(VAR f x xs y )
(RULES 
        app(app(map, f), nil) -> nil
        app(app(map, f), app(app(cons, x), xs)) -> app(app(cons, app(f, x)), app(app(map, f), xs))
        app(app(minus, x), 0) -> x
        app(app(minus, app(s, x)), app(s, y)) -> app(app(minus, app(p, app(s, x))), app(p, app(s, y)))
        app(p, app(s, x)) -> x
        app(app(div, 0), app(s, y)) -> 0
        app(app(div, app(s, x)), app(s, y)) -> app(s, app(app(div, app(app(minus, x), app(id, y))), app(s, y)))
        app(id, x) -> x
        app(id, x) -> app(s, app(s, app(s, x)))
        app(id, app(p, x)) -> app(id, app(s, app(id, x)))
        
)