Life In 19x19

Jhyn wrote:

Bill Spight wrote:At this point Black has the move but does not wish to play, even though he has one more stone on the board than White. (As it happens, White does not want to play, either; but I could have easily contrived a position where White would have had fewer stones on the board than Black but more plays.)

Your remark is very clear and I realise I misunderstood the previous post. Today I had another idea. If we allow another legal move which is giving back a prisoner to your opponent, does no-pass go becomes the same as most-stones go with group tax? (maybe disregarding some final ko situations)

Was there ever a ruleset allowing this? Of course it is inspired by the idea of pass stone.

No pass go with prisoner return yields territory scoring with a group tax. Professor Berlekamp demonstrated that over 20 years ago. As it turns out, the oldest existing game records that are scored seem to use territory scoring with a group tax.

Bill Spight wrote:
No pass go with prisoner return yields territory scoring with a group tax. Professor Berlekamp demonstrated that over 20 years ago. As it turns out, the oldest existing game records that are scored seem to use territory scoring with a group tax.

So even under that idea, wouldn't it be relevant whether the amount of dame left over at the end of the game is an even or odd number?

Dames are small.

Matti wrote:Dames are small.

Yes, but there are smaller plays.

Joelnelsonb wrote:

Bill Spight wrote:
No pass go with prisoner return yields territory scoring with a group tax. Professor Berlekamp demonstrated that over 20 years ago. As it turns out, the oldest existing game records that are scored seem to use territory scoring with a group tax.

So even under that idea, wouldn't it be relevant whether the amount of dame left over at the end of the game is an even or odd number?

First, let me clarify what I said about Professor Berlekamp. He did not, I think, mean to produce a set of rules with a group tax. In fact, he added an encore with immortal stones to eliminate it.

Now, on to dame in no pass go with prisoner return.

Click Here To Show Diagram Code

[go]$$W Odd or even
$$ --------------------
$$ . O . . X . O . . X .
$$ . O X X X . O O O X .
$$ . O O X . O O X X X .
$$ . . O X X X X O X . .
$$ . . O O O O O O X . .[/go]

No pass go with prisoner return. 19x19 board. Net territory plus prisoners and dead stones = 0. Only dame left otherwise. No other seki.

White to play.

The key is to realize that the number of dame elsewhere is odd.

Click Here To Show Diagram Code

[go]$$W White gets the last dame
$$ --------------------
$$ . O 2 . X 3 O . 1 X .
$$ . O X X X 4 O O O X .
$$ . O O X . O O X X X .
$$ . . O X X X X O X . .
$$ . . O O O O O O X . .[/go]

fills a dame elsewhere.

The remaining dame after are even, so White gets the last dame. Zero is a second player win, and Black will play first. White wins.

Note that the local eyes are not territory, as they are necessary for life. Also note that the remaining local neutral point is not dame in no pass go, since neither player can afford to fill it. It is also necessary for life. The fact that it remains unfilled changes the parity of the board, which is why White gets the last dame when the territory score is even.

Click Here To Show Diagram Code

[go]$$W Failure
$$ --------------------
$$ . O 1 3 X 5 O 4 2 X .
$$ . O X X X . O O O X .
$$ . O O X . O O X X X .
$$ . . O X X X X O X . .
$$ . . O O O O O O X . .[/go]

After there are two neutral points left that are necessary for life. Black gets the last dame elsewhere and wins.

So yes, there are cases in which getting the last dame affects best play.

But do we want the dame to matter?

Consider this position.

Click Here To Show Diagram Code

[go]$$B Black to play
$$ ------------
$$ . O C C X .
$$ . O X X X .
$$ . O C X . .
$$ . O O X X X[/go]

All stones are alive. The only points of interest, including dame, are the marked points. Black to play.

Click Here To Show Diagram Code

[go]$$B Black to play
$$ ------------
$$ . O 1 . X .
$$ . O X X X .
$$ . O 2 X . .
$$ . O O X X X[/go]

This play seems obvious. In the marked region Black gets one point of territory while White gets the last move. The net local area score is also one point for Black.

Click Here To Show Diagram Code

[go]$$B Variation
$$ ------------
$$ . O 3 1 X .
$$ . O X X X .
$$ . O 2 X . .
$$ . O O X X X[/go]

In this variation the local territory result is 0, but the local area result is still one point for Black. There are those, myself included, who do not like the idea that Black can get away with .

Now, to use the language of Berlekamp and Wolfe's Mathematical Go: Chilling gets the Last Point, if there are no kos, we may consider territory scoring to be a chilled form of area scoring. (See http://senseis.xmp.net/?Chilling .) Correct play in the chilled form is also correct in the unchilled form, but not vice versa. (Note that ko-less Japanese go is not a chilled form of ko-less Chinese weiqi, because of the treatment of Japanese seki. Other forms of territory go, such as Lasker-Maas rules and Spight rules, are. ) The condition of no kos is not as stringent as it might appear. If the ko is resolved early enough, then correct play under the chilled for will still be correct under the unchilled form. The chilled form is usually more stringent than the unchilled form, because there are plays that may be OK under the unchilled form that are mistakes under the chilled form. As this example shows. Berlekamp and Wolfe chill territory scoring, for an even more stringent form of go which they call chilled go. They do this by putting a one point tax on a board play.

