4. Suppose we are given an unweighted, directed graph G with n vertices (labelled 1 to n), and let M be the n x n adjacency matrix for G (that is, M(i,j) 1 if directed edge (i, j) is in G and 0 otherwise). a. Let the product of M with itself (M2) be defined, for 1 sijsn, as follows: where "" is the Boolean and operator and"+"is the Boolean or operator. Given this definition what does M2(i,j)- 1 imply about vertices i and j? What if M2(i,j) 0? b. Suppose M4 is the product of M2 with itself. What do the entries of M4 signify? What about M for any 1 s ks n