From: project2501@project2501.cor   
      
   this is a normal "intuitive" property.   
      
   a universe of all the people in the room. set A is all males. set B is all   
   children. A+B can include both males and children,  but you don't want to   
   count them twice.   
      
   H(AiB)+H(AuB)=H(A)+H(B) is rewritten more clearly..   
      
   H(A) + H(B) = union - intersection   
      
   if you draw this as plots, you'll see it clearly. if you don't subtract   
   intersection, you count the area covered by the intersection twice.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)