Japonese counting

Cassandra · **#141**

Gérard TAILLE wrote:

Is seki the expected result? I do not know but the losing player made a mistake by passing. She would have continue the game by playing the triple ko to reach a NO RESULT game. IOW the result of the confirmation phase is not relevant. In any case the potential losing player can always continue the game to reach a NO RESULT.

I think you hit the nail on the head.

This is just what I meant.

If the three ko shapes are solidly connected, and consequently only two groups involved, the (J89) result of the status-assessment of this triple-ko shape would be SEKI.
=> Probably one player would prefer "no result".

If the three ko shapes are seperated (e.g. into a double-ko and a simple ko), the J89 examples enforce the death of several groups, ruling out the possibility of SEKI.

Does this mean that a triple-ko is not a triple-ko?

Gérard TAILLE · **#142**

Cassandra wrote:

Gérard TAILLE wrote:

Is seki the expected result? I do not know but the losing player made a mistake by passing. She would have continue the game by playing the triple ko to reach a NO RESULT game. IOW the result of the confirmation phase is not relevant. In any case the potential losing player can always continue the game to reach a NO RESULT.

I think you hit the nail on the head.

This is just what I meant.

If the three ko shapes are solidly connected, and consequently only two groups involved, the (J89) result of the status-assessment of this triple-ko shape would be SEKI.
=> Probably one player would prefer "no result".

If the three ko shapes are seperated (e.g. into a double-ko and a simple ko), the J89 examples enforce the death of several groups, ruling out the possibility of SEKI.

Does this mean that a triple-ko is not a triple-ko?

Oops there are big differences betweeen a solid triple ko and the following position.

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

Assuming neither player can allow losing her big group at the top the result is not necessarily a NO RESULT as with a solid triple ko.
As you can see black as a serious advantage because black can force a NO RESULT game.
For white it is quite different because she cannot force a cycle in normal play. After:

Click Here To Show Diagram Code: [go]$$W pass pass $$ +---------------------------------------+ $$ | . O O . O . O X 1 X O . O X . . . . . | $$ | O X X O O O O X X O O O O X . . . . . | $$ | X X . X X X O X O 2 O X X X . . . . . | $$ | . . . , X O X X X O O X . . . , . . . | $$ | . . . . X O X . X O X X . . . . . . . | $$ | . . . . X O X X O X X . . . . . . . . | $$ | . . . . X O O O O . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . |[/go]

the game stops and white must resume the game to continue the game. If we assume white is not allowed to resume the game an infinite time then the game will definitly stop and the confirmation phase will take place.

In J89 you already showed that a loop can take place in this confirmation phase => white is alive => seki.
If this result is enough for black to win then it will be the result of the game. But if the seki implies a losing game for black then black will choose to play the triple ko to reach a NO RESULT.
Comparing to the solidly connected triple ko it is quite different : the player with the advantage (here black) cannot lose, the result will be either a win of this player or NO RESULT depending of the score in case of seki.

In J2003 it is quite different:

Click Here To Show Diagram Code: [go]$$B w4: ko-pass $$ +---------------------------------------+ $$ | 1 O O 5 O . O X 2 X O . O X . . . . . | $$ | O X X O O O O X X O O O O X . . . . . | $$ | X X . X X X O X O 3 O X X X . . . . . | $$ | . . . , X O X X X O O X . . . , . . . | $$ | . . . . X O X . X O X X . . . . . . . | $$ | . . . . X O X X O X X . . . . . . . . | $$ | . . . . X O O O O . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . |[/go]

Click Here To Show Diagram Code: [go]$$B $$ +---------------------------------------+ $$ | X 7 6 . O . O X O 9 O . O X . . . . . | $$ | O X X O O O O X X O O O O X . . . . . | $$ | X X . X X X O X 8 X O X X X . . . . . | $$ | . . . , X O X X X O O X . . . , . . . | $$ | . . . . X O X . X O X X . . . . . . . | $$ | . . . . X O X X O X X . . . . . . . . | $$ | . . . . X O O O O . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . |[/go]

this

for black is here allowed because after the previous :w4:

ko-pass, taking the ko at :b9:

becomes allowed!
In J2003 all the white stones are dead.

Here again we can ask yourself what is the expected result but I do not know what japonese professionals will decide.

