The "no ban in double ko" rule to solve pass-for-ko issue ?

CDavis7M · Post by **CDavis7M** » Sat Oct 02, 2021 9:51 am

John Fairbairn wrote:1. The Preamble to the J89 rules tells us, and firmly stresses, that the intention was to adhere to the traditional way of play in Japan and that they are an attempt to rationalise and clarify the logic behind the Japanese way of play.

Yes they do. Another part that is ignored is that the Japanese rules say to use "good sense."

John Fairbairn wrote:4. Also apparently ignored, are the implications of the 1999 Moriyama game with several passes (which may actually be an example of a confirmation phase in a pro game, though that wasn't mentioned in the commentary, and I suspect GoGoD may be the only place where you can see the full game)

I took a look and I believe you are talking about GoGoD fule 1999-06-30b. In this game, there are several passes but they are not used during confirmation of life and death. Instead, the passes are to proceed with Article 9 confirmation/acceptance, but the players do not agree and play is resumed, then the players both pass, disagree again, resume again, pass again, and then agree.

John Fairbairn wrote:...and the 2008 Kisei game with Cho Chikun in which a pass occurred in a dispute where player and referee disagreed, though J2003 was quoted rather than J89. [I am guessing the dates from memory.]

Awesome game. This is GoGoD file 2008-02-27B. I would love to read an article about this but my understanding here is that this is also a resumed game. What likely happened is that Yamashita (white) said that Cho's eyeless group (black) in the lower right was dead and that his white group with 1-eye (partly) surrounding the black group was alive. But Cho (black) disagreed because there is also a ko and Cho asked to resume the game to kill white. White was given the right to play first since Cho demanded resumption, but White passes as is allowed. So black took the ko after the pass (no ko issue because there was already an intervening move), white played a threat, and so on. Until Cho finally agree that the black group was dead, thereby arriving at the result given.

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I can find no instances of any official game under Japanese rules where the player is allowed to play after an abandoned-move/declaration-to-stop (called a pass but not a pass) except as allowed under Article 9 on Resumption of the Game or Article 7 on Confirmation of Life and Death.

CDavis7M · Post by **CDavis7M** » Sat Oct 02, 2021 9:55 am

jann wrote:I won't repeat what I already wrote, but one more thing: there are cases/shapes where only one side has things to play (several moves even) while the other has to pass. So "B pass, W play, B pass, W play, B pass, W pass" can sometimes be the ONLY meaningful way to finish a game.

Find it for me and I will show you why that's wrong.

CDavis7M · Post by **CDavis7M** » Sat Oct 02, 2021 11:01 am

It seems that people are trying to "hypothetical play" the game to confirm life or death status. I don't see any basis for this in the Japanese rules. The Japanese rules only allow for resumption of play, that is, actual non-hypothetical play, OR life and death confirmation based on the definition of a live group, which is not the same as "play" at all.

There are examples of life and death confirmation and they do not work like the examples shown on this forum. If you want to resume play you can. But if you want to confirm life or death, you must refer to the definition of a live stone in the rules.

The example "plays" Black 1, 3, and 5 above accomplish NOTHING to show life and death STATUS for Article 9. It just shows that there is a possibility for Black is make life during gameplay.

kvasir wrote:The ko ban is cleared when there is a pass-ko for that ko or the hot stones are captured. It is not necessary to handle the case of connecting the ko, but you may just as well state that the ko ban is cleared in this case too.

I have no idea what you are saying if we are talking about the Japanese rules (it seems like we are) because these terms are not terms of the Japanese rules.

It would probably be best to just use the terms of the rules since they are the terms for a reason.

kvasir wrote: For example

$$B :w4: pass for :w1:
$$ ---------------------
$$ | . . X X X X O X . .
$$ | X X O X O X O X . .
$$ | X O 1 O 3 O O X . .
$$ | O 2 O 5 O O X X . .
$$ | O . O O O X X . . .
$$ | O O O . O X X X . . . .
$$ | X X O O X . . . . . .
$$ | X X X X X
Click Here To Show Diagram Code
[go]$$B :w4: pass for :w1: $$ --------------------- $$ | . . X X X X O X . . $$ | X X O X O X O X . . $$ | X O 1 O 3 O O X . . $$ | O 2 O 5 O O X X . . $$ | O . O O O X X . . . $$ | O O O . O X X X . . . . $$ | X X O O X . . . . . . $$ | X X X X X[/go]
I'd say that there is a pass-ko ban for and but not

Since there is no such thing as a "pass-ko ban" in the Japanese rules, let me provide an explanation following the Japanese rules.

