MAYBE
MAYBE
TRS:
 {
   app(app(app(filtersub(), true()), f), app(app(cons(), y), ys)) ->
  app(app(cons(), y), app(app(filter(), f), ys)),
  app(app(app(filtersub(), false()), f), app(app(cons(), y), ys)) ->
  app(app(filter(), f), ys),
                                     app(app(filter(), f), nil()) -> nil(),
                   app(app(filter(), f), app(app(cons(), y), ys)) ->
  app(app(app(filtersub(), app(f, y)), f), app(app(cons(), y), ys))
 }
 DUP: We consider a duplicating system.
  Trs:
   {
     app(app(app(filtersub(), true()), f), app(app(cons(), y), ys)) ->
    app(app(cons(), y), app(app(filter(), f), ys)),
    app(app(app(filtersub(), false()), f), app(app(cons(), y), ys)) ->
    app(app(filter(), f), ys),
                                       app(app(filter(), f), nil()) -> nil(),
                     app(app(filter(), f), app(app(cons(), y), ys)) ->
    app(app(app(filtersub(), app(f, y)), f), app(app(cons(), y), ys))
   }
  Fail