000 2 The adjacency matrix of non-directional graph is symmetrical The adjacency matrix of directional graph is not always symmetrical◼ The adjacency matrix of non-directional graph is symmetrical ◼ The adjacency matrix of directional graph is not always symmetrical 0 1 2 3           = 1 0 1 0 0 1 0 1 1 0 1 0 0 1 0 1 A.edge 0 1 2         = 0 0 0 1 0 1 0 1 0 A.edge