no, if white fills the dame he can fight the ko.

Click Here To Show Diagram Code

[go]$$Wc =pass, @ 1, @4, =pass, @ a
$$ ---------------------
$$ | . . O . . O X 1 4 |
$$ | O O O O O O X X O |
$$ | X X X X X O O X 3 |
$$ | 6 . . . X O O X a |
$$ | 5 X . . X O O X X |
$$ | X . X X X X O O O |
$$ | X X O O O X X O O |
$$ | O O 8 . O X . X O |
$$ | . 9 O O O X X X O |
$$ ---------------------[/go]

In order to start the ko white must find the first threat and make an extra play in black's area (Move 3 in the diagram). On this board both white and black have 1 threat. That means that black will win the ko and get an extra point from white's additional play in his territory. So he can now capture to settle the ko and win the game.

Once white has filled the dame white has lost the game.

okay if the ko is a bad deal for white, then black can fill the dame with no harm done.
i still fail to see how this is seki.
edit: okay i think i understand now. if black fills the dame, the group is now large enough that killing it is worth more to white than saving his corner.

Click Here To Show Diagram Code

[go]$$c Unfillable Dame? \n(Japanese Rules, No prisoners, 5.5 Komi).
$$ ---------------------
$$ | . . O . . O X 2 . |
$$ | O O O O O O X X O |
$$ | X X X X X O O X 4 |
$$ | . . . . X O X X . |
$$ | . X . . X O O X X |
$$ | X . X X X X O O 1 |
$$ | X X O O O X X O O |
$$ | O O 5 . O X . X O |
$$ | . 3 O O O X X X O |
$$ ---------------------[/go]

Hi,
Yes, as stated above, under traditional japanese rules, this is a seki, and there are no points in the marked intersections.

But, as Robert pointed out in his article, things may be different under modern japanese rules (1989). As I understand the rules, white has one point in Q18, but R19 and T17 are not territory and are worth zero.

Explanation : none of the 4 involved chains is capturable. Thus, according to article 7, they are alive.
According to article 8, the circled intersections are eyes, and T19 is a dame.

But the trick is that according to the new definition of seki, only the white stone S19, and the black chain in T18, are in seki, because they are the only chains that have a dame. The R18 and Q19 chains are not in contact with the dame, thus they are not in seki.

Since Q18 is completely surrounded by living stones that are not in seki, it is a territory.

Well, the J89 rules have been around for a long time, and it is clear that there are no points in seki, nor was there an intent to change that from the J49 rules. So somehow all of the White stones in the corner own the dame at "a". In my revision of the J89 rules I write, "All stones that surround the same eye points belong to the same group. A group is called a seki group if it adjacent to a neutral point, or if one or more of its stones is in atari." That is clearer than the J89 text, I think. See http://senseis.xmp.net/?SpightJapaneseStyleRules

_________________
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Everything with love. Stay safe.

Thanks for the clarification, Bill.

I have read the J89 rules, but I'm not familiar with their everyday use. I play in France.