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 Post subject: Re: How do Japanese rules handle this?
Post #21 Posted: Sun Dec 08, 2019 2:03 pm 
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RobertJasiek wrote:
Same intersections, ko stone and ban are insufficient to define whether it is still the same ko. You also would not say same ko stone just because it is on the same intersection after capture and recapture; the earlier ko stone is not on the board but in the lid!


You and I may agree to that, but the Nihon Kiin rules do not. If I get a pin in my hip, am I the same person? Philosophers disagree.

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Post #22 Posted: Sun Dec 08, 2019 3:19 pm 
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lightvector wrote:
gennan wrote:
lightvector wrote:
* Positions B and C - white is stable under normal play without an extra move even if black has any finite positive number of ko threats.
* Positions A and B - Japanese rules would mandate that white needs to add a stone here, costing white 1 point.


Position B: I would think under Japanese rules white does not have to add a move, because white is safe locally. Black would need another double ko elsewhere to keep fighting in this position, but in the encore, black is not allowed to use ko threats in an unrelated situation elsewhere. If there is another double ko elsewhere, then black may choose to fight it before passing and the game can end up in a quadruple ko, voiding the game.


But my understanding is that even "local" ko threats don't work. The Japanese (89) rules seem to specify that "in the encore" (i.e. during confirmation) in order to recapture a ko, you have to pass for that ko. So it doesn't matter that white is safe locally under normal play, white is NOT safe under altered ko rules where recapturing in any ko requires passing for that ko. Right?

Click Here To Show Diagram Code
[go]$$Bc
$$ ----------------------
$$ | O . O . X 2 3 O . . O
$$ | O O O X T X O O O O O
$$ | X X X O 1 O O . O . .
$$ | X . X O O O O O . . .
$$ | . X X . . . . . . . .
$$ | X X . . . . . . . . .
$$ | . . . . . . . . . . .
$$ | . . . . . . . . . . .[/go]


If this sequence takes place during the confirmation phase, at this point, my understanding would be that white can NOT recapture at the triangled point. White has not passed for that ko, and it doesn't matter that W2/B3 have occurred, nor would it matter if white had any ko threats anywhere else - ko threats do not enable recapturing kos in confirmation. Similarly, white cannot recapture at the new ko shape at W2 because white has not passed for that ko either. So if you mechanically apply what the rules seem to say, white is in trouble.

Of course, I don't know what Jasiek's formal 2003 version would say, but did any Japanese professionals have a hand in crafting the 2003 version? If not, it seems to me not necessarily relevant?


Why would white not be allowed to capture 1 on move 4? That stone (1) is not "hot" anymore, so it can be captured like in normal play. I'm probably a bit dense, but I really don't get how this is ambiguous or why it would require extra rules (or extra clarification of rules).

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 Post subject: Re: How do Japanese rules handle this?
Post #23 Posted: Sun Dec 08, 2019 6:54 pm 
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gennan wrote:
lightvector wrote:
Click Here To Show Diagram Code
[go]$$Bc
$$ ----------------------
$$ | O . O . X 2 3 O . . O
$$ | O O O X T X O O O O O
$$ | X X X O 1 O O . O . .
$$ | X . X O O O O O . . .
$$ | . X X . . . . . . . .
$$ | X X . . . . . . . . .
$$ | . . . . . . . . . . .
$$ | . . . . . . . . . . .[/go]


If this sequence takes place during the confirmation phase, at this point, my understanding would be that white can NOT recapture at the triangled point. White has not passed for that ko, and it doesn't matter that W2/B3 have occurred, nor would it matter if white had any ko threats anywhere else - ko threats do not enable recapturing kos in confirmation. Similarly, white cannot recapture at the new ko shape at W2 because white has not passed for that ko either. So if you mechanically apply what the rules seem to say, white is in trouble.

Of course, I don't know what Jasiek's formal 2003 version would say, but did any Japanese professionals have a hand in crafting the 2003 version? If not, it seems to me not necessarily relevant?


Why would white not be allowed to capture 1 on move 4? That stone (1) is not "hot" anymore, so it can be captured like in normal play. I'm probably a bit dense, but I really don't get how this is ambiguous or why it would require extra rules (or extra clarification of rules).


Consider this:

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


Black has an enormous ko threat of playing "a", which would dissolve the seki in the lower left if white did not answer, and this ko threat costs black nothing. White has no way to eliminate this ko threat, if white plays then it will also dissolve the seki in the lower left in favor of black, due to shortage of liberties. So black has an unremovable ko threat here.

