Do recaptures of non-ko capturing plays occur in practice?

General conversations about Go belong here.
Post Reply
luigi
Lives in gote
Posts: 352
Joined: Wed Jul 06, 2011 12:01 pm
Rank: Low
GD Posts: 0
Location: Spain
Has thanked: 181 times
Been thanked: 41 times

Do recaptures of non-ko capturing plays occur in practice?

Post by luigi »

I have a very specific question for you seasoned players: is there any position where it's good to make a capture that is not part of a ko or a long cycle and where the stone you place to make said capture can itself be reasonably expected to be captured by the opponent at some later time?

Snapback, for instance, is not a valid example because the first capture is made useless by the recapture.
Calvin Clark
Lives in gote
Posts: 426
Joined: Thu Aug 13, 2015 8:43 am
GD Posts: 0
Has thanked: 186 times
Been thanked: 191 times

Re: Do recaptures of non-ko capturing plays occur in practic

Post by Calvin Clark »

luigi wrote:I have a very specific question for you seasoned players: is there any position where it's good to make a capture that is not part of a ko or a long cycle and where the stone you place to make said capture can itself be reasonably expected to be captured by the opponent at some later time?

Snapback, for instance, is not a valid example because the first capture is made useless by the recapture.
If the first capture captures multiple stones it is very common. Consider this example:
Click Here To Show Diagram Code
[go]$$B Capture three stones
$$ -------------
$$ . X O O O 1 O .
$$ . X X X X O O .
$$ . . . . . . . .[/go]
After this capture, the position looks like this. Whether or not white or black gets to play first at 'a' depends on the rest of the board. We cannot say without further information whether or not :b1: above was good in first place. Sometimes it is, and sometimes it's not.
Click Here To Show Diagram Code
[go]$$B Capture three stones
$$ -------------
$$ . X . . a X O .
$$ . X X X X O O .
$$ . . . . . . . .[/go]
Even if you are talking about the capture of one stone, sometimes the capturing that stone temporarily stabilizes an unstable group. Later on, maybe the stone that makes the capture is put in atari, but it is no longer necessary connect because the group is safe for other reasons (e.g., even if disconnected it still has two eyes, etc.)

So I don't believe a general statement can be made that a capture is not good if the stone that captures could itself be captured later.

Take a look at this AlphaGo self-play game.
Click Here To Show Diagram Code
[go]$$ Position at move 266 - Black to play
$$ ---------------------------------------
$$ | . . . . . . . X . . . X X O . . . . . |
$$ | . . X . . . X O X . . X O . . . O . . |
$$ | . . X O . . X O O X X X O O . X O . . |
$$ | . X X O . . X O . X X O . . . X O . . |
$$ | . O X O . . X O O O X O . . . X O X . |
$$ | . B O O . X X X O X X O . . O X X O O |
$$ | B B B O X X X O O X . O X X O X X X O |
$$ | O B B O X . O O X X X O X O O O X O . |
$$ | . O O X O O . X X O O X X O . O O O . |
$$ | . O X X X O X X O , . . X O X X X O . |
$$ | O O O X O . O O . O O O O O X X O O O |
$$ | . O O X O O . O O X X X O . . X O X O |
$$ | . O O X X X O . X X O . O O X X X X X |
$$ | O . O O X . O X . . . O . . O . X . . |
$$ | O O X X X O O O O O X O O O O O X X . |
$$ | O X . X O O X X X O O X O X O X O O . |
$$ | X X X . X X O O X X X X X X X X . O . |
$$ | . . . X . X . . . . O X O X . . X O X |
$$ | . . . . . . . . . . . O . . . . . O . |
$$ ---------------------------------------][/go]
Click Here To Show Diagram Code
[go]$$B Moves 267 to 272
$$ ---------------------------------------
$$ | . . . . . . . X . . . X X O . . . . . |
$$ | . . X . . . X O X . . X O . . . O . . |
$$ | . . X O . . X O O X X X O O . X O . . |
$$ | 3 X X O . . X O . X X O . . . X O . . |
$$ | 2 O X O . . X O O O X O . . . X O X . |
$$ | 5 X O O . X X X O X X O . . O X X O O |
$$ | X X X O X X X O O X . O X X O X X X O |
$$ | 6 X X O X . O O X X X O X O O O X O . |
$$ | 1 O O X O O . X X O O X X O . O O O . |
$$ | 4 O X X X O X X O , . . X O X X X O . |
$$ | O O O X O . O O . O O O O O X X O O O |
$$ | . O O X O O . O O X X X O . . X O X O |
$$ | . O O X X X O . X X O . O O X X X X X |
$$ | O . O O X . O X . . . O . . O . X . . |
$$ | O O X X X O O O O O X O O O O O X X . |
$$ | O X . X O O X X X O O X O X O X O O . |
$$ | X X X . X X O O X X X X X X X X . O . |
$$ | . . . X . X . . . . O X O X . . X O X |
$$ | . . . . . . . . . . . O . . . . . O . |
$$ ---------------------------------------[/go]
We can't argue that :b1: is a bad move because those six stones are in atari before :b1: and that's kind of big at this stage of the game. :) Yet, :b1: is later captured by :w6:.

Can you explain your question with examples?
User avatar
EdLee
Honinbo
Posts: 8859
Joined: Sat Apr 24, 2010 6:49 pm
GD Posts: 312
Location: Santa Barbara, CA
Has thanked: 349 times
Been thanked: 2070 times

Post by EdLee »

Hi luigi,

Re: Calvin's question; yes, what situation prompted your question ? :)
luigi
Lives in gote
Posts: 352
Joined: Wed Jul 06, 2011 12:01 pm
Rank: Low
GD Posts: 0
Location: Spain
Has thanked: 181 times
Been thanked: 41 times

Re:

Post by luigi »

Calvin's answer settles it for me. It was an easier one than I thought.

I was just wondering how my Kingo variant would change if captures had to be made with kings (while retaining the ko rule, even though it's not strictly needed).
jeromie
Lives in sente
Posts: 902
Joined: Fri Jan 31, 2014 7:12 pm
Rank: AGA 3k
GD Posts: 0
Universal go server handle: jeromie
Location: Fort Collins, CO
Has thanked: 319 times
Been thanked: 287 times

Re: Do recaptures of non-ko capturing plays occur in practic

Post by jeromie »

Throwing in a stone to destroy a false eye is also very common. There would be many more shapes that are alive if that was not permitted!

Edit: Bad example. That’s what I get for posting before coffee.
luigi
Lives in gote
Posts: 352
Joined: Wed Jul 06, 2011 12:01 pm
Rank: Low
GD Posts: 0
Location: Spain
Has thanked: 181 times
Been thanked: 41 times

Re: Do recaptures of non-ko capturing plays occur in practic

Post by luigi »

jeromie wrote:Throwing in a stone to destroy a false eye is also very common. There would be many more shapes that are alive if that was not permitted!
But a throw-in is not a capture, right?

EDIT: Okay, I saw your edit. :)
Post Reply