Cassandra · **#143**

Gérard TAILLE wrote:

Comparing to the solidly connected triple ko it is quite different : the player with the advantage (here black) cannot lose, the result will be either a win of this player or NO RESULT depending of the score in case of seki.

I am happy that we agree that the types of triple-ko I mentioned are different.

Positions, which have a one-sided advantage, are usual also in J89. Therefore, it does not matter whether both sides can enforce a NO RESULT, or only one.

If Black cannot lose, as you finally concluded, the only reason left for beating the White stones to death during status-confirmation is to avoid NO RESULT (i.e. no win for Black) in the case that White would win even with this position kept as a seki.
This is exactly what I mentioned as likely motivation of the authors of J89.

But why on earth should it be mandatory for the party, which large triple-ko portion is sandwiched between opponent's groups, to win a game of Go?

Gérard TAILLE · **#144**

Cassandra wrote:

I am happy that we agree that the types of triple-ko I mentioned are different.

OC I agree with you. In addition let's look at the example 11:

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

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

In J89 the white marked are still alive because of the loop in the confirmation phase in top right corner.
In J2003 these stones are dead.
Surely it is a failure of J89 isn't it?

More generally J89 fails to handle double ko as I showed you with the example:

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

By the way, in J2003, you have two different ways for killing white stone marked:

Click Here To Show Diagram Code: [go]$$B ko-pass $$ ----------------- $$ | . X 2 X O X . | $$ | X X X O O X X | $$ | O X O O X X . | $$ | 3 O . O O X . | $$ | O O O O O X . | $$ | X X X X X X 5 | $$ | . X . . . 1 Q | $$ -----------------[/go]

Click Here To Show Diagram Code: [go]$$B ko-pass is allowed! $$ ----------------- $$ | . X . 7 O X . | $$ | X X X O O X X | $$ | 6 X O O X X . | $$ | X O . O O X . | $$ | O O O O O X . | $$ | X X X X X X X | $$ | . X . . . X . | $$ -----------------[/go]

or you can use the following barrier

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

and play

Click Here To Show Diagram Code: [go]$$B $$ ----------------- $$ | 4 X 2 X W X . | $$ | X X X W W X X | $$ | O X W W X X . | $$ | . W . W W X . | $$ | W W W W W X . | $$ | X X X X X X 3 | $$ | . X . . . 1 Q | $$ -----------------[/go]

which seems more in the spirit of J2003!

Cassandra · **#145**

Gérard TAILLE wrote:

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

In J89 the white marked are still alive because of the loop in the confirmation phase in top right corner.

Look again :razz:

J89 translation wrote:

If both these positions are present on the board, the seven white stones on the left are dead while the enclosed black and white groups on the right are both alive in double-ko seki.

Cassandra · **#146**

Gérard TAILLE wrote:

More generally J89 fails to handle double ko as I showed you with the example:

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

I told you already that example 11 is nonsens in the pedagogical sense.

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

Final position of the game.
Let us do the status confirmation for the marked White stone.

Click Here To Show Diagram Code: [go]$$B pass $$ ----------------- $$ | . X 2 X O X . | $$ | X X X O O X X | $$ | O X O O X X . | $$ | 3 O . O O X . | $$ | O O O O O X . | $$ | X X X X X X 5 | $$ | . X . . . 1 Q | $$ -----------------[/go]

This is the correct mirror for what is commented in example 11. :w4:

passes for the positon under investigation, not for lifting the ko ban in the double-ko!
White's marked stone can be captured, but no new White stone can be played.

Click Here To Show Diagram Code: [go]$$B $$ ----------------- $$ | . X 2 X O X . | $$ | X X X O O X X | $$ | O X O O X X . | $$ | . O . O O X . | $$ | O O O O O X . | $$ | X X X X X X 3 | $$ | . X . . . 1 Q | $$ -----------------[/go]

This sequence would be shorter.

Click Here To Show Diagram Code: [go]$$B pass $$ ----------------- $$ | . X . X O X . | $$ | X X X O O X X | $$ | O X O O X X . | $$ | . O . O O X . | $$ | O O O O O X . | $$ | X X X X X X 3 | $$ | . X . . . 1 Q | $$ -----------------[/go]

White might even do nothing.

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

The marked White stone is "dead".