In the upper left corner, black is dead by bent-four-in-the-corner. Black is dead *even though* black has this enormous cost-free ko threat. And yet white also does NOT need to sacrifice the lower left seki either or ignore any black threats in order to be able to claim black as dead. And I think pretty much everyone agrees that this is the intent of the Japanese rules.

The way the Japanese rules appear to operationalize black being dead here despite having this massive ko threat is that after play stops, in the confirmation phase, a player is not allowed to recapture a ko even after playing ko threats. The only way to recapture a ko is to pass "for" that ko - i.e. to point at the ko, indicate an intent to be allowed to recapture in the future, and then pass the turn, giving the opponent a full free turn to do whatever needed to resolve that ko, if possible. If the opponent cannot or does not, *then* a recapture is allowed.

So what this operationally would look like is:
Click Here To Show Diagram Code
[go]$$Wc
$$ ----------------------
$$ | O O 1 X O . . . . . .
$$ | O X X X O . . . . . .
$$ | 2 X O O O . . . . . .
$$ | X X O . . . . . . . .
$$ | O O O . . . . . . . .
$$ | . . O O O O O O . . .
$$ | . O O X X X X O . . .
$$ | O O X X . O X O . . .
$$ | X X X . O . X O . . .
$$ | O O O O . X X O . . .
$$ | O O O O X X O O . . .
$$ | O O O O X O O . . . .
$$ | O O O O X O . . . . .
$$ ----------------------[/go]


And then:
Click Here To Show Diagram Code
[go]$$Wc
$$ ----------------------
$$ | 4 3 . X O . . . . . .
$$ | 5 X X X O . . . . . .
$$ | X X O O O . . . . . .
$$ | X X O . . . . . . . .
$$ | O O O . . . . . . . .
$$ | . . O O O O O O . . .
$$ | . O O X X X X O . . .
$$ | O O X X 6 O X O . . .
$$ | X X X . O 7 X O . . .
$$ | O O O O . X X O . . .
$$ | O O O O X X O O . . .
$$ | O O O O X O O . . . .
$$ | O O O O X O . . . . .
$$ ----------------------[/go]


And now at this point, despite :b6: :w7: , black is still not allowed to recapture the ko in the upper left. Black's only way to be allowed to recapture it is to pass a whole turn for it, where upon white would take that free turn to finish the situation and kill black.

Does that make it clear what the issue is here and why in the earlier example you asked about, white might also not be allowed to recapture?


This post by lightvector was liked by: Waylon
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 Post subject: Re: How do Japanese rules handle this?
Post #24 Posted: Sun Dec 08, 2019 7:06 pm 
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RobertJasiek wrote:
If you read my J89 commentary carefully, J89 is ambiguous also WRT whether the ko is still the same ko because, after White 2, the previous ko at 1 is NOT a ko...! So if you insist on literal J89 application, you can only conclude: ambiguous!

If Japanese professionals had participated in J2003, it would have been as hopelessly ambiguous as J89. Of course, J2003 is my work. After 10 years of preparation in J rules study, then 11 months of full time work (including work while sleeping!). Call such diligence "not relevant", LOL.


Sorry, I didn't mean any offense. We agree the J89 rules are hopelessly ambiguous in several ways. Your formalization is one way to resolve those ambiguities. But the J89 rules being ambiguous almost by definition means that there is more than distinct way to resolve those ambiguities, and it was not obvious to me that logical ways you ended up resolving them would necessarily be the same way that Japanese players would resolve them or want to resolve them if they came up in an actual game.

J89 ambiguity, in any case, obviously makes it hard to know how to proceed.

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 Post subject: Re: How do Japanese rules handle this?
Post #25 Posted: Sun Dec 08, 2019 11:49 pm 
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Yes, it is difficult to perceive and so is not obvious that J2003 produces for all examples considered by Japanese pro players their preferred results and does not produce counter-examples for that purpose. J2003 does, however, not provide a procedure preferred by them, e.g., because they were not even aware of (hypothetical-)strategy as a concept that can be formalised and its application complexity, and the J1989 (and Korean rules) authors overlooked the necessity for local-2 and capturable-2 to map all two-eye-alive groups to the concepts of (un)capturability.

