MAYBE
MAYBE
TRS:
 {
             mark(cons(X1, X2)) -> active(cons(mark(X1), X2)),
                     mark(f(X)) -> active(f(mark(X))),
                     mark(g(X)) -> active(g(mark(X))),
                     mark(s(X)) -> active(s(mark(X))),
                      mark(0()) -> active(0()),
              mark(sel(X1, X2)) -> active(sel(mark(X1), mark(X2))),
             cons(X1, mark(X2)) -> cons(X1, X2),
           cons(X1, active(X2)) -> cons(X1, X2),
             cons(mark(X1), X2) -> cons(X1, X2),
           cons(active(X1), X2) -> cons(X1, X2),
                     f(mark(X)) -> f(X),
                   f(active(X)) -> f(X),
                     g(mark(X)) -> g(X),
                   g(active(X)) -> g(X),
                   active(f(X)) -> mark(cons(X, f(g(X)))),
                active(g(s(X))) -> mark(s(s(g(X)))),
                 active(g(0())) -> mark(s(0())),
  active(sel(s(X), cons(Y, Z))) -> mark(sel(X, Z)),
   active(sel(0(), cons(X, Y))) -> mark(X),
                     s(mark(X)) -> s(X),
                   s(active(X)) -> s(X),
              sel(X1, mark(X2)) -> sel(X1, X2),
            sel(X1, active(X2)) -> sel(X1, X2),
              sel(mark(X1), X2) -> sel(X1, X2),
            sel(active(X1), X2) -> sel(X1, X2)
 }
 DUP: We consider a duplicating system.
  Trs:
   {
               mark(cons(X1, X2)) -> active(cons(mark(X1), X2)),
                       mark(f(X)) -> active(f(mark(X))),
                       mark(g(X)) -> active(g(mark(X))),
                       mark(s(X)) -> active(s(mark(X))),
                        mark(0()) -> active(0()),
                mark(sel(X1, X2)) -> active(sel(mark(X1), mark(X2))),
               cons(X1, mark(X2)) -> cons(X1, X2),
             cons(X1, active(X2)) -> cons(X1, X2),
               cons(mark(X1), X2) -> cons(X1, X2),
             cons(active(X1), X2) -> cons(X1, X2),
                       f(mark(X)) -> f(X),
                     f(active(X)) -> f(X),
                       g(mark(X)) -> g(X),
                     g(active(X)) -> g(X),
                     active(f(X)) -> mark(cons(X, f(g(X)))),
                  active(g(s(X))) -> mark(s(s(g(X)))),
                   active(g(0())) -> mark(s(0())),
    active(sel(s(X), cons(Y, Z))) -> mark(sel(X, Z)),
     active(sel(0(), cons(X, Y))) -> mark(X),
                       s(mark(X)) -> s(X),
                     s(active(X)) -> s(X),
                sel(X1, mark(X2)) -> sel(X1, X2),
              sel(X1, active(X2)) -> sel(X1, X2),
                sel(mark(X1), X2) -> sel(X1, X2),
              sel(active(X1), X2) -> sel(X1, X2)
   }
  Fail