MAYBE
MAYBE
TRS:
 {
         mark(cons(X1, X2)) -> active(cons(mark(X1), X2)),
                  mark(0()) -> active(0()),
              mark(incr(X)) -> active(incr(mark(X))),
               mark(nats()) -> active(nats()),
               mark(odds()) -> active(odds()),
              mark(pairs()) -> active(pairs()),
                 mark(s(X)) -> active(s(mark(X))),
              mark(head(X)) -> active(head(mark(X))),
              mark(tail(X)) -> active(tail(mark(X))),
         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),
              incr(mark(X)) -> incr(X),
            incr(active(X)) -> incr(X),
  active(incr(cons(X, XS))) -> mark(cons(s(X), incr(XS))),
             active(nats()) -> mark(cons(0(), incr(nats()))),
             active(odds()) -> mark(incr(pairs())),
            active(pairs()) -> mark(cons(0(), incr(odds()))),
  active(head(cons(X, XS))) -> mark(X),
  active(tail(cons(X, XS))) -> mark(XS),
                 s(mark(X)) -> s(X),
               s(active(X)) -> s(X),
              head(mark(X)) -> head(X),
            head(active(X)) -> head(X),
              tail(mark(X)) -> tail(X),
            tail(active(X)) -> tail(X)
 }
 DUP: We consider a non-duplicating system.
  Trs:
   {
           mark(cons(X1, X2)) -> active(cons(mark(X1), X2)),
                    mark(0()) -> active(0()),
                mark(incr(X)) -> active(incr(mark(X))),
                 mark(nats()) -> active(nats()),
                 mark(odds()) -> active(odds()),
                mark(pairs()) -> active(pairs()),
                   mark(s(X)) -> active(s(mark(X))),
                mark(head(X)) -> active(head(mark(X))),
                mark(tail(X)) -> active(tail(mark(X))),
           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),
                incr(mark(X)) -> incr(X),
              incr(active(X)) -> incr(X),
    active(incr(cons(X, XS))) -> mark(cons(s(X), incr(XS))),
               active(nats()) -> mark(cons(0(), incr(nats()))),
               active(odds()) -> mark(incr(pairs())),
              active(pairs()) -> mark(cons(0(), incr(odds()))),
    active(head(cons(X, XS))) -> mark(X),
    active(tail(cons(X, XS))) -> mark(XS),
                   s(mark(X)) -> s(X),
                 s(active(X)) -> s(X),
                head(mark(X)) -> head(X),
              head(active(X)) -> head(X),
                tail(mark(X)) -> tail(X),
              tail(active(X)) -> tail(X)
   }
  Fail