Estimating the score using half counting example

    Keywords: Tactics

Use half counting

Instead of counting both black and white territory, it is possible to count just one of them, using area counting. Especially in online games this is convenient, since you have to know the number of moves already played.


Asume you want to estimate the score in the following diagram. Note: It is black's turn. White has captured one stone. Black has captured two stones. 30 moves have been played.

[Diagram]
Estimate the score  

  • Select the color which looks easiest to count.
    -> White
[Diagram]
Final result?  





  • Count the empty intersections, dead opponent stones and include not yet played border stones of the selected color (normally you do not count the latter, but only the expected empty points). Dead opponent stones count for only one point in this method.
    -> Imagine it will end as in the diagram left.



[Diagram]
Count territory plus not yet played white border stones  







    -> The total number of squares is 18.










  • Add the number of board moves played/2 (round up for black, down for white). When counting for black, add the number of handicap stones minus one. Subtract this when counting for white.
    -> 18 + 30/2 = 33
  • Subtract the number of dead stones of the selected color including the already captured ones
    -> Black captured 1 stone. 33 - 1 = 32
  • Subtract the total board intersection/2. Multiply this result by 2.
    -> 32 - 81/2 = -8.5
    -> 8.5*2 = -17
  • Add or subtract komi
    -> -17 + 5.5 = -11.5

An alternative for step 3+4 is to count and add the number of living stones of the selected color currently on the board (if you don't know the number of board moves played) -- Araldo (8k)


[Diagram]
Half board comparison count  

Another quick counting method based on area counting, which is especially useful for a 9x9 board, is what I call the 'half board comparison'. To take your 'final position' as an example, if black gets the right half of the board, and white gets the left half, dividing the center line equally, the score will be even. We look how much we are away from that.

White has the squared points within "black's" half, black has the circled ones in white's. Also, black has one more point on the border than white. Black has won (according to Chinese counting) by 2x(11-3)+1=17 points (the factor 2 is because each move across the border is both one point more for the player and one less for his opponent). On 9x9 this is often a quick method of estimating the score; on larger boards it usually does not work because players have their territories divided all over the place rather than roughly dividing the board along some center line. - Andre Engels


Estimating the score using half counting example last edited by axd on November 18, 2009 - 23:08
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