Define graph matrix and connection matrix.     

Graph matrix: A graph matrix is a square matrix whose size (i.e., number of rows and columns) is equivalent to the number of nodes on the flow graph.  Every row and column corresponds to an identified node, and matrix entries correspond to connections (an edge) among nodes

Connection matrix:  In connection matrix, every letter has been replaced with a 1, indicating that a connection exists (zeros have been excluded for clarity).