4

So I have another question about counting territory. 

$$ ---------------------
$$ | . . . . . O w w w |
$$ | . . . . . O w w w |
$$ | . . . . . . O O O |
$$ | . . . . . . . . . |
$$ | . . . . . . . . . |
$$ | . . . . . . . . . |
$$ | . . . . . . . . . |
$$ | . . . . . . . . . |
$$ | . . . . . . . . . |
$$ ---------------------

In this position, all of the squares marked "w" would be whites territory. I have two questions about this. First off, why would none of the other open spaces on the board count for white? In a way, he is surrounding them. And secondly, If black played like so:

$$ ---------------------
$$ | . . . . . O w X w |
$$ | . . . . . O w w w |
$$ | . . . . . . O O O |
$$ | . . . . . . . . . |
$$ | . . . . . . . . . |
$$ | . . . . . . . . . |
$$ | . . . . . . . . . |
$$ | . . . . . . . . . |
$$ | . . . . . . . . . |
$$ ---------------------

Would this automatically negate all of the territory that white is surrounding, simply because it interrupts the border? If so, wouldn't this be an extremely valuable move, because in order for white to take that piece and reclaim all of that territory, he would have to play like this:

$$ ---------------------
$$ | . . . . . O O w O |
$$ | . . . . . O w O w |
$$ | . . . . . . O O O |
$$ | . . . . . . . . . |
$$ | . . . . . . . . . |
$$ | . . . . . . . . . |
$$ | . . . . . . . . . |
$$ | . . . . . . . . . |
$$ | . . . . . . . . . |
$$ ---------------------

Which leaves him with three less points that in the beginning. Any answers are appreciated. Thanks!

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3 Answers 3

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5

Firstly, note that it doesn't matter who owns what territory until the game is over, and none of these are realistic ending scenarios. However, let's assume the game did end with each of your first two boards.

On the first board, the entire board would be considered White's territory.

On the second, among two good players, Black and White would agree that Black's stone is dead. White would then automatically capture Black's stone before scoring.

What happens if Black refuses to agree his stone is toast? You do indeed have to play it out and end up with board 3. However, White is not penalized for playing those extra stones:

  • If you are playing with area scoring, stones on the board are a point each just like territory controlled, so board 3 scores just as well as board 1 for White.

  • If you are playing with territory scoring, all play after the game has ended is considered purely hypothetical - it exists solely to resolve the dispute over which stones are still alive. White proves her claim that Black's stone is dead by playing until board 3, but then the game reverts back to board 2 (and White auto-captures Black's dead stone) before scoring.

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5
  • A source
    – Benjamin Cosman
    Feb 28, 2017 at 23:42
  • Okay! Thank you. That was very informative. Just to clear things up, however, how could black make it so that white did not control any of the lower left territory? Would he simply have to place a stone or formation of stones along any of the edges, cutting whites border? Or would you have to actually take out one of whites stones to break the line formation?
    – SpiralStudios
    Feb 28, 2017 at 23:43
  • Just as a note, I am extremely new to the game of Go... I understand the basic rules of play, but scoring is still extremely confusing to me, and their are a lot of aspects of counting territory that I don't understand.
    – SpiralStudios
    Feb 28, 2017 at 23:44
  • At the end of the game, once all dead stones are auto-captured (either because both players agree they're dead or it is proven in hypothetical after-play), an intersection is part of your territory only if there is no way to "walk" from there through open intersections to reach an enemy stone. So if Black has a single stone that is considered alive anywhere in the lower left (not just on the edge) at the end of the game, then none of the lower left belongs to either player.
    – Benjamin Cosman
    Feb 28, 2017 at 23:49
  • My recommendation (though I know there is disagreement on this point) is to use area scoring if you're confused - that way you can just play out any sections you're not sure are completely settled (and in doing so, get a better idea of what is in fact alive or dead).
    – Benjamin Cosman
    Feb 28, 2017 at 23:52
4

The answers about counting by Benjamin Cosman and TimK are up to the point, but there is more in this position. Imagine, that black walls in the white position like this

$$ ---------------------
$$ | . . . . X O . a . |
$$ | . . . . X O . . . |
$$ | . . . . X O O O O |
$$ | . . . . X X X X X |
$$ | . . . . . . . . . |
$$ | . . . . . . . . . |
$$ | . . . . . . . . . |
$$ | . . . . . . . . . |
$$ | . . . . . . . . . |
$$ ---------------------

Than a black move on a becomes an effective move against the white group:

$$ ---------------------
$$ | . . . . X O 3 1 4 |
$$ | . . . . X O . 2 5 |
$$ | . . . . X O O O O |
$$ | . . . . X X X X X |
$$ | . . . . . . . . . |
$$ | . . . . . . . . . |
$$ | . . . . . . . . . |
$$ | . . . . . . . . . |
$$ | . . . . . . . . . |
$$ ---------------------

and the white group is killed in a position known as "bent four in the corner". In order to live unconditionally, white needs to take the point a or to secure a second eye on the outside of her group.

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3
  • 2
    I think this is an important part of the root of the question. @SpiralStudios I would suggest that you take a look at some "life and death" concepts in go. It will give you insight into the characteristics of groups that are settled. You could try to start at Sensei's Library.
    – BBS
    Mar 1, 2017 at 13:34
  • 1
    Thanks! I think that the life and death concepts were really the root of my misunderstanding. Once I got that, it really helped my understanding.
    – SpiralStudios
    Mar 1, 2017 at 19:11
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    Actually, this is the wrong way to kill the group. That's a ko, not bent-four in the corner. If Black plays the other middle point, and then extends to the right, the group is unconditionally dead.
    – TimK
    Mar 6, 2017 at 20:00
1

When there are stones in a territory like that at the end of the game, as long as both players agree on their status, then they can be counted as dead. Otherwise there are ways of resolving the dispute that don't affect the score so that your idea of White losing points can be avoided. In general playing stones that can't live in a territory either loses a point or doesn't change the score. If White can afford to ignore the move, then she winds up with one extra prisoner at the end of the game, and if not, then White answers inside the territory, and has gained a prisoner and also covered a point so it's a wash.

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