1. Consider the directed acyclic graph (DAG) D shown below. (a) Write down the adjacency matrix A corresponding to the ordering of the vertices given by alphabetical order: a, b, c, d, e, f, g. (b)...

Help me  with b and c

Extracted text: 1. Consider the directed acyclic graph (DAG) D shown below. (a) Write down the adjacency matrix A corresponding to the ordering of the vertices given by alphabetical order: a, b, c, d, e, f, g. (b) Find all permutations of the set of vertices {a, b, c, d, e, ƒ, g} such that the asso- ciated adjacency matrix is strictly lower triangular. (c) Find the number of spanning trees rooted at vertex g.