Japonese counting

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Gérard TAILLE
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Re: Japonese counting

Post by Gérard TAILLE »

Cassandra wrote:
Gérard TAILLE wrote:
Click Here To Show Diagram Code
[go]$$B
$$ +--------------------+
$$ | X . O . . X . . . .
$$ | O O O O O X . . . .
$$ | X X X X X X . . . .
$$ | . . . . . . . . . . . .
$$ | . . . . . . . . . . . .[/go]
white stones are dead but black stone in the corner is dead => seki

Comparing the two diagrams above I expected a difference of one point at the maximum but here the difference is black territory against seki. It is not easy to understand the justification.
Click Here To Show Diagram Code
[go]$$B
$$ +--------------------+
$$ | a . O . 1 X . . . .
$$ | O O O O O X . . . .
$$ | X X X X X X . . . .
$$ | . . . . . . . . . . . .
$$ | . . . . . . . . . . . .[/go]
Black should have atttacked with :b1: from the outside, instead of at A from the inside.
Oops, it was not clear.
Click Here To Show Diagram Code
[go]$$B Position 1
$$ +--------------------+
$$ | . . O . . X . . . .
$$ | O O O O O X . . . .
$$ | X X X X X X . . . .
$$ | . . . . . . . . . . . .
$$ | . . . . . . . . . . . .[/go]
Click Here To Show Diagram Code
[go]$$B Position 2
$$ +--------------------+
$$ | X . O . . X . . . .
$$ | O O O O O X . . . .
$$ | X X X X X X . . . .
$$ | . . . . . . . . . . . .
$$ | . . . . . . . . . . . .[/go]
Do not consider position 2 beeing a consequence of position 1.
These two positions are only two different positions. I know this position is unfinished (like example 6) but, for consistency and as a go player I expected the result given by the confirmation phase for these two positions will be quite close but is not the case.
More genrally it is the problem of teire moves. In the rule itself as it is strictly written you can claim for a territory even if a teire move has not been played. It may not appear very logical that is the reality of the text.

Here is another example
Click Here To Show Diagram Code
[go]$$B
$$ +--------------------+
$$ | . . . X O . . .
$$ | . . . X O . . .
$$ | X X X X O . . .
$$ | O O O O O . . .
$$ | . . . . . . . .[/go]
Both player made a mistake by passing and now is the discussion for understanding the rule:
White : black stones are dead => all corner is white territory
Black : yes but you missed a teire move => you cannot claim for this territory. BTW why it could not be a black territory knowing I have also missed a teire move?

We all know that some ambiguities exist in J89 and a very strict application of the text may not be suitable.
What about missed teire moves? Surely it is not a easy question probably because the rule has not been written for unfinished positions.
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Re: Japonese counting

Post by Cassandra »

Gérard TAILLE wrote:What about missed teire moves? Surely it is not a easy question probably because the rule has not been written for unfinished positions.
Please refer to viewtopic.php?p=267274#p267274 .
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Re: Japonese counting

Post by Gérard TAILLE »

Cassandra wrote:
Gérard TAILLE wrote:What about missed teire moves? Surely it is not a easy question probably because the rule has not been written for unfinished positions.
Please refer to viewtopic.php?p=267274#p267274 .
Click Here To Show Diagram Code
[go]$$B
$$ +--------------------+
$$ | . . . X O . . .
$$ | . . . X O . . .
$$ | X X X X O . . .
$$ | O O O O O . . .
$$ | . . . . . . . .[/go]
Yes I agree but what is the conclusion in the diagram above?
White did not make the required teire move to really kill black (and black simply was not aware it could be killed) => what is the result when this teire move is discovered during confirmation phase ?
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Re: Japonese counting

Post by Cassandra »

Gérard TAILLE wrote:
Click Here To Show Diagram Code
[go]$$B
$$ +--------------------+
$$ | . . . X O . . .
$$ | . . . X O . . .
$$ | X X X X O . . .
$$ | O O O O O . . .
$$ | . . . . . . . .[/go]
Yes I agree but what is the conclusion in the diagram above?
White did not make the required teire move to really kill black (and black simply was not aware it could be killed) => what is the result when this teire move is discovered during confirmation phase ?
==> Article 13, Both Players Lose, Clause 1
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Re: Japonese counting

Post by Gérard TAILLE »

