(VAR I P X Y Z )
(RULES 
        __(__(X, Y), Z) -> __(X, __(Y, Z))
        __(X, nil) -> X
        __(nil, X) -> X
        and(tt, X) -> activate(X)
        isNePal(__(I, __(P, I))) -> tt
        activate(X) -> X
        
)