my converter says (VAR L m n) (RULES c (A, c (n, c (0, L))) -> c (A, c (S (n), L)) c (A, c (0, c (S (m), L))) -> c (A, c (S (0), c (m, L))) c (A, c (S (n), c (S (m), L))) -> c (A, c (n, c (S (m), c (m, L)))))