UNB/ CS/ David Bremner/ teaching/ cs6375/ examples/ bipartite
    1  1  0  0  1  1  1  0 
    1  0  1  1  0  1  0  1

    x[1,A].val = 0.5
    x[1,B].val = 0.5
    x[2,A].val = 0.5
    x[2,D].val = 0.5
    x[3,C].val = 1.0
    x[4,B].val = 0.5
    x[4,D].val = 0.5