function L = graph_arc_cube ( )

%*****************************************************************************80
%
%% graph_arc_cube() sets up the arc list for the cube graph.
%
%  Discussion:
%
%    There are 8 nodes.  
%    There are 12 edges or 24 arcs.
%
%      4-----7
%     /|    /|
%    8-----3 |
%    | |   | |
%    | 5---|-2
%    |/    |/
%    1-----6
%
%  Licensing:
%
%    This code is distributed under the MIT license. 
%
%  Modified:
%
%    30 April 2026
%
%  Author:
%
%    John Burkardt
%
%  Output:
%
%    integer L(arc_num,2): the arc list.
%
  L = [ ...
    1, 5; ...
    1, 6; ...
    1, 8; ...
    2, 5; ...
    2, 6; ...
    2, 7; ...
    3, 6; ...
    3, 7; ...
    3, 8; ...
    4, 5; ...
    4, 7; ...
    4, 8; ...
    5, 1; ...
    5, 2; ...
    5, 4; ...
    6, 1; ...
    6, 2; ...
    6, 3; ...
    7, 2; ...
    7, 3; ...
    7, 4; ...
    8, 1; ...
    8, 3; ...
    8, 4 ];

  return
end
