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Score that Game!
http://www.lifein19x19.com/viewtopic.php?f=15&t=9098		 Page 1 of 1
Author:  Bill Spight [ Wed Sep 18, 2013 8:36 am ]
Post subject:  Score that Game!
In Korschelt's day game records were often published that stopped even before the dame stage. Korschelt remarked that good players could work out correct play to the end. Given the recent threads on counting and on end of game questions, I thought it might be interesting to back up a game several moves to a point where it should still be not too difficult to figure out the final score, with best play by both sides. :) I ask for the score rather than the count because the count could well be fractional.

Click Here To Show Diagram Code
[go]$$W White to play
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . O X X . . |
$$ | . . . . . . . . . . . . . O . O X X . |
$$ | . O . . O O O O O O . O O X O O O X . |
$$ | O . O O X O X . X O X . X X O , . . . |
$$ | . O X X X X . X X X X . X . O X X . . |
$$ | O X . O X . X X O . . . . O O X . . . |
$$ | . X X X O X . O X X X . . O X O . . . |
$$ | X O O O O X . O O O . O O X X X . . . |
$$ | O . O . . O O . . . . O X . . . X . . |
$$ | . O . , . . . . . , O X X X X , . . . |
$$ | . . . O O . . O . O O X O X O X X . . |
$$ | . X O X . O . . O X O X O O O O X X . |
$$ | . O O X . X X X X B O . . . . . X . X |
$$ | . O X X O O O X . X X . . O O O O X X |
$$ | . . O O X X X . . . X O O . X . . O X |
$$ | . O . O X O . . . , O X X . X O . O X |
$$ | . O O X . X O X . . X . . X O O . O O |
$$ | X O X . X X . . . . . X X O . O . . . |
$$ | . X . . . . . . . . . . O . O . . . . |
$$ ---------------------------------------[/go]


Black has captured 3 White stones, White has captured 6 Black stones. No komi. :bc: is the last play.

What is the final score with best play?

Enjoy!
Author:  Dusk Eagle [ Wed Sep 18, 2013 12:10 pm ]
Post subject:  Re: Score that Game!
The best I can get is an estimate of W+1 (Black 80, White 81). I wasn't confident in absolute best play though, so I relied on a couple of estimates to aid my count.
Author:  mitsun [ Wed Sep 18, 2013 3:53 pm ]
Post subject:  Re: Score that Game!
First fill in some obvious sente plays. I don't think either side can avoid these.

Click Here To Show Diagram Code
[go]$$
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . O X X . . |
$$ | . . . . . . . . . . O . . O . O X X . |
$$ | . O . . O O O O O O X O O X O O O X . |
$$ | O . O O X O X . X O X . X X O , W B . |
$$ | . O X X X X . X X X X . X . O X X . . |
$$ | O X B . X . X X O . . . . O O X . . . |
$$ | W X X X O X . O X X X . . O X O . . . |
$$ | . O O O O X . O O O . O O X X X . . . |
$$ | O . O . . O O . . . . O X . . . X . . |
$$ | . O . , . . . . . , O X X X X , . . . |
$$ | . . . O O . . O . O O X O X O X X . . |
$$ | . X O X W O . . O X O X O O O O X X . |
$$ | . O O X B X X X X X O . . . . . X . X |
$$ | . O X X . . . X . X X . . O O O O X X |
$$ | . . O O X X X . . . X O O . X W . O X |
$$ | . O . O X O . . . , O X X B X O . O X |
$$ | . O O X . X O X . . X . . X O O . O O |
$$ | X O X . X X . . . . . X X O . O . . . |
$$ | . X . . . . . . . . . . O . O . . . . |
$$ ---------------------------------------[/go]


Next I imagine W will take the 2+ gote play on top, which earns him the marked follow-up.

