YES TRS: active(first(0(),X)) -> mark(nil()) active(first(s(X),cons(Y,Z))) -> mark(cons(Y,first(X,Z))) active(from(X)) -> mark(cons(X,from(s(X)))) mark(first(X1,X2)) -> active(first(mark(X1),mark(X2))) mark(0()) -> active(0()) mark(nil()) -> active(nil()) mark(s(X)) -> active(s(mark(X))) mark(cons(X1,X2)) -> active(cons(mark(X1),X2)) mark(from(X)) -> active(from(mark(X))) first(mark(X1),X2) -> first(X1,X2) first(X1,mark(X2)) -> first(X1,X2) first(active(X1),X2) -> first(X1,X2) first(X1,active(X2)) -> first(X1,X2) s(mark(X)) -> s(X) s(active(X)) -> s(X) cons(mark(X1),X2) -> cons(X1,X2) cons(X1,mark(X2)) -> cons(X1,X2) cons(active(X1),X2) -> cons(X1,X2) cons(X1,active(X2)) -> cons(X1,X2) from(mark(X)) -> from(X) from(active(X)) -> from(X) linear polynomial interpretations on N: active_A(x1) = x1 active#_A(x1) = x1 + 2 first_A(x1,x2) = x1 + x2 + 4 first#_A(x1,x2) = 7 0_A = 3 0#_A = 0 mark_A(x1) = x1 mark#_A(x1) = x1 + 4 nil_A = 4 nil#_A = 1 s_A(x1) = x1 + 1 s#_A(x1) = 0 cons_A(x1,x2) = x1 + 2 cons#_A(x1,x2) = 5 from_A(x1) = x1 + 5 from#_A(x1) = 1 precedence: active > mark > first = from > nil = s = cons > 0