mat( ( -1, 0, 0,   0, 0, 0, 1,   0, 0, 1),
     (  1,-1, 0,   0, 0, 0, 0,   0, 1, 0),
     (  0, 1,-1,   0, 0, 0, 0,   0, 0, 0),
     (  0, 0, 1,  -1, 0, 0, 0,   0, 0, 0),
     (  0, 0, 0,   1,-1, 0, 0,   0, 0, 0),
     (  0, 0, 0,   0, 1,-1, 0,   0, 0, 0),
     (  0, 0, 0,   0, 0, 1,-1,  -1, 0, 0),
     (  0, 0, 0,   0, 0, 0, 0,   1,-1,-1),
     ( -1, 0, 0,-1/2, 0, 0, 0,-1/2, 0, 0),
     (  0,-1, 0,   0,-1, 0, 0,   0, 0,-1),
     (  0, 0, 0,   0, 0, 1, 0,   0, 0, 0),
     (  0, 0, 0,   0, 0, 0, 0,   0, 0, 1),
     (  0, 0, 0,   0, 0, 0, 1,   0, 1, 0),
     (  1, 0, 0, 1/2, 0, 0, 0, 1/2, 0, 0),
     (  0, 0, 0,   0, 0, 0, 0,   0, 0, 0 ) )