Click Here To Show Diagram Code
[go]$$
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . O X X . . |
$$ | . . . . . . . . . . O . . O . O X X . |
$$ | . O . . O O O O O O X O O X O O O X . |
$$ | O . O O X O X . X O X . X X O , O X . |
$$ | . O X X X X . X X X X . X . O X X . . |
$$ | O X X . X . X X . B W W . O O X . . . |
$$ | O X X X O X . O X X X . . O X O . . . |
$$ | . O O O O X . O O O . O O X X X . . . |
$$ | O . O . . O O . . . . O X . . . X . . |
$$ | . O . , . . . . . , O X X X X , . . . |
$$ | . . . O O . . O . O O X O X O X X . . |
$$ | . X O X O O . . O X O X O O O O X X . |
$$ | . O O X X X X X X X O . . . . . X . X |
$$ | . O X X . . . X . X X . . O O O O X X |
$$ | . . O O X X X . . . X O O . X O . O X |
$$ | . O . O X O . . . , O X X X X O . O X |
$$ | . O O X . X O X . . X . . X O O . O O |
$$ | X O X . X X . . . . . X X O . O . . . |
$$ | . X . . . . . . . . . . O . O . . . . |
$$ ---------------------------------------[/go]


Now there are two plays worth 2 points gote, so let's give one to each side.

Click Here To Show Diagram Code
[go]$$
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . O X X . . |
$$ | . . . . . . . . . . O . . O . O X X . |
$$ | . O . . O O O O O O X O O X O O O X . |
$$ | O . O O X O X . X O X . X X O , O X . |
$$ | . O X X X X . X X X X . X . O X X . . |
$$ | O X X . X . X X . X O O . O O X . . . |
$$ | O X X X O X . O X X X . B O X O . . . |
$$ | . O O O O X . O O O . O O X X X . . . |
$$ | O . O . . O O . . . . O X . . . X . . |
$$ | . O . , . . . . . , O X X X X , . . . |
$$ | . . . O O . . O . O O X O X O X X . . |
$$ | . X O X O O . . O X O X O O O O X X . |
$$ | . O O X X X X X X X O W . . . . X . X |
$$ | . O X X . . . X . X X . . O O O O X X |
$$ | . . O O X X X . . . X O O . X O . O X |
$$ | . O . O X O . . . , O X X X X O . O X |
$$ | . O O X . X O X . . X . . X O O . O O |
$$ | X O X . X X . . . . . X X O . O . . . |
$$ | . X . . . . . . . . . . O . O . . . . |
$$ ---------------------------------------[/go]


Now give B all his remaining remaining sente plays and do the same for W.
Finally, fill in the last few points with a simple finish avoiding ko fights.

Click Here To Show Diagram Code
[go]$$W
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . O X X . . |
$$ | . . . . . . . . . . O . . O . O X X . |
$$ | . O . . O O O O O O X O O X O O O X . |
$$ | O . O O X O X B X O X . X X O , O X . |
$$ | . O X X X X . X X X X . X . O X X . . |
$$ | O X X . X . X X . X O O . O O X . . . |
$$ | O X X X O X W O X X X . X O X O . . . |
$$ | . O O O O X . O O O B O O X X X . . . |
$$ | O . O . . O O . . . W O X . . . X . . |
$$ | . O . , . . . . . , O X X X X , . . . |
$$ | . . . O O . W O W O O X O X O X X . . |
$$ | . X O X O O B B O X O X O O O O X X . |
$$ | . O O X X X X X X X O O . . W B X . X |
$$ | . O X X . . . X . X X B W O O O O X X |
$$ | . . O O X X X . . . X O O . X O . O X |
$$ | . O . O X O . . . , O X X X X O . O X |
$$ | W O O X . X O X . . X . . X O O . O O |
$$ | X O X . X X . . . . . X X O . O . . . |
$$ | B X B . . . . . . . . B O W O . . . . |
$$ ---------------------------------------[/go]


If I counted the end result correctly, the score is even. I gave W nothing for having the move in the initial position, and I gave B almost all of the last sente plays, so I think W can win by taking a reverse-sente play somewhere in this sequence. I predict W wins by 1 point.
Author:  Bill Spight [ Fri Sep 20, 2013 8:29 am ]
Post subject:  Re: Score that Game!
The solvers were correct. :) Maybe this was too easy?

But they were dan players. Maybe it was too hard?

(I thought that this was around 3 kyu level.)

As the game is at the level of plays that gain 1 pt. and ko is not a factor, it is scorable to within 1 pt. White is ahead by 3/4 pt., which with the move he can "round up" to a 1 pt. win.

The center top region is tricky. I believe that it is ambiguous, with Black getting the last 1 pt. play there.

Here is an sgf of the game, with some comments starting at move 201. :)
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