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 Post subject: Re: How do Japanese rules handle this?
Post #26 Posted: Mon Dec 09, 2019 12:15 am 
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lightvector wrote:
gennan wrote:
lightvector wrote:
Click Here To Show Diagram Code
[go]$$Bc
$$ ----------------------
$$ | O . O . X 2 3 O . . O
$$ | O O O X T X O O O O O
$$ | X X X O 1 O O . O . .
$$ | X . X O O O O O . . .
$$ | . X X . . . . . . . .
$$ | X X . . . . . . . . .
$$ | . . . . . . . . . . .
$$ | . . . . . . . . . . .[/go]


If this sequence takes place during the confirmation phase, at this point, my understanding would be that white can NOT recapture at the triangled point. White has not passed for that ko, and it doesn't matter that W2/B3 have occurred, nor would it matter if white had any ko threats anywhere else - ko threats do not enable recapturing kos in confirmation. Similarly, white cannot recapture at the new ko shape at W2 because white has not passed for that ko either. So if you mechanically apply what the rules seem to say, white is in trouble.

Of course, I don't know what Jasiek's formal 2003 version would say, but did any Japanese professionals have a hand in crafting the 2003 version? If not, it seems to me not necessarily relevant?


Why would white not be allowed to capture 1 on move 4? That stone (1) is not "hot" anymore, so it can be captured like in normal play. I'm probably a bit dense, but I really don't get how this is ambiguous or why it would require extra rules (or extra clarification of rules).


Consider this:

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


Black has an enormous ko threat of playing "a", which would dissolve the seki in the lower left if white did not answer, and this ko threat costs black nothing. White has no way to eliminate this ko threat, if white plays then it will also dissolve the seki in the lower left in favor of black, due to shortage of liberties. So black has an unremovable ko threat here.

In the upper left corner, black is dead by bent-four-in-the-corner. Black is dead *even though* black has this enormous cost-free ko threat. And yet white also does NOT need to sacrifice the lower left seki either or ignore any black threats in order to be able to claim black as dead. And I think pretty much everyone agrees that this is the intent of the Japanese rules.

The way the Japanese rules appear to operationalize black being dead here despite having this massive ko threat is that after play stops, in the confirmation phase, a player is not allowed to recapture a ko even after playing ko threats. The only way to recapture a ko is to pass "for" that ko - i.e. to point at the ko, indicate an intent to be allowed to recapture in the future, and then pass the turn, giving the opponent a full free turn to do whatever needed to resolve that ko, if possible. If the opponent cannot or does not, *then* a recapture is allowed.

So what this operationally would look like is:
Click Here To Show Diagram Code
[go]$$Wc
$$ ----------------------
$$ | O O 1 X O . . . . . .
$$ | O X X X O . . . . . .
$$ | 2 X O O O . . . . . .
$$ | X X O . . . . . . . .
$$ | O O O . . . . . . . .
$$ | . . O O O O O O . . .
$$ | . O O X X X X O . . .
$$ | O O X X . O X O . . .
$$ | X X X . O . X O . . .
$$ | O O O O . X X O . . .
$$ | O O O O X X O O . . .
$$ | O O O O X O O . . . .
$$ | O O O O X O . . . . .
$$ ----------------------[/go]


And then:
Click Here To Show Diagram Code
[go]$$Wc
$$ ----------------------
$$ | 4 3 . X O . . . . . .
$$ | 5 X X X O . . . . . .
$$ | X X O O O . . . . . .
$$ | X X O . . . . . . . .
$$ | O O O . . . . . . . .
$$ | . . O O O O O O . . .
$$ | . O O X X X X O . . .
$$ | O O X X 6 O X O . . .
$$ | X X X . O 7 X O . . .
$$ | O O O O . X X O . . .
$$ | O O O O X X O O . . .
$$ | O O O O X O O . . . .
$$ | O O O O X O . . . . .
$$ ----------------------[/go]


And now at this point, despite :b6: :w7: , black is still not allowed to recapture the ko in the upper left. Black's only way to be allowed to recapture it is to pass a whole turn for it, where upon white would take that free turn to finish the situation and kill black.

Does that make it clear what the issue is here and why in the earlier example you asked about, white might also not be allowed to recapture?


From my understanding, the confirmation phase determines the status of groups separately. So when determining the status of the upper left, the status of the lower left is irrelevant and on move 7 white can just ignore :b6: and capture at C13, confirming that black is dead in the upper left.

Then we rollback everything to determine the status of the lower left and that will turn out to be a seki.

So AFAIK if white responds at F5 on move :w7:, it would be a mistake, because there is no ban for black to recapture at A13 on move 8. If white plays correctly in the confirmation phase, the position should not reach the point where black can recapture, because white will resolve the issue on move 7.

So this position is not ambiguous under Japanese rules. Perhaps the rules aren't stated as clearly as they could, but this is how the confirmation procedure should turn out and black's bent four group is just dead. Please correct me if I'm wrong.


