> I want to thank all contributors to my first post on Lotto simulation for their valuable input.
> As a conclusion I decided to use the containers.vectors package. Here is my solution. Please
> feel free to comment on any aspect.

Looks OK, in principle. Some of your identifiers may be too short to 
understand what is going on (e.g., tz, iz), and, when communicating Ada 
source code, you should lean to capitalize identifiers (Tz or TZ, but not 
tz), ect ...

Also, it is a little surprising that you don't output your results.

However, my main criticism would be that your usage of Vectors is overkill 
for the problem at hand. Here is a solution using a single array, instead 
of two containers.

with Ada.Numerics.Discrete_Random, Ada.Text_IO;

procedure Ziehung2 is
    subtype Index is Integer range 1 .. 49;
    Ball: array(Index) of Index;
begin
    -- intialize Ball
    for I in Index loop
       Ball(I) := I;
    end loop;

    -- draw six numbers and print them
    for I in 0 .. 5 loop
       -- invariant: Ball(1 .. Index'Last-I) hold the balls not yet drawn
       --    Ball(Index'Last-I+1 .. Index'Last) hold the balls drawn so far
       declare
 	 subtype Z is Index range 1 .. Index'Last-I;
 	 package RND is new Ada.Numerics.Discrete_Random(Z);
 	 Gen: RND.Generator;
 	 Drawn, Tmp: Index;
       begin
 	 RND.Reset(Gen);
 	 Drawn := Rnd.Random(Gen); -- Drawn := random index
 	 Ada.Text_IO.Put(Index'Image(Ball(Drawn))); -- print Ball(Drawn)

 	 -- move Ball(Drawn) to the end of Ball(1 .. Index'Last-I)
 	 -- more precisely, swap Ball(Index'Last-I) and Ball(Drawn)
 	 Tmp := Ball(Index'Last-I);
 	 Ball(Index'Last-I) := Ball(Drawn);
 	 Ball(Drawn) := Tmp;
       end;
    end loop;
end Ziehung2


------  I  love  the  taste  of  Cryptanalysis  in  the morning!  ------
     <http://www.uni-weimar.de/cms/medien/mediensicherheit/home.html>
--Stefan.Lucks (at) uni-weimar.de, Bauhaus-Universität Weimar, Germany--