This example is extremely confusing because it does not correspond to plays that are allowed during game play (Black would not be allowed to play 5 since white has not played a 4th move) and it does not correspond to Life and Death confirmation (it is not confirming life status as defined in the rules).

And since we are talking about kos and passing, I'm going to assume that this is the final board state and that we are attempting to confirm. the life and death status of the stones.

Don't worry, it is actually much easier than you think. The key is the definition of life and death, which is what is being confirmed.

The rules define dead stones as stones that are not live stones.
The rules define live stones as stones that cannot be captured (取り,取る) -- which is literally the title of Article 5 "取り".

Alive status has two parts. First, a stone is a live stone if it cannot be captured by the process in Article 5. Article 5 states that stones are captured if one player plays such that the stones cannot exist on the board according to Article 4. Article 4 states that stones without an adjacent empty point cannot be on the board. Recognize that Article 4 also references Article 3, which defines an empty point as a vacant intersection.

Second, stones are alive if they could be captured (per article 5) but only if new stones can be played that cannot then be captured (unless those stones could be captured, but only if new stones can be played that cannot be captured, and so on).

The test for being alive is specificaally whether or not the stones can be captured, or whether a new stone played after their capture can not be captured. It's really that simple.

Click Here To Show Diagram Code: [go]$$B The groups :wc: :ws: :wt: :wx: are all alive because they either cannot be captured or they can play a stone that cannot be captured $$ --------------------- $$ | . . X X X X O X . . $$ | X X Q X P X O X . . $$ | X @ . O . O O X . . $$ | O . O . O O X X . . $$ | O . O W O X X . . . $$ | O O O . O X X X . . . . $$ | X X O O X . . . . . . $$ | X X X X X[/go]

====================

Let's actually follow the Japanese Rules to determine whether the

stones are alive, since that's easy. The

group is alive because there is no move that can be played that would prevent these stones from existing. Here is every possible attempt to capture white stones

and they all fail to capture.

is alive.

Click Here To Show Diagram Code: [go]$$B $$ --------------------- $$ | . . X X X X O X . . $$ | X X O X O X O X . . $$ | X O . O 1 O O X . . $$ | O . O . O O X X . . $$ | O . O W O X X . . . $$ | O O O . O X X X . . . . $$ | X X O O X . . . . . . $$ | X X X X X[/go]

Click Here To Show Diagram Code: [go]$$B $$ --------------------- $$ | . . X X X X O X . . $$ | X X O X O X O X . . $$ | X O . O . O O X . . $$ | O 1 O . O O X X . . $$ | O . O W O X X . . . $$ | O O O . O X X X . . . . $$ | X X O O X . . . . . . $$ | X X X X X[/go]

Click Here To Show Diagram Code: [go]$$B $$ --------------------- $$ | . . X X X X O X . . $$ | X X O X O X O X . . $$ | X O . O . O O X . . $$ | O . O . O O X X . . $$ | O 1 O W O X X . . . $$ | O O O . O X X X . . . . $$ | X X O O X . . . . . . $$ | X X X X X[/go]

----------------

What about white stone

. Let's show that it is alive.

Click Here To Show Diagram Code: [go]$$B The stone :wx: is alive because even though it can be captured, a new stone :w2: may be played that cannot be captured. The new stone :w2: cannot be captured. $$ --------------------- $$ | . . X X X X O X . . $$ | X X O X P X O X . . $$ | X O 2 O 1 O O X . . $$ | O . O . O O X X . . $$ | O . O W O X X . . . $$ | O O O . O X X X . . . . $$ | X X O O X . . . . . . $$ | X X X X X[/go]

--------------------

So what about the black groups?