Last edited by gennan on Mon Dec 09, 2019 12:32 am, edited 2 times in total.
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 Post subject: Re: How do Japanese rules handle this?
Post #27 Posted: Mon Dec 09, 2019 12:31 am 
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gennan wrote:
From my understanding, the confirmation phase determines the status of groups separately. So when determining the status of the upper left, the status of the lower left is irrelevant and on move 7 white can just ignore :b6: and capture at C13, confirming that black is dead in the upper left.
AFAIK it is the Korean rules that work this way (and maybe pre-89 Japanese from where those presumably originated). J89 does have global play in confirmation and the pass-for-ko rule, and this position is a legitimate anomaly for that rule.

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 Post subject: Re: How do Japanese rules handle this?
Post #28 Posted: Mon Dec 09, 2019 12:44 am 
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moha wrote:
gennan wrote:
From my understanding, the confirmation phase determines the status of groups separately. So when determining the status of the upper left, the status of the lower left is irrelevant and on move 7 white can just ignore :b6: and capture at C13, confirming that black is dead in the upper left.
AFAIK it is the Korean rules that work this way (and maybe pre-89 Japanese from where those presumably originated). J89 does have global play in confirmation and the pass-for-ko rule, and this position is a legitimate anomaly for that rule.

Ok, so the J89 rules are inconsistent with actual practise before and after 1989. I know that Robert and Bill spent a lot of effort to fix inconsistencies in the J89 rules and now I'm beginning to understand why. Perhaps the Japanese chose to ignore these issues, because in practise they don't bother to follow the J89 rules to the letter anyway.

Did the Koreans ever write down the rules they use, or do they just refer to the J89 rules?

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 Post subject: Re: How do Japanese rules handle this?
Post #29 Posted: Mon Dec 09, 2019 1:04 am 
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gennan wrote:
Did the Koreans ever write down the rules they use, or do they just refer to the J89 rules?
There are some written versions, rather skimpy though, unfortunately.

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Post #30 Posted: Mon Dec 09, 2019 1:26 am 
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gennan wrote:
the Japanese chose to ignore these issues, because


They ignored these issues because they did not study rules, their theory and consequences for examples carefully enough. The authors Sakai Takeshi, Saijo Masataka and maybe a few others tried hard but, by a factor 10+, not hard enough. I met both and it became clear that they overlooked everything I (and partly others) had discovered. Sakai's capturability approach for J89 (and later adopted for some versions of Korean rules) was a theoretically cute (but practically stupid) alternative approach to the (if understood simpler and more commonly known) concept of two eyes, was necessary at that time because of the then still existing knowledge gap of what might be a definition of life due to two eyes (the failures of, sic, J49 and WAGC Rules looming), but overlooked capturable-2 etc.

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 Post subject: Re: How do Japanese rules handle this?
Post #31 Posted: Mon Dec 09, 2019 1:43 am 
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IIUC, the J89 rules have global play, but they consider the status of each group or stone separately, if the players do not agree about it. Since the play is hypothetical, there is nothing to roll back. As each group or stone is considered, the hypothetical play starts afresh.

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 Post subject: Re: How do Japanese rules handle this?
Post #32 Posted: Mon Dec 09, 2019 2:31 am 
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Even though L/D is considered separately, the attacker cannot ignore threats elsewhere because of the "enabling" clause.

BTW, this is against the current consensus OC, but I think bent4 dead even with unramovable threats is a poor result. It is inconsistent with three points without capturing: the latter shows that the spirit of current rules is that "problematic" captures need to be played out (losing points in the process). But then again, in that case there is no real alternative.

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Post #33 Posted: Mon Dec 09, 2019 3:42 am 
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moha wrote:
BTW, this is against the current consensus OC, but I think bent4 dead even with unramovable threats is a poor result.


I doubt if that is against the current consensus. Everybody who likes the J89 rules, raise your hand. :lol:

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Post #34 Posted: Fri Dec 20, 2019 11:50 pm 
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Bill Spight wrote:
I doubt if that is against the current consensus. Everybody who likes the J89 rules, raise your hand. :lol:


I think the rulemakers of the J89 rule did a great job. At least I tip my hat to them.
However, it is also true that J89 rule is badly flawed as R. Jasiek keeps saying when he has a chance.
I know they had "global play" in their mind when writing the rule, but I strongly believe that only local plays must be allowed for the rule to have any hope to become logical.

Quote:
Besides, why an anti-seki is not both lose, I don't know.


In case you are trying to ask "Shouldn't every anti-seki result in both palyer's loss?", I think https://lifein19x19.com/viewtopic.php?p=252059#p252059 answers that there are potential anti-seki cases that both players do not mind asking resumption of the game, but the opponents still do not want to make further play.

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