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

Would be he same here.

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

And also here.

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

is a two-eyed-alive group, so everything inside is independent from every outside.

Cassandra · **#147**

Dear Gérard,

you were not right with your conclusions above, regarding J89, but you might have found the clue for solving examples 16 to 18 as intended.

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

Let's try to apply the example 11 commentary on problem 16...

Click Here To Show Diagram Code: [go]$$B passes for the ko at left $$ +---------------------------------------+ $$ | 1 O O . O . O X 2 X O . O X . . . . . | $$ | O X X O O O O X X O O O O X . . . . . | $$ | X X . X X X O X O 3 O X X X . . . . . | $$ | . . . , X O X X X O O X . . . , . . . | $$ | . . . . X O X . X O X X . . . . . . . | $$ | . . . . X O X X O X X . . . . . . . . | $$ | . . . . X O O O O . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . |[/go]

Click Here To Show Diagram Code: [go]$$B $$ +---------------------------------------+ $$ | X O O 5 O . O X O . O . O X . . . . . | $$ | . X X O O O O X X O O O O X . . . . . | $$ | X X . X X X O X . X O X X X . . . . . | $$ | . . . , X O X X X O O X . . . , . . . | $$ | . . . . X O X . X O X X . . . . . . . | $$ | . . . . X O X X O X X . . . . . . . . | $$ | . . . . X O O O O . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . |[/go]

Click Here To Show Diagram Code: [go]$$B $$ +---------------------------------------+ $$ | X . 6 X O . O X O . O . O X . . . . . | $$ | . X X O O O O X X O O O O X . . . . . | $$ | X X . X X X O X . X O X X X . . . . . | $$ | . . . , X O X X X O O X . . . , . . . | $$ | . . . . X O X . X O X X . . . . . . . | $$ | . . . . X O X X O X X . . . . . . . . | $$ | . . . . X O O O O . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . |[/go]

Click Here To Show Diagram Code: [go]$$B $$ +---------------------------------------+ $$ | X 7 O . O . O X O . O . O X . . . . . | $$ | . X X O O O O X X O O O O X . . . . . | $$ | X X . X X X O X . X O X X X . . . . . | $$ | . . . , X O X X X O O X . . . , . . . | $$ | . . . . X O X . X O X X . . . . . . . | $$ | . . . . X O X X O X X . . . . . . . . | $$ | . . . . X O O O O . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . |[/go]

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

Do you remember this formation at the top?
Looks a bit like example 11, doesn't it?
But example 11's "White's stones at the left are dead, and the two groups at the right are alive in double-ko seki" would not lead to the intended result of this example.

So let's continue ...

Click Here To Show Diagram Code: [go]$$Bm9 pass for double-ko $$ +---------------------------------------+ $$ | X X O 1 O 3 O X O . O . O X . . . . . | $$ | . X X O O O O X X O O O O X . . . . . | $$ | X X . X X X O X 2 X O X X X . . . . . | $$ | . . . , X O X X X O O X . . . , . . . | $$ | . . . . X O X . X O X X . . . . . . . | $$ | . . . . X O X X O X X . . . . . . . . | $$ | . . . . X O O O O . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . |[/go]

Ups, "collapse of the seki"!

+ + + + + + + + + + + + + + +

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

Would be the same here, where example 11 arises earlier as above.

Click Here To Show Diagram Code: [go]$$B passes for the ko at left $$ +---------------------------------------+ $$ | 1 O . O . O X 2 X O . O X . . . . . . | $$ | O X O O O O X X O O O O X . . . . . . | $$ | X X X X X O X O 3 O X X X . . . . . . | $$ | . . . X O X X X O O X . . . . , . . . | $$ | . . . X O X . X O X X . . . . . . . . | $$ | . . . X O X X O X X . . . . . . . . . | $$ | . . . X O O O O . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . |[/go]

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

Again a clone of example 11

Click Here To Show Diagram Code: [go]$$B passes for double-ko $$ +---------------------------------------+ $$ | X O 5 O 7 O X O . O . O X . . . . . . | $$ | . X O O O O X X O O O O X . . . . . . | $$ | X X X X X O X . X O X X X . . . . . . | $$ | . . . X O X X X O O X . . . . , . . . | $$ | . . . X O X . X O X X . . . . . . . . | $$ | . . . X O X X O X X . . . . . . . . . | $$ | . . . X O O O O . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . |[/go]

+ + + + + + + + + + + + + +

This procedure would imply that "pass-for-ko" was intended to be done in order of the ko captures.
But this cannot be really true, can it?

