(VAR w x y z)
(RULES
   +(x,0) -> x
   -(0) -> 0
   -(-(x)) -> x
   -(+(x,y)) -> +(-(x),-(y))
   +(x,-(x)) -> 0
   +(+(x,-(x)),y) -> y
   *(x,0) -> 0
   *(x,1) -> x
   *(x,-(y)) -> -(*(x,y))
   *(*(x,-(y)),z) -> *(-(*(x,y)),z)
   *(x,+(y,z)) -> +(*(x,y),*(x,z))
   *(*(x,+(y,z)),w) -> +(*(*(x,y),w),*(*(x,z),w))
   +(+(x,y),z) -> +(x,+(y,z))
   +(x,+(y,z)) -> +(+(x,y),z)
   +(x,y) -> +(y,x)
   *(*(x,y),z) -> *(x,*(y,z))
   *(x,*(y,z)) -> *(*(x,y),z)
   *(x,y) -> *(y,x)
)
(COMMENT Example 3.27 of Bachmair 1991)