(GOAL COMPLEXITY)
(STARTTERM CONSTRUCTORBASED)
(VAR x xs y )
(STRATEGY INNERMOST)
(RULES 
        sub(0, 0) -> 0
        sub(s(x), 0) -> s(x)
        sub(0, s(x)) -> 0
        sub(s(x), s(y)) -> sub(x, y)
        zero(nil) -> zero2(0, nil)
        zero(cons(x, xs)) -> zero2(sub(x, x), cons(x, xs))
        zero2(0, nil) -> nil
        zero2(0, cons(x, xs)) -> cons(sub(x, x), zero(xs))
        zero2(s(y), nil) -> zero(nil)
        zero2(s(y), cons(x, xs)) -> zero(cons(x, xs))
        
)