Problem: tail(cons(X)) -> XS pairNs() -> cons(0()) oddNs() -> incr(pairNs()) incr(cons(X)) -> cons(s(X)) take(0(),XS) -> nil() take(s(N),cons(X)) -> cons(X) zip(nil(),XS) -> nil() zip(X,nil()) -> nil() zip(cons(X),cons(Y)) -> cons(pair(X,Y)) repItems(nil()) -> nil() repItems(cons(X)) -> cons(X) Proof: Fresh Variable Processor: loop length: 1 terms: tail(cons(X)) context: [] substitution: XS -> tail(cons(X)) Qed