(STRATEGY
    INNERMOST)

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