Gérard TAILLE · **#148**

Dear Cassandra,

Cassandra wrote:

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

Final position of the game.
Let us do the status confirmation for the marked White stone.

Click Here To Show Diagram Code: [go]$$B pass $$ ----------------- $$ | . X 2 X O X . | $$ | X X X O O X X | $$ | O X O O X X . | $$ | 3 O . O O X . | $$ | O O O O O X . | $$ | X X X X X X 5 | $$ | . X . . . 1 Q | $$ -----------------[/go]

This is the correct mirror for what is commented in example 11. :w4:

passes for the positon under investigation, not for lifting the ko ban in the double-ko!

Example 11 is not clear because on the same diagram two positions are presented and we may think they are independant positions. In that sense your are right OC => let's forget this example 11.

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

My diagram above propose only one position which is the position in which the game stopped.
For this position we need to apply the confirmation phase to get the status of all groups.
Assume I begin by analysing white groups, ignoring for the moment the status of black groups of stones.
Seeing in the rule the statement "Stones are said to be "alive" if they cannot be captured by the opponent, or ...", I begin by looking for uncapturable white groups and here is the result:

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

the marked white stones are uncapturable => they are alive.

Now I have to look for the status of the other white groups and I decide to consider the white stone in the bottom right corner.

Variation 1:

Click Here To Show Diagram Code: [go]$$B pass-for-ko created by $$ ----------------- $$ | . X 2 X W X . | $$ | X X X W W X X | $$ | O X W W X X . | $$ | 3 W . W W X . | $$ | W W W W W X . | $$ | X X X X X X 5 | $$ | . X . . . 1 O | $$ -----------------[/go]

Click Here To Show Diagram Code: [go]$$B pass-for-ko created by $$ ----------------- $$ | 8 X O . W X . | $$ | X X X W W X X | $$ | 6 X W W X X . | $$ | X W . W W X . | $$ | W W W W W X . | $$ | X X X X X X X | $$ | . X . . . X . | $$ -----------------[/go]

Click Here To Show Diagram Code: [go]$$B pass-for-ko created by $$ ----------------- $$ | O . O . W X . | $$ | . . . W W X X | $$ | O . W W X X . | $$ | . W . W W X . | $$ | W W W W W X . | $$ | X X X X X X X | $$ | . X . . . X . | $$ -----------------[/go]

and I see white has been able to put on the board new uncapturable stones in the upper left corner (remember that, at this time of the analysis I do not know which black groups may be uncapturable if not two-eyed groups).

For black, let's try another variation to try and prove the white stone in the bottom right corner is dead.

Variation 2:

Click Here To Show Diagram Code: [go]$$B $$ ----------------- $$ | . X 2 X W X . | $$ | X X X W W X X | $$ | O X W W X X . | $$ | 3 W . W W X . | $$ | W W W W W X . | $$ | X X X X X X . | $$ | . X . . . 1 O | $$ -----------------[/go]

pass-for-ko created by :b3:

pass-for-ko created by :w2:

Click Here To Show Diagram Code: [go]$$B $$ ----------------- $$ | . X O 7 W X . | $$ | X X X W W X X | $$ | 6 X W W X X . | $$ | X W . W W X . | $$ | W W W W W X . | $$ | X X X X X X . | $$ | . X . . . 1 Q | $$ -----------------[/go]

pass-for-ko created by :b7:

pass-for-ko created by :w6:

This loop can continue forever while the marked white stone in the bottom right corner is still not captured.

According to the article 7.1 the white stone in the bottom right corner is capturable but is alive.

In J89 no indenpendancies are defined between groups of stones (in J2003 we have the local-2 concept but not in J89). Indirectly the pass-for-ko rule creates a kind of independancy but it does not work very well here.

What in J89 rule can avoid the white defense above? (this defense does not work in J2003).

Cassandra · **#149**

Gérard TAILLE wrote:

What in J89 rule can avoid the white defense above? (this defense does not work in J2003).

