transform([0], []).
transform([4], [i,v]).
transform([9], [i,x]).
transform([Digit], [i|Rest])  :-  intbtw(1, 3, Digit), 
                                  Newdigit  is  Digit - 1,
                                  transform([Newdigit], Rest).
transform([Digit], [v|Rest])  :-  intbtw(5, 8, Digit),
                                  Newdigit  is  Digit - 5,
                                  transform([Newdigit], Rest).
transform([0, Digit], Answer)  :-  transform([Digit], Answer).
transform([4, Digit], [x,l|Rest])  :-  transform([Digit], Rest).
transform([9, Digit], [x,c|Rest])  :-  transform([Digit], Rest).
transform([Digit1, Digit2], [x|Rest])  :-  intbtw(1, 3, Digit1),
                                           Newdigit  is  Digit1 - 1,
                                           transform([Newdigit, Digit2], Rest).
transform([Digit1, Digit2], [l|Rest])  :-  intbtw(5, 8, Digit1),
                                           Newdigit  is  Digit1 - 5,
                                           transform([Newdigit, Digit2], Rest).

intbtw(L, H, I) :- L =< H, !, ibt(L, H, I).
ibt(L, H, I) :- number(I), !, L =< I, I =< H.
ibt(L, H, I) :- I is L.
ibt(L, H, I) :- L1 is L+1, L1 =< H, ibt(L1, H, I).