MAYBE
MAYBE
TRS:
 {
  app(app(app(rec(), f), x), app(s(), y)) ->
  app(app(f, app(s(), y)), app(app(app(rec(), f), x), y)),
          app(app(app(rec(), f), x), 0()) -> x
 }
 DUP: We consider a duplicating system.
  Trs:
   {
    app(app(app(rec(), f), x), app(s(), y)) ->
    app(app(f, app(s(), y)), app(app(app(rec(), f), x), y)),
            app(app(app(rec(), f), x), 0()) -> x
   }
  Fail