Click Here To Show Diagram Code: [go]$$W The black group :bt: is dead because it can be made to be illegal to exist on the board by :w1:. That is, :w1: captures :bt: $$ --------------------- $$ | . 1 X X Y X O X . . $$ | X X O X O X O X . . $$ | X O . O . O O X . . $$ | O . O . O O X X . . $$ | O . O W O X X . . . $$ | O O O . O X X X . . . . $$ | X X O O X . . . . . . $$ | X X X X X[/go]

Click Here To Show Diagram Code: [go]$$W Now for the second test of Article 7. Is there any black play that can produce a new stone for :bt: that cannot be captured? No. None of these plays work. There is no stone that black can which is somehow prevented from being captured by white. This confirms that :bt: is dead. $$ --------------------- $$ | a 1 b c e f O X . . $$ | X X O d O g O X . . $$ | X O h O i O O X . . $$ | O j O k O O X X . . $$ | O l O W O X X . . . $$ | O O O m O X X X . . . . $$ | X X O O X . . . . . . $$ | X X X X X[/go]

------------------------
What about the other Black group?

Yes it is dead. Two moves by White would be required but the explanations to Article 7 show that groups of stones may be dead even if they cannot be captured by 1 move. Article 7 only asks whether the White player could play to capture. THERE IS NO ABILITY FOR BLACK TO PLAY. Black only has the ability to attempt to play a new stone that may try to not be captured after the group of stones under the confirmation-process are captured.

Click Here To Show Diagram Code: [go]$$W The black group :bs: is dead because it can be made to be illegal to exist on the board by :wc: and :ws:. That is, :wc: and :ws: can capture :bt: $$ --------------------- $$ | @ W X X X X O X . . $$ | # X O X O X O X . . $$ | X O . O . O O X . . $$ | O . O . O O X X . . $$ | O . O O O X X . . . $$ | O O O . O X X X . . . . $$ | X X O O X . . . . . . $$ | X X X X X[/go]

Click Here To Show Diagram Code: [go]$$W The black group :bs: when captured, as shown, cannot play a new stone that cannot be captured at any point (a-n) $$ --------------------- $$ | O O a b c d O X . . $$ | e f O g O h O X . . $$ | i O j O k O O X . . $$ | O l O m O O X X . . $$ | O n O O O X X . . . $$ | O O O . O X X X . . . . $$ | X X O O X . . . . . . $$ | X X X X X[/go]

kvasir · Post by **kvasir** » Sat Oct 02, 2021 11:28 am

CDavis7M wrote:I have no idea what you are saying if we are talking about the Japanese rules (it seems like we are) because these terms are not terms of the Japanese rules.

It would probably be best to just use the terms of the rules since they are the terms for a reason.

First of all we were talking about what ko is not about any specific rules. Secondly I was stating that we should be carful with how we think about concepts because this can easily lead us astray. For example you seem to think that if it is not found in the NHK rules then it is invalid but you would be wrong about that.

CDavis7M wrote:The test for being alive is specificaally whether or not the stones can be captured, or whether a new stone played after their capture can not be captured. It's really that simple.

This actually has nothing to do with it because we were not talking about the life and death status but what is a ko and the "pass for a particular ko" rule which we just call pass-ko because it is so nice to use names for things.

I really did add an eye to the white group hoping we wouldn't start discussing life and death, the two eyes really give away that white is alive. I am surprised that you would actually post multiple diagrams explaining me that white is alive. It is just funny

CDavis7M · Post by **CDavis7M** » Sat Oct 02, 2021 12:46 pm

kvasir wrote:First of all we were talking about what ko is not about any specific rules.

So you were discussing a rule that is not a rule? ...

kvasir wrote: Secondly I was stating that we should be carful with how we think about concepts because this can easily lead us astray. For example you seem to think that if it is not found in the NHK rules then it is invalid but you would be wrong about that.

I clearly do not think that. I just think that if its not in the Japanese Rules than its not part of the Japanese rules. That's simple.

kvasir wrote:This actually has nothing to do with it because we were not talking about the life and death status but what is a ko and the "pass for a particular ko" rule which we just call pass-ko because it is so nice to use names for things.

