Life In 19x19

Gérard TAILLE wrote:

Bill Spight wrote: Under Spight rules with territory scoring, one sided dame are territory.

That is exactly what I meant.

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$$ | . . O X O O O |
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$$ | X X X X X O O |
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Click Here To Show Diagram Code

[go]$$B
$$ ----------------
$$ | . O O X O O . |
$$ | X . O X O O X |
$$ | X X O X O O . |
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In this example you can see 4 points for black (4 points of territory) against 5 points for white (4 points of territory + 1 prisonner). Black has 2 one-sided dames => the result of the encore will be a black win by 1 point.

Except that under Spight territory rules we can see 2 points for the one way dame in the top left plus 2 points for the group in the bottom left = 4 points for Black minus 3 points for White on the right side.

Gérard TAILLE wrote:As far as I am concerned I like Spight rules for its simplicity. It is really a great advantage comparing to the complex japonese rule. Now for a player wanted to play in a pure territory context I imagine she will not like to take into account one-sided dames which looks really an area approach. That's life

Thank you. I am fond of them myself. But I have to admit that they have a group tax. A group tax which applies to the one way dame as well as to the surrounded points and the dead stone elsewhere on the board. If the players do not want to use a group tax, it is easy for them to adjust for it.

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When I first heard about the Segoe-Takahashi game that eventually led to the Japanese 1949 rules, I thought that the main question was about how to determine life and death. That was the focus of Ing's commentary. Much later I learned that the main focus for the Japanese at that time was whether Black was obliged to take and fill the mannenko, which was the custom, and which the referee told him to do. White, Segoe, was some 30 points ahead and if the game had been played out at temperature -1, he would have easily won. But games were not played out, and there was no concept of temperature -1 or of prisoner return until the advent of CGT, decades later. The main question boiled down to this: Is making a move a right or an obligation?

In No Pass Go it is an obligation. But that does not mean that games are played out to the bitter end. Below temperature 0 games have scores and the result may be calculated without having to play the game out. Thus, combinatorial games have a natural stopping point at or below temperature 0 when the players can agree to a final net score. The fact that Japanese games ended by agreement, even when I learned the game in the late 1960s, makes me think that Japanese Go descended from a form of No Pass Go.

Bill Spight wrote:

Gérard TAILLE wrote:

Bill Spight wrote: Under Spight rules with territory scoring, one sided dame are territory.

That is exactly what I meant.

$$B
$$ ----------------
$$ | . O O X O O . |
$$ | X . O X O O X |
$$ | X X O X O O . |
$$ | . . O X O O O |
$$ | O O O X O O O |
$$ | X X X X X O O |
$$ | . . . . X O . |
$$ -------------

Click Here To Show Diagram Code

[go]$$B
$$ ----------------
$$ | . O O X O O . |
$$ | X . O X O O X |
$$ | X X O X O O . |
$$ | . . O X O O O |
$$ | O O O X O O O |
$$ | X X X X X O O |
$$ | . . . . X O . |
$$ -------------[/go]

In this example you can see 4 points for black (4 points of territory) against 5 points for white (4 points of territory + 1 prisonner). Black has 2 one-sided dames => the result of the encore will be a black win by 1 point.

Except that under Spight territory rules we can see 2 points for the one way dame in the top left plus 2 points for the group in the bottom left = 4 points for Black minus 3 points for White on the right side.

Gérard TAILLE wrote:As far as I am concerned I like Spight rules for its simplicity. It is really a great advantage comparing to the complex japonese rule. Now for a player wanted to play in a pure territory context I imagine she will not like to take into account one-sided dames which looks really an area approach. That's life

Thank you. I am fond of them myself. But I have to admit that they have a group tax. A group tax which applies to the one way dame as well as to the surrounded points and the dead stone elsewhere on the board. If the players do not want to use a group tax, it is easy for them to adjust for it.

----

When I first heard about the Segoe-Takahashi game that eventually led to the Japanese 1949 rules, I thought that the main question was about how to determine life and death. That was the focus of Ing's commentary. Much later I learned that the main focus for the Japanese at that time was whether Black was obliged to take and fill the mannenko, which was the custom, and which the referee told him to do. White, Segoe, was some 30 points ahead and if the game had been played out at temperature -1, he would have easily won. But games were not played out, and there was no concept of temperature -1 or of prisoner return until the advent of CGT, decades later. The main question boiled down to this: Is making a move a right or an obligation?

