(VAR x y z)
(RULES
  not(T) -> F
  not(F) -> T
  not(not(x)) -> x
  exor(x,T) -> not(x)
  exor(x,F) -> x
  exor(not(x),y) -> not(exor(x,y))
  exor(exor(x,y),z) -> exor(x,exor(y,z))
  exor(x,y) -> exor(y,x)
)
(COMMENT from the collection of \cite{AT2012})