MAYBE MAYBE TRS: { 2nd(cons1(X, cons(Y, Z))) -> Y, 2nd(cons(X, X1)) -> 2nd(cons1(X, X1)), from(X) -> cons(X, from(s(X))) } DUP: We consider a duplicating system. Trs: { 2nd(cons1(X, cons(Y, Z))) -> Y, 2nd(cons(X, X1)) -> 2nd(cons1(X, X1)), from(X) -> cons(X, from(s(X))) } Fail