(VAR x y z)
(RULES
   +(x,0) -> x
   +(x,x) -> 0
   *(x,1) -> x
   *(x,x) -> x
   *(x,0) -> 0
   *(x,+(y,z)) -> +(*(x,y),*(x,z))
   or(x,y) -> +(*(x,y),+(x,y))
   implies(x,y) -> +(*(x,y),+(x,1))
   equivalent(x,y) -> +(+(x,y),1)
   not(x) -> +(x,1)
   +(+(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 BA on p. 262 of Hsiang 1985)