Life In 19x19

Pio2001 wrote:How can it be ? I was under the impression that under japanese rules, if the only thing left on the board is an unfinished ko, the intersection that is inside is not a point of territory (because of the unwritten rule that says that if we lift ko bans and give the sente to the opponent, the ko may be recaptured, therefore one of the stones around the empty intersection is dead).
Why is it different in this game ? According to the same reasoning, the white stone A16 should be dead, therefore the intersection A15 is dame, therefore White has no territory in A13 until she fills A15.

In the hypothetical play, after Black's ko capture, White can afford to make a pass to recapture the ko and eventually capture the whole Black group. Korean rule does not mandate a pass for the ko capture, but there is no problem doing so. Thus, in both rules, the whole Black group is captured at the end of the hypothetical play. (Technically, Black fails to create a new stone uncapturable for White.)

There are a few possible Black strategies, but none is successful. If you still have trouble following the hypothetical play, I will give you a few diagrams.

Going back to the original position, I have made an SGF file for no pass go with prisoner return, no group tax, using the method of exiting the ko to evaluate it. The file clearly shows that Black's threat is not to win the ko, but to convert it to a regular ko. But when there are no ko threats, White is komaster of that ko. And that makes White komaster of the approach ko, as well. As komaster White wins the approach ko, but at the cost of 1 pt. so the original position is worth 1 pt. more for White.

Bill Spight wrote:

Matti wrote:In some cases the area and territory scoring are fundamentally different. See the first diagram at http://www.harryfearnley.com/go/bestiar ... ivola.html. With territory scoring the position is seki, but with area scoring once the dame have been filled, white can start filling a big eye with no extra cost, and force balck to select which white group to capture.this leaves the other white group alive with two eyes and the adjanced black group dead.

With apologies to the late John Rickard, it is a matter of the rules. Yes, this is a standoff, and the J89 rules permit Black to pass without cost while White fills the big eye. However, as I believe Honinbo Shuwa understood, the standoff "should" be resolved when plays cost 1 point, as with capturing dead stones, when you don't let the opponent pass for free. In that case White plays first and Black replies on the board. The result is 9 pts. for White after Black makes the last play. No Pass Go with Prisoner Return indicates the same value, and it uses territory scoring.

If the Japanese could agree on Honinbo Shuwas interpretation, the proböem would be solved. If not the difference could be escalated by making the groups bigger.

Nothing to do with modern rules or disputes, but there is interesting food for thought in something Go Seigen said.

I have been working on the book of the Go vs Iwamoto ten-game match. One game ended in a jigo. In the post-game comments Go made the suggestion that the 芇 Japanese character for jigo should be changed to the Chinese character 和. The Japanese didn't go that far, and they now tend to use katakana anyway, but if characters are insisted upon, 持碁 is now normal (though that risks some confusion with 持 = seki).

But the interesting aspect is why 芇 was chosen in the first place. I assume it came in via Chinese. The ancient Chinese Shuo Wen dictionary gives it as meaning 'to hit' but it was obscure even then. It seems to have acquired the meaning 'to lose' but in a gambling context (i.e. to be hit??) before acquiring a go sense which the old book 通玄集 gives as meaning 'neither side wins or loses.'

I don't know the date of the 通玄集 (can anyone help?) but the apparent transition from 'lose' (at least in some games) to 'jigo' may hint at a change in old Chinese rules.

jaeup wrote:(Technically, Black fails to create a new stone uncapturable for White.)

...and White, after being captured, can play a stone that can't be captured by Black. I see !

Thanks for the explanation. The sequences were ok for me. It was the part "capturing them would enable a new stone to be played that the opponent could not capture" that I was missing.
I didn't think about that because I had associated this part of the rule with snapback. It didn't come to my mind while thinking about a ko.