!Keyword: core of game, game theory;
Maximize  Z
   subject to
    Z - VA           <= 0 
    Z      - VB      <= 0
    Z           - VC <= 0 
        VA           >= 1.2
                  VC >= 1
        VA + VB      >= 4
        VA      + VC >= 3
             VB + VC >= 4
        VA + VB + VC <= 7
 END
