/* ************************************************ */
     /*                                                  */
     /*   delete_nth1/3                                  */
     /*      Arg 1:  Counter: integer                    */
     /*      Arg 2:  List                                */
     /*      Arg 3:  List                                */
     /*   Summary: calls delete_nth/4.                   */
     /*   Author: P J Hancox                             */
     /*   Date:   22 October 1994                        */
     /*                                                  */
     /* ************************************************ */

     delete_nth1(Pos, List1, List2) :-
          delete_nth1(1, Pos, List1, List2).

     /* ************************************************ */
     /*                                                  */
     /*   delete_nth1/4                                  */
     /*      Arg 1:  Counter: integer                    */
     /*      Arg 2:  Position: integer                   */
     /*      Arg 3:  List with element                   */
     /*      Arg 4:  List without element                */
     /*   Summary: true if Arg 3 is Arg 4 without Elem   */
     /*            at Pos.                               */
     /*   Author: P J Hancox                             */
     /*   Date:   22 October 1994                        */
     /*                                                  */
     /* ************************************************ */

     % 1 terminating condition
     delete_nth1(Pos, Pos, [Elem|Tail], Tail).
     % 2 recursive
     delete_nth1(Cnt, Pos, [Head|Tail1], [Head|Tail2]) :-
          Cnt1 is Cnt + 1,
          delete_nth1(Cnt1, Pos, Tail1, Tail2).