I'm afraid nothing EXPLICITELY mentioned in the text can prevent this.
I think that this is a side-effect of the flawed special ko-ban rule that the authers of J89 were not aware of. I am sure that this special rule was designed for several application cases of triple-ko. Probably double-ko flew under the radar...

What makes things even worse: The explanations of the life-and-death examples support your assessment.

+ + + + + + + + + + + +

Example 1:

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

Status assessment for White's marked stone.

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

It can be captured.

Click Here To Show Diagram Code: [go]$$B $$ ----------------- $$ | X X X O . O . $$ | 2 X X O . O . $$ | X O O O O O . $$ | X X X , . . . $$ | . . X . . . . $$ | X X X . . . . $$ | . . . . . . .[/go]

White can recapture, so the status is still pending.

Click Here To Show Diagram Code: [go]$$B $$ ----------------- $$ | 5 4 . O . O . $$ | Q 3 . O . O . $$ | X O O O O O . $$ | X X X , . . . $$ | . . X . . . . $$ | X X X . . . . $$ | . . . . . . .[/go]

White's stone is captured for a SECOND time.

Does this mean that the J89 story ends here? Reborn but killed again?
NO!!!

Click Here To Show Diagram Code: [go]$$B $$ ----------------- $$ | X O 6 O . O . $$ | 7 X . O . O . $$ | X O O O O O . $$ | X X X , . . . $$ | . . X . . . . $$ | X X X . . . . $$ | . . . . . . .[/go]

White connects.
Black connects.

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

J89 declares the status of White's captured stone as "alive", because two uncapturable new stones could be played.
But are these stones played
-- AFTER White's stone had been captured for the first time, or
-- AFTER White's stone had been captured for the second time?

In the case of the latter, the new uncapturable stones would be irrelevant.
White's stone would be "dead".

Additionally, and this returns to your problem ...

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

... the new uncapturable stones are played at board points, where Black did NOT capture any White stone, and which were occupied by Black before.
I.e. there was NO rebirth of White's captured stone in the narrow sense.

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

If we were fond of "locality", we could swallow a sedative pill:

Everything happened inside the surrounding fencing by "two-eyed alive" groups.

But worse is to come ...

+ + + + + + + + + + + + + +

Example 4:

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

Status assessment for White's stones.

Click Here To Show Diagram Code: [go]$$B $$ +---------------------- $$ | . X 1 2 X X X O X . . $$ | X X O O O O O O X . . $$ | . O X X X X X X X . . $$ | . O X , X X . . . , . $$ | X O X X . X . . . . . $$ | X O X X X X . . . . . $$ | X O X . . . . . . . . $$ | O O X . . . . . . . . $$ | X X X . . . . . . . . $$ | . . . , . . . . . , . $$ | . . . . . . . . . . .[/go]

Black tries to capture.

Click Here To Show Diagram Code: [go]$$B $$ +---------------------- $$ | . X X O . 3 . O X . . $$ | X X O O O O O O X . . $$ | . O X X X X X X X . . $$ | 4 O X , X X . . . , . $$ | X O X X . X . . . . . $$ | X O X X X X . . . . . $$ | X O X . . . . . . . . $$ | O O X . . . . . . . . $$ | X X X . . . . . . . . $$ | . . . , . . . . . , . $$ | . . . . . . . . . . .[/go]

Click Here To Show Diagram Code: [go]$$B $$ +---------------------- $$ | . X X O 7 X 5 O X . . $$ | X X O O O O O O X . . $$ | . O X X X X X X X . . $$ | O O X , X X . . . , . $$ | . O X X . X . . . . . $$ | 6 O X X X X . . . . . $$ | . O X . . . . . . . . $$ | O O X . . . . . . . . $$ | X X X . . . . . . . . $$ | . . . , . . . . . , . $$ | . . . . . . . . . . .[/go]

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

The sequence shown in J89 ends with this final position.
But is is clear from the comment that the sequence during "play" is shown, which resolves the temporary seki.

Click Here To Show Diagram Code: [go]$$B $$ +---------------------- $$ | . X X . X X X . X . . $$ | X X . . . . . . X . . $$ | 8 O X X X X X X X . . $$ | O O X , X X . . . , . $$ | . O X X . X . . . . . $$ | O O X X X X . . . . . $$ | . O X . . . . . . . . $$ | O O X . . . . . . . . $$ | X X X . . . . . . . . $$ | . . . , . . . . . , . $$ | . . . . . . . . . . .[/go]

You will realise that NO uncapturable White stone has been played yet, AFTER White's group at the top has been captured.
Therefore, White needs another move at the left to enable J89 declaring the captured White stones "alive".

