(VAR x y z)
(RULES
  +(+(x,y),z) -> +(x,+(y,z))
  +(x,y) -> +(y,x)
  *(*(x,y),z) -> *(x,*(y,z))
  *(x,y) -> *(y,x)
  *(+(x,y),z) -> +(*(x,z),*(y,z))
)
(COMMENT from the collection of \cite{AT2012})