MAYBE
MAYBE
TRS:
 {
                  length(nil()) -> 0(),
             length(cons(x, l)) -> s(length(l)),
                     lt(x, 0()) -> false(),
                  lt(0(), s(y)) -> true(),
                 lt(s(x), s(y)) -> lt(x, y),
                    head(nil()) -> undefined(),
               head(cons(x, l)) -> x,
                    tail(nil()) -> nil(),
               tail(cons(x, l)) -> l,
          rev(x, l, accu, orig) -> if(lt(x, length(orig)), x, l, accu, orig),
                     reverse(l) -> rev(0(), l, nil(), l),
  if(false(), x, l, accu, orig) -> accu,
   if(true(), x, l, accu, orig) ->
  rev(s(x), tail(l), cons(head(l), accu), orig)
 }
 DUP: We consider a duplicating system.
  Trs:
   {
                    length(nil()) -> 0(),
               length(cons(x, l)) -> s(length(l)),
                       lt(x, 0()) -> false(),
                    lt(0(), s(y)) -> true(),
                   lt(s(x), s(y)) -> lt(x, y),
                      head(nil()) -> undefined(),
                 head(cons(x, l)) -> x,
                      tail(nil()) -> nil(),
                 tail(cons(x, l)) -> l,
            rev(x, l, accu, orig) ->
    if(lt(x, length(orig)), x, l, accu, orig),
                       reverse(l) -> rev(0(), l, nil(), l),
    if(false(), x, l, accu, orig) -> accu,
     if(true(), x, l, accu, orig) ->
    rev(s(x), tail(l), cons(head(l), accu), orig)
   }
  Fail