So you were talking about life and death confirmation (the only place pass for ko can happen) but also not talking about life and death confirmation (life and death)?

kvasir wrote:I really did add an eye to the white group hoping we wouldn't start discussing life and death, the two eyes really give away that white is alive. I am surprised that you would actually post multiple diagrams explaining me that white is alive. It is just funny

Well geez. My bad. But even worse, I can't believe people really can't read the couple of lines defining what a ko is and how pass is related to ko, because they are perfectly clear.

Also, the reason I bothered to post diagrams is because many people (including you?) here misunderstand how life and death is confirmed in the Japanese Rules. You were describing confirmation of life and death in a manner that is not allowed by the Japanese rules. If you were not talking about the Japanese rules, then your post was just vague because the topic presented in the original post is the Japanese rules.

kvasir · Post by **kvasir** » Sat Oct 02, 2021 1:31 pm

CDavis7M wrote:So you were discussing a rule that is not a rule? ...

You tell me that if I am talking about Japanese rules then I should only use terms found in the NHK rules and now you ask me this when I reply you that I was not just talking about the NHK rules.

CDavis7M wrote:Also, the reason I bothered to post diagrams is because many people (including you?) here misunderstand how life and death is confirmed in the Japanese Rules. You were describing confirmation of life and death in a manner that is not allowed by the Japanese rules. If you were not talking about the Japanese rules, then your post was just vague because the topic presented in the original post is the Japanese rules.

The diagram was just supposed to illustrate something I was saying, not actually show confirmation of life and death.

This topic is all about different types of ko bans, cycles and what not that is nowhere found in the NHK rules. There is no "no ban in double ko" rule in the NHK rules so the topic exactly matches your "if it's not in the Japanese rules than it's not" criteria.

jann · Post by **jann** » Sat Oct 02, 2021 6:19 pm

CDavis7M wrote:
jann wrote:I won't repeat what I already wrote, but one more thing: there are cases/shapes where only one side has things to play (several moves even) while the other has to pass. So "B pass, W play, B pass, W play, B pass, W pass" can sometimes be the ONLY meaningful way to finish a game.
Find it for me and I will show you why that's wrong.

The role of passes is actually one of the more clear issues. On this the text and commentary itself is reasonably clear, and contains useful hints and references (all those "exceptions", as you dismissed). In other, less obvious rule questions your only hint will be common sense and actual practice.

CDavis7M · Post by **CDavis7M** » Sat Oct 02, 2021 9:59 pm

jann wrote:The role of passes is actually one of the more clear issues.

The roll of the term "pass" is clear. But the original post is about the interpretation of J89 and J89 does not generally allow for a "pass." It allows for "着手の放棄" (move abandoned) and there appears to be confusion on the role of 着手の放棄. While 着手の放棄 might be called a pass (パス, as stated), it is not a "pass" of one's turn, but simply a declaration to stop the game and confirm life and death. Nowhere does J89 does not allow for a stone to be played after a pass (except when resuming the game of before recapturing a ko when confirmation L&D).

Maybe the players don't want to play. But confirmation of life and death can still be conducted, which is a meaningful end to the game, using the definition of 活き石 (alive stone) without any need for one player to play their own stones one after the other while their opponent passes.

==============

jann wrote:there are cases/shapes where only one side has things to play (several moves even) while the other has to pass. So "B pass, W play, B pass, W play, B pass, W pass" can sometimes be the ONLY meaningful way to finish a game.

Thank you for the 2 examples but I don't see how they require one player to pass again and again to the other player can play again and again.

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

I don't see any need to "pass the play" here. Life and death can be confirmed as is, wihtout playing or "passing your turn."

===================================

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

If the game ends in a position then that is the ending position. I don't see any need to force a different position using passes.
This situation has a ko. But this is not a situation that requires one player to pass again and again to the other player can play again and again.

Now that I think about it, this situation actually shows why it would be bad for the players to be allowed to play after a pass.

jann · Post by **jann** » Sat Oct 02, 2021 10:11 pm

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

CDavis7M wrote: I don't see any need to "pass the play" here. Life and death can be confirmed as is, wihtout playing or "passing your turn."

You seem to be unaware of this, but territory scoring rules cannot score points in sekis. So W has to actually capture single B stones in the game, while B keeps passing. Only then will the final scorable (confirmable) position reached.

