“…Constraint C b ≤ 1 can be shown as follows, Recall that a matrix is totally unimodular if the determinant of its any square submatrix is 0, 1 or −1. Then let us take the following submatrixC with row indices (1,3,6,12,14,15,16) and column indices (1,2,3,7,8,10,12), i.e., It turns out that the determinate ofC is −2. Thus C is not totally unimodular.…”