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

Again, as in example 1, NO White new uncapturable stone has been played at board point, which was occupied by White's captured stones before.
I.e. NO rebirth in the narrow sense.

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

Contrary to example 1, there is NO "locality" sedative pill available here!

White's "new uncapturable" stone is played OUTSIDE the surrounding fencing by "two-eyed alive" groups.

Cassandra · **#150**

Cassandra wrote:

By the way:

The life-and-death examples in J89 -- treating a compound of bent-four and double-ko -- do NOT cover ALL possible variations of shared double-ko formations. J89 suppresses an example like the following one -- with NESTED ko shapes.

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

To be honest, I have forgotten ("misplaced") the results of my J89-application trials with it. But for sure, at that time I did not dream of some restricting side conditions that prevent any triple-ko cycles.

However, I know that a status-assessment without any special ko-ban-rule will give interesting results (as well).

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

This nested type of a double-ko might be also missing as example 16A ...

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

And this one as example 16B ...

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

And this one as example 18B ...

There might be a reason that J89 does NOT have the SANDWICHED (i.e. inner) group of the double-ko with NESTED ko shapes.

Gérard TAILLE · **#151**

Dear Cassandra,
No one could disagree with you when you show the difficulties for J89 to apply articles 7.1 and 7.2 and reach the expected result (I mean the result expected by japonese profesionnals). A lot of other examples have been documented, especially by Robert.
The conclusion is clear : article 7.1 and 7.2 has to be completly reworded.

My view is that Robert made a very great progress by his J2003 rule, by introducing a ko-pass (instead of the pass-for-ko in J89) and by introducing the local-2 concept to create independancies between regions.
With this J2003 a lot of positions (not correctly analysed by J89) are now given the expected result with J2003.
Does it remain some issues with this J2003?
Unfortunetly my answer is yes:

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

In the position above, found by Lightvector, we should declare all white stones alive and black marked stones dead while J2003 declares a seki

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

and it is the same in this position I found myself : we should declare all white stones alive and black marked stones dead while J2003 declares a seki

I am not aware of other positions which could be an issue for J2003. Maybe Robert can tell us if such other positions have been identified.

BTW I believe I have found a way to correct J2003 on this point but I have still to make some verifications.

Cassandra · **#152**

Gérard TAILLE wrote:

Dear Cassandra,
No one could disagree with you when you show the difficulties for J89 to apply articles 7.1 and 7.2 and reach the expected result (I mean the result expected by japonese profesionnals).

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

What is your opinion about the status of White's marked group under J89?

Addit "example-11-condition" (which turned the results of examples 16 to 18 "correct"):
Ko-bans can be only lifted in the order of their appearance.

Cassandra · **#153**

Gérard TAILLE wrote:

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

In the position above, found by Lightvector, we should declare all white stones alive and black marked stones dead while J2003 declares a seki.

Quite apparently, even simple ko flew under the radar of the authors of a special rule to stop triple-ko positions with distributed ko shapes becoming "no result" during actual play (respectively "seki" in the status confirmation).
:razz:

+ + + + + + + + + + + +

By the way:
The position above is flawed, in that it belongs to the undefined crowd of unfinished positions.

It is a hanami-ko for Black, and so will not survive until the end of the game. White will have to add a move to terminate this ko fight.

Cassandra · **#154**

Gérard TAILLE wrote:

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

and it is the same in this position I found myself : we should declare all white stones alive and black marked stones dead while J2003 declares a seki.

The same principle as in my posting above applies here:
This position will not see the end of the game.

During status confirmation for the White stones, there will arise a double-ko, which is the reason for becoming this position a seki under J2003 (I suppose).

However, in a real game, this double-ko will become a source of unlimited ko threats for Black. It is very unlikely that no other ko will arise on the board.
Therefore, White would add a move in due time in a real game.