Cassandra wrote:
Gérard TAILLE wrote:
Click Here To Show Diagram Code
[go]$$B
$$ +--------------------+
$$ | . . . X O . . .
$$ | . . . X O . . .
$$ | X X X X O . . .
$$ | O O O O O . . .
$$ | . . . . . . . .[/go]
Yes I agree but what is the conclusion in the diagram above?
White did not make the required teire move to really kill black (and black simply was not aware it could be killed) => what is the result when this teire move is discovered during confirmation phase ?
==> Article 13, Both Players Lose, Clause 1
Isn't it possible that the two players will consider that "both players lose" is not a suitable result and they decide to agree on the result that will given by the referee, whathever is this decision? IOW, no disagreement => no "both players lose".
In any case, before not agreeing to a result we need first know this result don't we?
It seems my question remains : what is the result in the position above? is it really "both players lose" ?
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Re: Japonese counting

Post by Cassandra »

Gérard TAILLE wrote:
Cassandra wrote:
Gérard TAILLE wrote:
Click Here To Show Diagram Code
[go]$$B
$$ +--------------------+
$$ | . . . X O . . .
$$ | . . . X O . . .
$$ | X X X X O . . .
$$ | O O O O O . . .
$$ | . . . . . . . .[/go]
Yes I agree but what is the conclusion in the diagram above?
White did not make the required teire move to really kill black (and black simply was not aware it could be killed) => what is the result when this teire move is discovered during confirmation phase ?
==> Article 13, Both Players Lose, Clause 1
Isn't it possible that the two players will consider that "both players lose" is not a suitable result and they decide to agree on the result that will given by the referee, whathever is this decision? IOW, no disagreement => no "both players lose".
In any case, before not agreeing to a result we need first know this result don't we?
It seems my question remains : what is the result in the position above? is it really "both players lose" ?
J89 wrote:Article 13. Both players lose
1. After the game stops according to Article 9, if the players find an effective move, which would affect the result of the game, and therefore cannot agree to end the game, both players lose.
J89 wrote:Article 9. End of the game
3. If a player requests resumption of a stopped game, his opponent must oblige and has the right to play first.
:w1: If White would win the game, even if Black brought his group to life, she would request resumption (or let Black play a teire during status confirmation, to keep the matter simple).
:w2: If Black would win the game, even if White killed his group, he would request resumption (or let White play a teire during status confirmation, to keep the matter simple).

:b3: Otherwise, "both players lose" might be a better option.
The really most difficult Go problem ever: https://igohatsuyoron120.de/index.htm
Igo Hatsuyōron #120 (really solved by KataGo)
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Re: Japonese counting

Post by jann »

The problem with "both cannot agree, both lose" idea is that - however absurd, for unsettled position - confirmation does assign a status to each group. It is possible to score the board according to that, and that score will favor one side. That side will "agree to end the game" and will accept that score. So when/how can both actually lose?

I guess an implied meaning could be that a player is expected to :
  • either claim that the game is over (thus have no reason to object the opponent moving first in a resumption)
  • or request a resumption himself (allowing the opponent to move)
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Re: Japonese counting

Post by Gérard TAILLE »

L&D Example 6
Click Here To Show Diagram Code
[go]$$B
$$ +------------------------+
$$ | . O a X . O X . . O . .
$$ | X O O O X X O O O O . .
$$ | X X X X X O . . . . . .
$$ | O O O O O O . . . . . .
$$ | . . . . . . . . . . . .
$$ | . . . . . . . . . . . .[/go]
In normal play:
1) black plays at "a" => NO RESULT
2) white plays at "a" => white kill the corner but white lose the game by 0.5 point.

Let's imagine two very strong players able to resign if they lose, even with 0.5 points. What about their thinking in normal play:
Black : if I pass and white adds a move to kill the corner then I win => as black I decide to pass
White : if I pass and confirmation phase take place then I will win the game even without playing at "a" => I pass also
the game stops, white do not want to resume the game and black has to decide if she claims for resumption:
Black : white has not resigned => white thinks she will win with the confirmation phase. I do not understand because I believed that white was obliged to add a teire move => maybe we are not using the same rule ;-) ;-) ;-) If I am right I will not resume the game but if I am wrong I will resume the game.
What will be the result for the referee seeing the teire move has not been played ? The corner is white territory? The corner is seki? Both player lose?
At the end what do you do as black? You resume the game to reach NO RESULT game?
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Re: Japonese counting

Post by jann »

I think teire can always be forced by occupying dame (in resumption if necessary, doesn't matter which side first). There is no teire here since B is dead as it stands.

B will lose if does nothing, so asks for resumption and goes for draw on repetition (W cannot prevent even if going first since cannot afford pointwise).
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Re: Japonese counting

Post by Gérard TAILLE »

jann wrote:I think teire can always be forced by occupying dame (in resumption if necessary, doesn't matter which side first). There is no teire here since B is dead as it stands.

