4

I'm a bit confused by the rules of surrounding.

For example this board:

$$ +------------------+
$$ |.......OX.........|
$$ |.....XOOX.........|
$$ |....XOOX..........|
$$ |...,XOX..,....,...|
$$ |...XOOX...........|
$$ |...XOX............|
$$ |..XOOX............|
$$ |.XOO..............|
$$ |XOO.X.............|
$$ |XOOX.....,....,...|
$$ |OOX...............|
$$ |OXX...............|
$$ |XX................|
$$ |..................|
$$ |..................|
$$ |...,.....,....,...|
$$ |..................|
$$ |..................|
$$ |..................|
$$ +------------------+

What fields are now mine (assuming I'm white)?

In almost every example I found it was like this (X = captured) :

$$ +------------------+
$$ |???????OX.........|
$$ |?????ZOOX.........|
$$ |????ZOOX..........|
$$ |????ZOX..,....,...|
$$ |???ZOOX...........|
$$ |???ZOX............|
$$ |??ZOOX............|
$$ |?ZOO..............|
$$ |ZOO.X.............|
$$ |XOOX.....,....,...|
$$ |OOX...............|
$$ |OXX...............|
$$ |XX................|
$$ |..................|
$$ |..................|
$$ |...,.....,....,...|
$$ |..................|
$$ |..................|
$$ |..................|
$$ +------------------+

Why can't it be like this?

$$ +------------------+
$$ |.......OZ?????????|
$$ |.....XOOZ?????????|
$$ |....XOOZ??????????|
$$ |...,XOZ???????????|
$$ |...XOOZ???????????|
$$ |...XOZ????????????|
$$ |..XOOZ????????????|
$$ |.XOO??????????????|
$$ |XOO?Z?????????????|
$$ |XOOZ??????????????|
$$ |OOZ???????????????|
$$ |OZZ???????????????|
$$ |ZZ????????????????|
$$ |??????????????????|
$$ |??????????????????|
$$ |??????????????????|
$$ |??????????????????|
$$ |??????????????????|
$$ |??????????????????|
$$ +------------------+
  • Surrounding means disconnecting and connection works along the lines on the board. When you capture (connected clusters of) enemy stones, you disconnect them from vacant points; when you make territory, you disconnect it from your opponent’s stones. But this is not always played out: once both players agree what would happen, play stops. Your position has no captives (every stone is connected via its mates to a vacant point) and no territory (every vacant point is connected, possibly via other vacant points to stones of both colours). But White can easily capture several stones! – PJTraill Apr 10 '18 at 22:57
  • Note that when the second board image was converted to markup the black stone in A10 was not marked as "captured" (comment because I couldn't edit just that character). – lfurini Oct 27 '18 at 12:17
9

The game is incomplete.

Literally nothing is "surrounded" here, and if the game ended in such a state nobody would get any points at all until you can mutually agree on which groups are "dead" and which ones are "alive", since right now, none of the groups are unconditionally alive.

Your first example presumes the inside black group is dead, the second example presumes the outside black group is dead. One could also make the case that both black groups are dead, meaning all the territory on the board is "surrounded" by white. Alternatively, one could argue that the white group is dead, meaning all the territory on the board is "surrounded" by black.

However, if everyone agrees that all the groups are alive (or, at least, can't agree that any of them are dead), then all territory is still disputed and nobody is actually surrounding anything.

If you can't tell which groups are alive and which ones are dead, keep playing until you can. Otherwise, any attempts at calculating the score would be guesswork at best.

  • 1
    how can you tell which groups are alive or dead? When they are fully surrounded? – Miemels Jan 5 '18 at 22:39
  • 2
    @Miemels Generally when a group has (or can make) at least two eyes, but there's all sorts of caveats to that (e.g. false eyes or seki). Most life-and-death situations are pretty obvious with a bit of experience, but if you're not sure you can just keep playing until something actually dies. – goldPseudo Jan 5 '18 at 23:09
  • If it's white's turn, you cannot argue that it's dead: White can either capture at 3-6, or at 5-2, or even both if it manages to finish the first capture with sente, and either capture is enough to live. There's also a gigantic weakness in black's center wall: White can built a solid connection up to the 8-8 point with a forced sequence, giving it a ton of potential in the center, or, alternatively, break out at the upper edge. I'd argue that white probably has the stronger position than black: All white stones are connected, and black is just a bunch of weaknesses... – cmaster Jan 22 '18 at 22:31
2

The concept of "dead stones" is a short cut

It is possible to play any game of Go to the point where the board is divided into territories each of which is completely surrounded by a single color, none of which contain any 'dead' stones, and all mixed border territories have been filed in.

But playing the game all the way to this point is tedious if the players are experienced enough to know the outcome well in advance. So just as a grandmaster of chess will concede as soon as they see that checkmate is inevitable, even if the mate is several turns away, Go players won't fight out territory battles if they already know that they won't win them.

A "dead" stone is any stone inside an opponent's territory that you would lose if you were to fight out the battle to the end. If you can't tell whether or not a stone is dead, then that means that you should fight the battle until the end, and you will find out. Your stones are only dead if you say they are.

One of the interesting features of Go is that trying to carve a space in an opponent's territory while your opponent defends it is point neutral (neither player gains any advantage) unless you win. Therefore there is no* penalty for trying to save stones which are probably dead, but maybe aren't.

*The exception is that this is only neutral if both you and your opponent are playing in the territory. If your pieces are so dead that your opponent can play elsewhere while you try to save them before killing them anyway, that will cost you.

  • 1
    Of note, playing to save a dead group will only cost you if you territory scoring (i.e. japanese rules). there's no difference if you use area scoring (i.e. chinese rules). – goldPseudo Jan 6 '18 at 20:47

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