+ + + + + + + + + + + + + +

I think that this approach with unfinished and / or isolated positions has a similar problem as J89 has:

-- J89 tries to declare groups "dead", which could never be killed during actual play (especially triple-ko positions with distributed ko shapes).
(Would it be so disastrous to accept these (very rare) positions being "seki", similar to other cases that contain groups that are not of the "two-eyed-alive" type, but still cannot be captured? I.e. not using any special kind of ko-ban during status confirmation.)

-- The approach to generate "rule beasts" that contain unfinished and isolated positions tries to declare specific rulesets to be "flawed", despite we will never see such positions in the real world.
(Would it be so disastrous to accept these (very rare) positions being "abnormal during status confirmation", instead of trying to "correct" the corresponding ruleset?)

Gérard TAILLE · **#155**

Cassandra wrote:

Gérard TAILLE wrote:

Dear Cassandra,
No one could disagree with you when you show the difficulties for J89 to apply articles 7.1 and 7.2 and reach the expected result (I mean the result expected by japonese profesionnals).

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

What is your opinion about the status of White's marked group under J89?

Oops, the stones marked in your diagram form really three groups and you have to analyse them one by one

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

To me such nested ko acts like the common double ko. In J89 this type of ko prevents killing a string of stones with two liberties. In the diagram above all white stones are alive except the two marked stones which are dead:

Click Here To Show Diagram Code: [go]$$Bc pass-for-ko created by $$ +------------------------------ $$ | 1 O O . O . O X O X X . . . . $$ | O X X O O O O X O O X X . . . $$ | X X X X X X O X X O O X X . . $$ | . . X , X O X X 2 X O O X . . $$ | X X X X X O X . X O . O X . . $$ | O O O O O O X X O 3 O O X . . $$ | . . . . . O O X X O O X X . . $$ | . . . . . . O O O X X X . . . $$ | . . . . . . . . . . . . . . . $$ | . . . , . . . . . , . . . . .[/go]

Now if

pass-for-ko created by :w2:

then we have a loop and only one single white stone have been captured.
If :b5:

is played in the upper left corner then

Click Here To Show Diagram Code: [go]$$Bc pass-for-ko created by $$ +------------------------------ $$ | X O O 5 O 7 O X O X X . . . . $$ | . X X O O O O X O O X X . . . $$ | X X X X X X O X X O O X X . . $$ | . . X , X O X X O . O O X . . $$ | X X X X X O X 8 X O . O X . . $$ | O O O O O O X X 6 X O O X . . $$ | . . . . . O O X X O O X X . . $$ | . . . . . . O O O X X X . . . $$ | . . . . . . . . . . . . . . . $$ | . . . , . . . . . , . . . . .[/go]

and white will be able connect the :w8:

and create new uncapturable stones.

Gérard TAILLE · **#156**

Cassandra wrote:

Gérard TAILLE wrote:

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

In the position above, found by Lightvector, we should declare all white stones alive and black marked stones dead while J2003 declares a seki.

Quite apparently, even simple ko flew under the radar of the authors of a special rule to stop triple-ko positions with distributed ko shapes becoming "no result" during actual play (respectively "seki" in the status confirmation).
:razz:

+ + + + + + + + + + + +

By the way:
The position above is flawed, in that it belongs to the undefined crowd of unfinished positions.

It is a hanami-ko for Black, and so will not survive until the end of the game. White will have to add a move to terminate this ko fight.

You are right Cassandra this position can considered unfinished. But Lightvector proposed also a small change:

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

The marked stone has been added to the diagram. Do you still consider white has to add a move?
What is the difference? Now, in normal play, black is dead even if she starts to play and even if black has some unremovable ko threats at her disposal!
In J89 or J2008 it is still seki isn't it?

Gérard TAILLE · **#157**

Cassandra wrote:

The life-and-death examples in J89 -- treating a compound of bent-four and double-ko -- do NOT cover ALL possible variations of shared double-ko formations. J89 suppresses an example like the following one -- with NESTED ko shapes.

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

This position is quite interesting Cassandra.
Let's put J89 and J2003 aside for a moment. What is for you the expected result for japonese professionnals about the marked black stones?

Cassandra · **#158**

Gérard TAILLE wrote:

This position is quite interesting Cassandra.
Let's put J89 and J2003 aside for a moment. What is for you the expected result for japonese professionnals about the marked black stones?

