(STRATEGY
    INNERMOST)

(VAR
    x y)
(DATATYPES
    A = µX.< s(X), 0 >)
(SIGNATURES
    plus :: [A x A] -> A
    ack :: [A x A] -> A)
(RULES
    plus(s(s(x)),y) -> s(plus(x
                             ,s(y)))
    plus(x,s(s(y))) -> s(plus(s(x)
                             ,y))
    plus(s(0()),y) -> s(y)
    plus(0(),y) -> y
    ack(0(),y) -> s(y)
    ack(s(x),0()) -> ack(x,s(0()))
    ack(s(x),s(y)) -> ack(x
                         ,plus(y,ack(s(x),y))))