| 1: | a__2nd(cons(X,cons(Y,Z))) | → mark(Y) | |
| 2: | a__from(X) | → cons(mark(X),from(s(X))) | |
| 3: | mark(2nd(X)) | → a__2nd(mark(X)) | |
| 4: | mark(from(X)) | → a__from(mark(X)) | |
| 5: | mark(cons(X1,X2)) | → cons(mark(X1),X2) | |
| 6: | mark(s(X)) | → s(mark(X)) | |
| 7: | a__2nd(X) | → 2nd(X) | |
| 8: | a__from(X) | → from(X) | |
| 9: | A__2ND(cons(X,cons(Y,Z))) | → MARK(Y) | |
| 10: | A__FROM(X) | → MARK(X) | |
| 11: | MARK(2nd(X)) | → A__2ND(mark(X)) | |
| 12: | MARK(2nd(X)) | → MARK(X) | |
| 13: | MARK(from(X)) | → A__FROM(mark(X)) | |
| 14: | MARK(from(X)) | → MARK(X) | |
| 15: | MARK(cons(X1,X2)) | → MARK(X1) | |
| 16: | MARK(s(X)) | → MARK(X) | |