B will lose if does nothing, so asks for resumption and goes for draw on repetition (W cannot prevent even if going first since cannot afford pointwise).
BTW what is an unfinished position? It seems with this example that the number of points you can reach is not really the relevant. Maybe we have just to take account the four following possible results
1) black wins
2) white wins
3) jigo or NO RESULT (is it the same?)
4) both players lose
Can we say that a position is unfinished if one of the player would obtain a better result by playing instead of stopping the game" ?
Maybe we may add: or would obtain the same result with a better score but it is not that clear because when you are in a losing position and you resign it may be considered a finished position.
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Re: Japonese counting

Post by Gérard TAILLE »

Let's continue on this thread, Kvasir.
kvasir wrote:
Gérard TAILLE wrote: It seems not clear how you handle this famous double-ko "abuse"
Let's take a slightly different position:
Click Here To Show Diagram Code
[go]$$B
$$ | . . . . . . .
$$ | O O . . . . .
$$ | a O . . . . .
$$ | X O . . . . .
$$ | . B O O O . .
$$ | B B B B O . .
$$ | O B . B O . .
$$ | . O X O X . .
$$ | O O O O X . .
$$ | . O X X X . .
$$ | O O X . . . .
$$ | X X X . . . .
$$ | . . . . . . .[/go]
In this position, due to the liberty at "a" and the double-ko "abuse" then black marked stones become uncapturable (=> alive). How do you correct this result?

First, in step 1 of the first iteration we get that the marked stones are alive.
Click Here To Show Diagram Code
[go]$$B
$$ | . . . . . . .
$$ | O O . . . . .
$$ | . O . . . . .
$$ | X O . . . . .
$$ | . X O O O . .
$$ | X X X X O . .
$$ | O X . X O . .
$$ | . W X W X . .
$$ | W W W W X . .
$$ | . W X X X . .
$$ | W W X . . . .
$$ | X X X . . . .
$$ | . . . . . . .[/go]

The intention was that the marked stones can not be removed in the second iterations because they are marked alive in the first iteration, so now we can show that the black stones are dead in step 1 of the second iteration.
Click Here To Show Diagram Code
[go]$$W :b4: :b6: :b8: pass to not help white
$$ | . . . . . . .
$$ | O O . . . . .
$$ | 1 O . . . . .
$$ | 5 O . . . . .
$$ | 3 X O O O . .
$$ | X X X X O . .
$$ | 9 X 7 X O . .
$$ | 2 W X W X . .
$$ | W W W W X . .
$$ | . W X X X . .
$$ | W W X . . . .
$$ | X X X . . . .
$$ | . . . . . . .[/go]
Maybe we should take it to another thread, as was so kindly suggested, but I hope I am communicating my meaning.

Edit ==========
Now I realize that we get a double-ko seki because some of the black stones are marked alive in iteration 1. I am not sure this is a problem or unexpected, how about white needing to play the approach move to capture? Anyway it was a good point.
Oops a approach move seems a very big contraint.
Click Here To Show Diagram Code
[go]$$B
$$ | . . . . . . .
$$ | . . . . . . .
$$ | O O O O O O .
$$ | . . . . . O .
$$ | X X X X . O .
$$ | X . . . . O .
$$ | X O O O O O .
$$ | . B O O O . .
$$ | B B B B O . .
$$ | O B . B O . .
$$ | . O X O X . .
$$ | O O O O X . .
$$ | . O X X X . .
$$ | O O X . . . .
$$ | X X X . . . .
$$ | . . . . . . .[/go]
You cannot really force white to play all tha approach moves?

BTW did you look at the other suggestion: alternating systematically a "ko ban requiring an explicit pass-for-ko" and a "normal ko ban"?
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Re: Japonese counting

Post by kvasir »

Gérard TAILLE wrote: You cannot really force white to play all tha approach moves?
Why not? It is a capturing race, it makes sense that liberties have to be filled for the privilege of not having to fight the ko. The same thing happens if you replace the double-ko with a bent-4, you need to fill certain amount of liberties to win the capturing race.

The only problem I see is that it is quite tricky to deal with this kind of capturing races when ending a game, and it is not clear if you require N approach moves in some position that the Nihon Kiin would not require M moves instead.

