x -x 2/3 a
x 2*x 1/3 a
-2*x -x 0 a
x -x 1/6 b
x 2*x 5/6 b
-2*x -x 1/2 b
x y z c
-y x-y z+2/3 c
-x+y -x z+1/3 c
-y -x -z+1/3 c
-x+y y -z+2/3 c
x x-y -z c