(VAR x y z )
(RULES 
        rev(nil) -> nil
        rev(rev(x)) -> x
        rev(++(x, y)) -> ++(rev(y), rev(x))
        ++(nil, y) -> y
        ++(x, nil) -> x
        ++(.(x, y), z) -> .(x, ++(y, z))
        ++(x, ++(y, z)) -> ++(++(x, y), z)
        make(x) -> .(x, nil)
        
)