If the aim is to not require the approach moves, then I have some ideas, but I don't think that is the idea with Japanese rules. Once you don't require approach moves you are actually changing something important. The Japanese rules are in my opinion meant to give a "typical" or "default" result of actual play with area scoring. For example, it is usually not possible to win large ko fights at the end of the game in area scoring, therefore Japanese rules do not allow you to come back to ko shapes that still exists after the game. If you don't require the approach moves it is akin to giving one player a free ride in the capturing race.
Gérard TAILLE wrote: BTW did you look at the other suggestion: alternating systematically a "ko ban requiring an explicit pass-for-ko" and a "normal ko ban"?
I am not sure what systems you mean, but I briefly considered some other ideas. Mostly discarded, because it would be complex or allow ko fights using ko threats during confirmation.
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Gérard TAILLE
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Re: Japonese counting

Post by Gérard TAILLE »

How works "alternating ko ban" with double ko?
Click Here To Show Diagram Code
[go]$$B
$$ +-------------------
$$ . . . O X O . O . |
$$ . . . O X X O O O |
$$ . . . O X . X O X |
$$ . . . O X X X X . |
$$ . . . O O O O X X |
$$ . . . . . . O O O |
$$ . . . . . . . . . |
$$ . . . . . . . . . |[/go]
Click Here To Show Diagram Code
[go]$$B
$$ +-------------------
$$ . . . O X T 1 O . |
$$ . . . O X X O O O |
$$ . . . O X . X O X |
$$ . . . O X X X X . |
$$ . . . O O O O X X |
$$ . . . . . . O O O |
$$ . . . . . . . . . |
$$ . . . . . . . . . |[/go]
after :b1: white needs a pass-for-ko to play at :wt:
Click Here To Show Diagram Code
[go]$$B
$$ +-------------------
$$ . . . O X T 1 O . |
$$ . . . O X X O O O |
$$ . . . O X . X O T |
$$ . . . O X X X X 2 |
$$ . . . O O O O X X |
$$ . . . . . . O O O |
$$ . . . . . . . . . |
$$ . . . . . . . . . |[/go]
after :w2: white and black needs a pass-for-ko to retake the ko by :wt: or :bt:
Click Here To Show Diagram Code
[go]$$B black :b3: pass for ko at :w2:
$$ +-------------------
$$ . . . O X T X O . |
$$ . . . O X X O O O |
$$ . . . O X . X O . |
$$ . . . O X X X X O |
$$ . . . O O O O X X |
$$ . . . . . . O O O |
$$ . . . . . . . . . |
$$ . . . . . . . . . |[/go]
Now black is able to retake the ko but white not
Click Here To Show Diagram Code
[go]$$W white :w4: pass for ko at :b1:
$$ +-------------------
$$ . . . O X . X O . |
$$ . . . O X X O O O |
$$ . . . O X . X O . |
$$ . . . O X X X X O |
$$ . . . O O O O X X |
$$ . . . . . . O O O |
$$ . . . . . . . . . |
$$ . . . . . . . . . |[/go]
Now black and white are able to retake their ko
Click Here To Show Diagram Code
[go]$$B
$$ +-------------------
$$ . . . O X . X O . |
$$ . . . O X X O O O |
$$ . . . O X . X O 5 |
$$ . . . O X X X X T |
$$ . . . O O O O X X |
$$ . . . . . . O O O |
$$ . . . . . . . . . |
$$ . . . . . . . . . |[/go]
after :b5: white needs a pass-for-ko to play at :wt:
Click Here To Show Diagram Code
[go]$$B
$$ +-------------------
$$ . . . O X 6 T O . |
$$ . . . O X X O O O |
$$ . . . O X . X O X |
$$ . . . O X X X X T |
$$ . . . O O O O X X |
$$ . . . . . . O O O |
$$ . . . . . . . . . |
$$ . . . . . . . . . |[/go]
after :w6: white and black needs a pass-for-ko to retake the ko by :wt: or :bt:
Click Here To Show Diagram Code
[go]$$B :b7: pass-for-ko :w8: pass-for-ko
$$ +-------------------
$$ . . . O X O . O . |
$$ . . . O X X O O O |
$$ . . . O X . X O X |
$$ . . . O X X X X . |
$$ . . . O O O O X X |
$$ . . . . . . O O O |
$$ . . . . . . . . . |
$$ . . . . . . . . . |[/go]
this loop on 8 moves is very known.
But now is the difference. Because all ko have already used the pass-for-ko then now, the normal ko ban has to be used.
Click Here To Show Diagram Code
[go]$$B :b11: pass
$$ +-------------------
$$ . . . O X O 9 O . |
$$ . . . O X X O O O |
$$ . . . O X . X O X |
$$ . . . O X X X X 0 |
$$ . . . O O O O X X |
$$ . . . . . . O O O |
$$ . . . . . . . . . |
$$ . . . . . . . . . |[/go]
In this last diagram :b9: and :w10: are normal ko => :b11: is a normal pass allowing white to play :w12: elsewhere (=> the loop has really been broken).
Click Here To Show Diagram Code
[go]$$Bm11 :w12: elsewhere
$$ +-------------------
$$ . . . O X 4 X O . |
$$ . . . O X X O O O |
$$ . . . O X . X O 3 |
$$ . . . O X X X X O |
$$ . . . O O O O X X |
$$ . . . . . . O O O |
$$ . . . . . . . . . |
$$ . . . . . . . . . |[/go]
After :b13: :w14: then black :b15: will be again a normal pass allowing white to play :w16: elsewhere.

