(STRATEGY
    INNERMOST)

(VAR
    X X1 X2)
(DATATYPES
    A = µX.< a, b, f(X, X) >)
(SIGNATURES
    a__f :: [A x A] -> A
    a__b :: [] -> A
    mark :: [A] -> A)
(RULES
    a__f(X,X) -> a__f(a(),b())
    a__b() -> a()
    mark(f(X1,X2)) -> a__f(mark(X1)
                          ,X2)
    mark(b()) -> a__b()
    mark(a()) -> a()
    a__f(X1,X2) -> f(X1,X2)
    a__b() -> b())