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Question about seki/capture race
http://prod.lifein19x19.com/viewtopic.php?f=4&t=13962		 Page 1 of 1
Author:  Ellisdee [ Thu Jan 12, 2017 1:13 pm ]
Post subject:  Question about seki/capture race
Specifically at move 90 when black plays away (I was playing white), I counted two shared liberties, 3 outside liberties for black, and 4 outside liberties for white. So wouldn't that have meant I was ahead in the capturing race and could play after black and still capture? I thought that was the "rule" of how it would work.

Turns out black needed to keep playing to make seki, and I needed to go back from his tenuki for a large capture.

Author:  Hrabanus [ Thu Jan 12, 2017 2:05 pm ]
Post subject:  Re: Question about seki/capture race
According to Richard Hunter’s way of liberty counting in semeai, white is the favourite, therefore: outside liberties + 1; black counts outside (including approach) + inside liberties. Makes 5 each.
Favourite moves first = dead
Underdog moves first = seki

I translated the terms from german, hope they are the right ones in english.

Edit: He categorizes this fight as Type 2: two or more inside liberties
Author:  DrStraw [ Thu Jan 12, 2017 3:31 pm ]
Post subject:  Re: Question about seki/capture race
Think of it this way: if black plays first then there are three outside liberties each. At this point it does not matter who starts first after that because by the time each has played three moves there will be no outside liberties, just the common inside ones, leaving seki.
Author:  Bill Spight [ Thu Jan 12, 2017 6:48 pm ]
Post subject:  Re: Question about seki/capture race
This is an interesting semeai. :)

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


There are 2 shared liberties, White has 4 outside liberties, and Black has, errh . . . , some outside liberties. ;)

Click Here To Show Diagram Code
[go]$$B Black plays first
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . X O . . . |
$$ | . . . O . . . . . . . X . . X O . . . |
$$ | . . . , . . . . . , . . . . X , O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . O . . . |
$$ | . . . . . . . . . . . . X . . . . . . |
$$ | . . . . . . . . . . X X . . . O . . . |
$$ | . . . . . . . . . . X O X X X O . . . |
$$ | . . . , . . . . O O X O X O X , O . . |
$$ | . . . . . . . . O X O O O O X X X . . |
$$ | . . . . . . . . 2 X X X O O O 1 . . . |
$$ | . . . . . . . O O X 6 X X O 7 X X . . |
$$ | . . . . . . . . O X O X X O O 3 . . . |
$$ | . . . . . . . . O O 4 O X X O 5 X . . |
$$ | . . . X . O O . . , O O X . O X X . . |
$$ | . . . . X X O . . . . O X . O X . . . |
$$ | . . . . . . . . . . . O X X O X . . . |
$$ | . . . . . . . . . . . O O X O X . . . |
$$ ---------------------------------------[/go]


Black fills White's 4 outside liberties while White fills Black's 3 outside liberties, for seki.

Click Here To Show Diagram Code
[go]$$W White plays first
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . X O . . . |
$$ | . . . O . . . . . . . X . . X O . . . |
$$ | . . . , . . . . . , . . . . X , O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . O . . . |
$$ | . . . . . . . . . . . . X . . . . . . |
$$ | . . . . . . . . . . X X . . . O . . . |
$$ | . . . . . . . . . . X O X X X O . . . |
$$ | . . . , . . . . O O X O X O X , O . . |
$$ | . . . . . . . . O X O O O O X X X . . |
$$ | . . . . . . . . 1 X X X O O O 2 . . . |
$$ | . . . . . . . O O X 5 X X O 8 X X . . |
$$ | . . . . . . . . O X O X X O O 4 . . . |
$$ | . . . . . . . . O O 3 O X X O 6 X . . |
$$ | . . . X . O O . . , O O X 7 O X X . . |
$$ | . . . . X X O . . . . O X 9 O X . . . |
$$ | . . . . . . . . . . . O X X O X . . . |
$$ | . . . . . . . . . . . O O X O X . . . |
$$ ---------------------------------------[/go]


White fill 3 outside liberties for Black plus the 2 shared liberties while Black fill White's 4 outside liberties. White wins the semeai.

But wait! There's more! ;)

Click Here To Show Diagram Code
[go]$$W White plays correctly
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . X O . . . |
$$ | . . . O . . . . . . . X . . X O . . . |
$$ | . . . , . . . . . , . . . . X , O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . O . . . |
$$ | . . . . . . . . . . . . X . . . . . . |
$$ | . . . . . . . . . . X X . . . O . . . |
$$ | . . . . . . . . . . X O X X X O . . . |
$$ | . . . , . . . . O O X O X O X , O . . |
$$ | . . . . . . . . O X O O O O X X X . . |
$$ | . . . . . . . . 1 X X X O O O 2 . . . |
$$ | . . . . . . . O O X 7 X X O . X X . . |
$$ | . . . . . . . . O X O X X O O 4 . . . |
$$ | . . . . . . . . O O . O X X O 6 X . . |
$$ | . . . X . O O . . , O O X 3 O X X . . |
$$ | . . . . X X O . . . . O X 5 O X . . . |
$$ | . . . . . . . . . . . O X X O X . . . |
$$ | . . . . . . . . . . . O O X O X . . . |
$$ ---------------------------------------[/go]


White fills 2 shared liberties plus 2 of Black's outside liberties while Black fills 3 of White's outside liberties. White wins the semeai, and makes 1 more point of territory than in the previous diagram. Verrrry interesting. :D

When Black plays first :b1: not only reduces White's liberties by 1, it also increases Black's liberties by 1. :)
Author:  DrStraw [ Thu Jan 12, 2017 6:59 pm ]
Post subject:  Re: Question about seki/capture race
Bill, trust you to complicate something which seems simple! :razz:
Author:  Bill Spight [ Thu Jan 12, 2017 7:28 pm ]
Post subject:  Re: Question about seki/capture race
DrStraw wrote:
Bill, trust you to complicate something which seems simple! :razz:

De nada. :)
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