Problem:
 sel(s(X),cons(Y,Z)) -> sel(X,Z)
 sel(0(),cons(X,Z)) -> X
 first(0(),Z) -> nil()
 first(s(X),cons(Y,Z)) -> cons(Y,first(X,Z))
 from(X) -> cons(X,from(s(X)))
 sel1(s(X),cons(Y,Z)) -> sel1(X,Z)
 sel1(0(),cons(X,Z)) -> quote(X)
 first1(0(),Z) -> nil1()
 first1(s(X),cons(Y,Z)) -> cons1(quote(Y),first1(X,Z))
 quote(0()) -> 01()
 quote1(cons(X,Z)) -> cons1(quote(X),quote1(Z))
 quote1(nil()) -> nil1()
 quote(s(X)) -> s1(quote(X))
 quote(sel(X,Z)) -> sel1(X,Z)
 quote1(first(X,Z)) -> first1(X,Z)
 unquote(01()) -> 0()
 unquote(s1(X)) -> s(unquote(X))
 unquote1(nil1()) -> nil()
 unquote1(cons1(X,Z)) -> fcons(unquote(X),unquote1(Z))
 fcons(X,Z) -> cons(X,Z)

Proof:
 Containment Processor: loop length: 1
                        terms:
                         from(X)
                        context: cons(X,[])
                        substitution:
                         X -> s(X)
  Qed