On Dec 26, 4:38 am, Ehsan  wrote:   
   > Hi   
   > I want to solve to rubik cube by A* search, I found some heuristics ,   
   > it's wondering if anyone could help me to find more better heuristics   
   > (reference to a paper or a web page)? if you know any admissible   
   > heuristic i will happy if you share it with me.   
   >   
   > thanx   
   > Ehsan   
   >   
      
   You may count the number of squares by colors for all the 6 sides.   
      
   Let say we have colors R G B W Y C   
      
   you should have 6 histograms like the one below   
      
   side-1:   
      
   R 1   
   G 0   
   B 5   
   W 0   
   Y 0   
   C 2   
      
   Then we calculate the max for each side. In our example it is B (blue)   
   with value 5.   
      
   Then we subtract this value from 9. So the heuristic for this side ise   
   4. (*) The zero heuristic is the best.   
      
   Then we sum these heuristics for all sides.   
      
   (*) You may also add squares of the counts for the other colors (other   
   than the max [B]) to enchance this heuristic.   
      
   [ comp.ai is moderated ... your article may take a while to appear. ]   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)