(VAR X Y Z X1) (RULES 2nd(cons1(X,cons(Y,Z))) -> Y 2nd(cons(X,X1)) -> 2nd(cons1(X,activate(X1))) from(X) -> cons(X,n__from(s(X))) from(X) -> n__from(X) activate(n__from(X)) -> from(X) activate(X) -> X )