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

But this is not a situation that requires one player to pass again and again to the other player can play again and again. In fact, that player should not do that.

Now that I think about it, this situation actually shows why it would be bad for the players to be allowed to play after a pass.

The above shape is a mannenko. Only W can win and fill the ko (B would die if he tried it). So W will need to capture the ko then fill it, while B keeps passing. Only then will the final scorable position reached.

(BTW this is one of the examples that prompted some historical disputes, before your approach was finally abolished and modern rules principles laid down.)

CDavis7M · Post by **CDavis7M** » Sun Oct 03, 2021 10:33 pm

jann wrote:You seem to be unaware of this, but territory scoring rules cannot score points in sekis. So W has to actually capture single B stones in the game.

First of all, this is a scorable position. Life and Death can be confirmed as I said. There is no need to pass. I did understood that white doesn't score eyes in seki, but I did miss that dead stones in seki cannot become prisoners even though dead. So thank you for highlighting the issue. Still, the Japanese rules do not allow for passing a turn during the game and there is no reason for the Japanese rules to do so. Confirmation of Life and Death allows passing and can score all situations. Maybe if the Even on the 7x3, this "problem" is practically impossible. And it's not actually a problem as the rules allow the players to easily end and resume the game to get an actual turn-pass (rather than the abandoned move, which is allows). The players do not need to pass their turn during the game.

jann wrote:The above shape is a mannenko. Only W can win and fill the ko (B would die if he tried it). So W will need to capture the ko then fill it, while B keeps passing. Only then will the final scorable position reached.

No, there is already a scorable position. White doesn't need to capture while black passes. This position is scorable according to rules on confirmation of life and death (which can use passes) without using passes in the actual game.

jann · Post by **jann** » Sun Oct 03, 2021 11:46 pm

CDavis7M wrote:And it's not actually a problem as the rules allow the players to easily end and resume the game to get an actual turn-pass (rather than the abandoned move, which is allows). The players do not need to pass their turn during the game.

I wrote this as a joke in the other topic.

Never thought you'd seriously consider N resumptions for N dead stone captures from sekis, even now...

jann wrote:The above shape is a mannenko. Only W can win and fill the ko (B would die if he tried it). So W will need to capture the ko then fill it, while B keeps passing. Only then will the final scorable position reached.
No, there is already a scorable position. White doesn't need to capture while black passes.

The first written version of the Japanese rules contained an explicit mention that in mannenkos, if neither side wants to start the ko (ie. approach and convert to a do or die step ko), the player who can win and fill the ko for seki must do so. The above position is NOT a scorable final position.

The 1989 version does not contain such explicit rule anymore since it became unnecessary. Passes (even as ko threats) now allow reaching the same final position (and the correct score, which is different after W ko capture) naturally.

CDavis7M · Post by **CDavis7M** » Mon Oct 04, 2021 8:56 am

jann wrote:
CDavis7M wrote:And it's not actually a problem as the rules allow the players to easily end and resume the game to get an actual turn-pass (rather than the abandoned move, which is allows). The players do not need to pass their turn during the game.
I wrote this as a joke in the other topic. Never thought you'd seriously consider N resumptions for N dead stone captures from sekis, even now...

It is a practically impossible situation that is easily handled by the rules if needed. There is no issue. I can't believe that you prefer to make believe rules that do not exist just because you think the game should work that way. I just read the rules and follow them. I have no obsession with working my will on them.

jann wrote:The 1989 version does not contain such explicit rule anymore since it became unnecessary. Passes (even as ko threats) now allow reaching the same final position (and the correct score, which is different after W ko capture) naturally.

Right, the rules cover this situation. Passes are allowed (required even) when confirming Life and Death. That does not mean that passes are allowed during the game.

And under the rules you are describing, it would be practically impossible for the game to have no other move that could be made during mannenko resolution other than a pass. A pass is necessary to achieve a scorable position in any practical situation.

The game allows "alternating play." That's it. You can pass to begin L&D confirmation but there is no allowance to pass before then. Anything not allowed by the rules is not allowed in the game.

jann · Post by **jann** » Mon Oct 04, 2021 9:59 am

CDavis7M wrote:Passes are allowed (required even) when confirming Life and Death. That does not mean that passes are allowed during the game.