After all that we return to the very beginning with the use of pass-for-ko etc.
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Gérard TAILLE
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Re: Japonese counting

Post by Gérard TAILLE »

kvasir wrote:
Gérard TAILLE wrote: You cannot really force white to play all tha approach moves?
Why not? It is a capturing race, it makes sense that liberties have to be filled for the privilege of not having to fight the ko. The same thing happens if you replace the double-ko with a bent-4, you need to fill certain amount of liberties to win the capturing race.

The only problem I see is that it is quite tricky to deal with this kind of capturing races when ending a game, and it is not clear if you require N approach moves in some position that the Nihon Kiin would not require M moves instead.

If the aim is to not require the approach moves, then I have some ideas, but I don't think that is the idea with Japanese rules. Once you don't require approach moves you are actually changing something important. The Japanese rules are in my opinion meant to give a "typical" or "default" result of actual play with area scoring. For example, it is usually not possible to win large ko fights at the end of the game in area scoring, therefore Japanese rules do not allow you to come back to ko shapes that still exists after the game. If you don't require the approach moves it is akin to giving one player a free ride in the capturing race.
Gérard TAILLE wrote: BTW did you look at the other suggestion: alternating systematically a "ko ban requiring an explicit pass-for-ko" and a "normal ko ban"?
I am not sure what systems you mean, but I briefly considered some other ideas. Mostly discarded, because it would be complex or allow ko fights using ko threats during confirmation.
It seems there is here some misunderstanding. White has an eye and black has not => it is not a capturing race and black is expected to be dead without the need for white to add a move.
I tried in another post to clarify what means "alterning ko ban".
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Re: Japonese counting

Post by Gérard TAILLE »

jann wrote:
Gérard TAILLE wrote:
jann wrote:This is a longstanding question in J89 which has two possible answers:
  1. Maybe passing for each ko is only required once for each player (see here)
  2. Or the problem was overlooked by J89 authors, and will be fixed in the future (with some hack like requiring a normal pass of either player before passing for a ko a second time)
1)
If you use "pass once per ko" then black can pass immediatly and wins the game because the two white marked stones are dead in the confirmation phase

2)
Click Here To Show Diagram Code
[go]$$B
$$ +---------------------–-
$$ | 2 X X O X O . . . O X O . O . |
$$ | X O 1 O X O . . . O X X O O O |
$$ | O O X X X O . . . O X . X O X |
$$ | O X X O O O . . . O X X X X . |
$$ | . O X O . . . . . O O O O X X |
$$ | . O X O . . . . . . . . O O O |
$$ | O X X O . . . . . . . . . . . |
$$ | O O O O . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . |[/go]
without using "pass once per ko", in order to win, black must continue at least one move.
After :b1: :w2: then black passes and wins the game.
Nice position, thank you. Even if harmless here since the result is the same (B can force the reinforcement with the same play either way), this does show a case where the attacker might need to play the same ko twice in confirmation.
Alternating systematically a "ko ban requiring an explicit pass-for-ko" and a "normal ko ban" seems to resolve the problem.
That idea sounds more complicated and conceptually less sound than my #2 alternative above. Anyway, the Nihon Ki-in is probably aware of the problem by now and will choose an official solution in their next version.
I agree that the idea may appear complicated but it is only a theoritical complexity. In practice it is really very simple. The idea is only to break the loop in double ko and the associated two pass-for-ko.
In practice you have only to know that pass-for-ko applies to all ko except for double ko where normal ko ban is used. In addition I doubt you will often meet a position like the one I found. Maybe another wording may be found (to avoid a loop made only of ko and pass-for-ko) to show it is not that complex, but I am not a expert in wording ;-)
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