In No Pass Go it is an obligation. But that does not mean that games are played out to the bitter end. Below temperature 0 games have scores and the result may be calculated without having to play the game out. Thus, combinatorial games have a natural stopping point at or below temperature 0 when the players can agree to a final net score. The fact that Japanese games ended by agreement, even when I learned the game in the late 1960s, makes me think that Japanese Go descended from a form of No Pass Go.

Do you know is some work has been done in the past, in order to try to identify clearly these one-sided dames in order to be able to exclude these points from the count?

Gérard TAILLE wrote:Do you know is some work has been done in the past, in order to try to identify clearly these one-sided dames in order to be able to exclude these points from the count?

I do not know of any original research into one sided dame, but I expect that they were known well over 1,000 years ago.

Bill Spight wrote:The fact that Japanese games ended by agreement, even when I learned the game in the late 1960s, makes me think that Japanese Go descended from a form of No Pass Go.

Bill, could you clarify what is meant by "ended by agreement"?

In my own games, and those I have watched, an in-person, face-to-face game usually ends in some sort of informal agreement, rather than any formal signalling with passing. One player says something like. "Well, I can't see anything else to do", and the other player responds with "Neither can I. I guess that's it". And so the game ends, and they remove the dead stones and begin counting. This happens whether they are using area scoring or territory scoring.

Or is there something else meant by "ended by agreement", that was done in Japanese games of several decades ago?

Bill Spight wrote:Whether the ko can be retaken after pass (in normal play) is not completely clear but may be guessed as passing for a ko (then retake it) is also the basis in hypothetical play.

The Japanese rule are clear. The rules only allow for a stone to be played after another stone. There is no rule allowing for a stone to be played after a pass unless the game has resumed or unless confirming life and death status of a ko.

Bill Spight wrote:This is not a defintion of resumption and thus the rule seems to me really unclear on that point (I mean retaking a ko immediatly after pass moves), even if I undersatng your guessing.

A ko may only be retaken after a pass in life and death confirmation. While the rules allow for a move to be played after a pass when resuming, they do not allow for retaking a ko that was the last move played (passes are not part of the consideration).

Bill Spight wrote: What is really the purpose of the resumption? Is it only for resolving some disagreements between the two players on the status of some group of stones, or could it be really a strategic mean to retake a ko by using a pass as a ko threat?

A ko may not be retaken. The only purpose is to resolve disagreements.

Bill Spight wrote:Hypothetical play is one way of reaching agreement about their status.

Hypothetical play is one way, but it is not the way of the Japanese Rules. The Japanese Rules confirm life and death by the definition of life and death given in the rules, which may be explained in a manner similar to "hypothetical play" but it is certainly very different from play.

Bill Spight wrote:But it is possible that the life or death of stones depends upon who plays first, and that is why the players do not agree. That is why the player who requests resumption must allow his opponent to play first. Neither player is allowed to benefit from the discussion about hypothetical play. In theory, both players could lose.

Right, the Japanese rules specifically state that both players lose.

CDavis7M wrote:

Bill Spight wrote:Whether the ko can be retaken after pass (in normal play) is not completely clear but may be guessed as passing for a ko (then retake it) is also the basis in hypothetical play.

The Japanese rule are clear. The rules only allow for a stone to be played after another stone. There is no rule allowing for a stone to be played after a pass unless the game has resumed or unless confirming life and death status of a ko.

Are you suggesting that after taking the last ko in the game, I am not allowed to fill it after my opponent has passed ?

Pio2001 wrote:

CDavis7M wrote:

Bill Spight wrote:Whether the ko can be retaken after pass (in normal play) is not completely clear but may be guessed as passing for a ko (then retake it) is also the basis in hypothetical play.

The Japanese rule are clear. The rules only allow for a stone to be played after another stone. There is no rule allowing for a stone to be played after a pass unless the game has resumed or unless confirming life and death status of a ko.

Are you suggesting that after taking the last ko in the game, I am not allowed to fill it after my opponent has passed ?

It is not allowed in "play" (before 2 passes) but it is allowed in the end of game (after 2 passes).