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