Neither capturing dead stones from sekis, nor capturing mannenkos are possible during confirmation. These moves need to be played in actual play, while the opponent keeps passing.

it would be practically impossible for the game to have no other move that could be made during mannenko resolution other than a pass.

In territory scoring any move other than dame costs a point, and dame is not always available.

The game allows "alternating play." That's it. You can pass to begin L&D confirmation but there is no allowance to pass before then.

Although neither J49 nor J89 (something in between), wagc rules even spell the opposite out explicitly.

CDavis7M · Post by **CDavis7M** » Mon Oct 04, 2021 2:02 pm

jann wrote:Neither capturing dead stones from sekis, nor capturing mannenkos are possible during confirmation. These moves need to be played in actual play, while the opponent keeps passing.

These moves do not need to be played. There is no failure in the game or rules if this does not happen. A mannenko IS a seki regardless of whether the stone is captured or not. If capturing a stone from a seki or a mannenko is desired because of the score, the Japanese Rules allow for easy resumption of the game. It's no big deal.

If the resumption rules already provide a solution for capturing dead stones within a seki, then it is better rules design to not have additional unnecessary rules to achieve the same result.

If Life & Death confirmation already allows life/death to be determined using passing in that context (which achieves results that cannot be achieved by play), then it is better rules design to allow passing in that context and to not have a separate unnecessary allowance in other contexts. Just use the rules already available.

jann wrote:wagc rules even spell the opposite out explicitly.

It's totally fine to have a different ruleset. There is nothing terrible with passing. It's just unnecessary and allows for griefing.

jann · Post by **jann** » Mon Oct 04, 2021 8:29 pm

CDavis7M wrote:These moves do not need to be played. There is no failure in the game or rules if this does not happen. A mannenko IS a seki regardless of whether the stone is captured or not.

How mannenko should be handled is not open to any interpretation, because earlier versions of the text explicitly mentioned this as a precedent: one side must capture it and connect to make seki. (Not capturing would even make 1 point difference.)

the Japanese Rules allow for easy resumption of the game.

Resumption is not the same as directly continuing normal play, partly because whoever resumes must let the opponent move first. So if a player made a mistake of passing too early (leaving his group vulnerable after the opponent's last move), the opponent is allowed to play immediately and punish that mistake. Requesting resumption would not make that possible (player would realize and protect before, since he would get to move first).

If Life & Death confirmation already allows life/death to be determined using passing in that context (which achieves results that cannot be achieved by play), then it is better rules design to allow passing in that context and to not have a separate unnecessary allowance in other contexts. Just use the rules already available.

You are free to use "good rules design" in your own rules (if you honestly think of inconsistence like that). But with some experience you will find that in many cases "rules already available" only come in the form of indirect hints and actual practice. Japanese text doesn't spell out everything literally, you also need to read between the lines. If playing after opponent's pass is explicitly mentioned in resumption, and also explicitly mentioned in confirmation, that is strong hint that it is naturally ok in main game as well, even if the text doesn't happen to show explicit example of that too.

Life In 19x19

The "no ban in double ko" rule to solve pass-for-ko issue ?

Re: The "no ban in double ko" rule to solve pass-for-ko issu

Re: The "no ban in double ko" rule to solve pass-for-ko issu

Re: The "no ban in double ko" rule to solve pass-for-ko issu

Re: The "no ban in double ko" rule to solve pass-for-ko issu

Re: The "no ban in double ko" rule to solve pass-for-ko issu

Re: The "no ban in double ko" rule to solve pass-for-ko issu

Re: The "no ban in double ko" rule to solve pass-for-ko issu

Re: The "no ban in double ko" rule to solve pass-for-ko issu

Re: The "no ban in double ko" rule to solve pass-for-ko issu

Re: The "no ban in double ko" rule to solve pass-for-ko issu

Re: The "no ban in double ko" rule to solve pass-for-ko issu

Re: The "no ban in double ko" rule to solve pass-for-ko issu

Re: The "no ban in double ko" rule to solve pass-for-ko issu

Re: The "no ban in double ko" rule to solve pass-for-ko issu

Re: The "no ban in double ko" rule to solve pass-for-ko issu