I am afraid that I am unable to have a look into the mind of Japanese professional players.
But interpolating the given results of the corresponding J89 examples -- compound of bent-four and double-ko -- the "expected" result would claim all the marked stones being "dead".

Robert's J2003 will not have any problems to agree with that "expectation" (assumed that I applied these right).

However, J89 is the much more interesting environment. :razz:

I am very sure that it had a reason that J89 displays relative trivial sequences, but never a "solution" to the status assessment of the much more difficult examples.

Everyone loves "inside out" when it comes to sushi, but in J89 this nested double-ko shape (of White's envolved group) is used only on the "outside".
Try to apply J89 on this position (or the corresponding variation of example 16), and you will realise why. ;-)

RobertJasiek · **#159**

Gérard TAILLE wrote:

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

In the position above, found by Lightvector, we should declare all white stones alive and black marked stones dead while J2003 declares a seki

Unlike Cassandra, I think that we cannot just dismiss these positions as unsettled and therefore immaterial as status precedents because the position might have the colour-reversed copy on the board so that a jigo is possible. Then we still need to determine statuses.

However, I need to be convinced whether / why Japanese pros would have an unambiguous common sense on the statuses in this position. IMO, they do not. Therefore, J2003 is fine for this position.

Quote:

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

and it is the same in this position I found myself : we should declare all white stones alive and black marked stones dead while J2003 declares a seki

I lack time to check this position and the position with a three groups seki with asymmentric captuable strings carefully. ATM, I presume your analysis was correct. If so:

- Congratulations on finding these important positions!
- The position above is the only counter-example to J2003/35a with its intention to model all positions (except the flawed official examples 16-18) according to common J pro understanding if implicitly it exists for a position.
- Your seki position is more important because more basic / probably more frequent than hane-seki.

Quote:

I am not aware of other positions which could be an issue for J2003. Maybe Robert can tell us if such other positions have been identified.

None.

Earlier positions (only one?) for earlier J2003 versions until Mai 2004 with version 35/35a led to its creation. So it took 17 years for the first counter-example in 2021-08.

One serious alternative J2003 rules design was proposed but with essentially the same effect.

If J2003 ko rules shall be redesigned, ko-pass should be avoided. I do not know if it is possible while maintaining most traditional beasts.

Gérard TAILLE · **#160**

RobertJasiek wrote:

Gérard TAILLE wrote:

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

In the position above, found by Lightvector, we should declare all white stones alive and black marked stones dead while J2003 declares a seki

Unlike Cassandra, I think that we cannot just dismiss these positions as unsettled and therefore immaterial as status precedents because the position might have the colour-reversed copy on the board so that a jigo is possible. Then we still need to determine statuses.

However, I need to be convinced whether / why Japanese pros would have an unambiguous common sense on the statuses in this position. IMO, they do not. Therefore, J2003 is fine for this position.

Quote:

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

and it is the same in this position I found myself : we should declare all white stones alive and black marked stones dead while J2003 declares a seki

I lack time to check this position and the position with a three groups seki with asymmentric captuable strings carefully. ATM, I presume your analysis was correct. If so:

- Congratulations on finding these important positions!
- The position above is the only counter-example to J2003/35a with its intention to model all positions (except the flawed official examples 16-18) according to common J pro understanding if implicitly it exists for a position.
- Your seki position is more important because more basic / probably more frequent than hane-seki.

Quote:

I am not aware of other positions which could be an issue for J2003. Maybe Robert can tell us if such other positions have been identified.

None.

Earlier positions (only one?) for earlier J2003 versions until Mai 2004 with version 35/35a led to its creation. So it took 17 years for the first counter-example in 2021-08.

One serious alternative J2003 rules design was proposed but with essentially the same effect.

If J2003 ko rules shall be redesigned, ko-pass should be avoided. I do not know if it is possible while maintaining most traditional beasts.

My position above (using ko-pass concept) is certainly an issue for J2003 but let me say that my seki here under is not an issue for this rule; it is just a curiosity:

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

The marked black group on the left is dead while the marked black group on the right is alive but there are no consequences. Why? Because the big black group and the two white groups are alive with dame and that means that all the position is seki. IOW you just do not need to look for the status of the marked black groups of stones. Dead or alive will lead to the same seki result which is fine.

Japonese counting

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