Click Here To Show Diagram Code

[go]$$B Half point
$$ ------------
$$ . O . . X .
$$ . O X X X .
$$ . O . X . .
$$ . O O X X X[/go]

In chilled go neither player will wish to play, and the local region is scored as 0.5 point for Black.

Bill Spight wrote:But do we want the dame to matter?

Consider this position.

$$B Black to play
$$ ------------
$$ . O C C X .
$$ . O X X X .
$$ . O C X . .
$$ . O O X X X

Click Here To Show Diagram Code

[go]$$B Black to play
$$ ------------
$$ . O C C X .
$$ . O X X X .
$$ . O C X . .
$$ . O O X X X[/go]

All stones are alive. The only points of interest, including dame, are the marked points. Black to play.

$$B Black to play
$$ ------------
$$ . O 1 . X .
$$ . O X X X .
$$ . O 2 X . .
$$ . O O X X X

Click Here To Show Diagram Code

[go]$$B Black to play
$$ ------------
$$ . O 1 . X .
$$ . O X X X .
$$ . O 2 X . .
$$ . O O X X X[/go]

This play seems obvious. In the marked region Black gets one point of territory while White gets the last move. The net local area score is also one point for Black.

$$B Variation
$$ ------------
$$ . O 3 1 X .
$$ . O X X X .
$$ . O 2 X . .
$$ . O O X X X

Click Here To Show Diagram Code

[go]$$B Variation
$$ ------------
$$ . O 3 1 X .
$$ . O X X X .
$$ . O 2 X . .
$$ . O O X X X[/go]

In this variation the local territory result is 0, but the local area result is still one point for Black. There are those, myself included, who do not like the idea that Black can get away with .

At the same time, though, black is clearly giving up sente with in the variation. Not only that, but white can treat and as miai and move on right away to another part of the board, if there are other points. Effectively black has taken, using area counting, 2 points in two moves rather than 2 points in one move.

Now, it may not matter if this part of the board is the last one to be played on, of course, but that's not to say it doesn't matter most of the time. To some degree, I think this displays a bias towards the result of territory scoring over area scoring. You could just as well come up with examples where black makes the same number of points via territory scoring for two different moves while one of the moves is clearly better than the other in terms of being able to play more or fewer dame later, or is able to do it in sente one way and gote another.

skydyr wrote:

Bill Spight wrote:But do we want the dame to matter?

Consider this position.

$$B Black to play
$$ ------------
$$ . O C C X .
$$ . O X X X .
$$ . O C X . .
$$ . O O X X X

Click Here To Show Diagram Code

[go]$$B Black to play
$$ ------------
$$ . O C C X .
$$ . O X X X .
$$ . O C X . .
$$ . O O X X X[/go]

All stones are alive. The only points of interest, including dame, are the marked points. Black to play.

$$B Black to play
$$ ------------
$$ . O 1 . X .
$$ . O X X X .
$$ . O 2 X . .
$$ . O O X X X

Click Here To Show Diagram Code

[go]$$B Black to play
$$ ------------
$$ . O 1 . X .
$$ . O X X X .
$$ . O 2 X . .
$$ . O O X X X[/go]

This play seems obvious. In the marked region Black gets one point of territory while White gets the last move. The net local area score is also one point for Black.

$$B Variation
$$ ------------
$$ . O 3 1 X .
$$ . O X X X .
$$ . O 2 X . .
$$ . O O X X X

Click Here To Show Diagram Code

[go]$$B Variation
$$ ------------
$$ . O 3 1 X .
$$ . O X X X .
$$ . O 2 X . .
$$ . O O X X X[/go]

In this variation the local territory result is 0, but the local area result is still one point for Black. There are those, myself included, who do not like the idea that Black can get away with .

At the same time, though, black is clearly giving up sente with in the variation. Not only that, but white can treat and as miai and move on right away to another part of the board, if there are other points. Effectively black has taken, using area counting, 2 points in two moves rather than 2 points in one move.

That's why I said that the only points of interest were the marked points. I meant for the whole board. Guess that was not clear.

Now, it may not matter if this part of the board is the last one to be played on, of course, but that's not to say it doesn't matter most of the time. To some degree, I think this displays a bias towards the result of territory scoring over area scoring.

Actually, I am a proponent of Button Go (or Double Button Go), both of which integrate area and territory scoring.

You could just as well come up with examples where black makes the same number of points via territory scoring for two different moves while one of the moves is clearly better than the other in terms of being able to play more or fewer dame later, or is able to do it in sente one way and gote another.

Not sure what you are proposing. Without ko, there are no sequences of play that are incorrect by area scoring but correct by Lasker-Maas or Spight territory rules.

Joelnelsonb wrote:Why on earth is this not the standard way to play Go?

Using stone scoring, the games clearly divide themselves into two parts : the strategic part, where each move can change the outcome, and the filling part, that starts when modern players pass, and where the moves have no meaning anymore.
Playing out the second part is so long, so boring and so meaningless that it was decided that the game would end when the first part is over. Each player is then awarded the number of intersections that he or she conquered. This is area scoring.
Then, territory scoring is a convenient trick allowing not to count the stones.

Thus, for all practical purposes, to count the territory is the most convenient way to play go everyday, as far as players are concerned. This is why it has been the most widespread method.

Why it didn't become the universal method is a long story.

To begin with, the first official complete ruleset published (the japanese rule of 1949) tried to conciliate territory scoring with the traditions in use, such as the filling of teire points (implicit connections after the filling of the dame), and to regroup all the precedents concerning unsolved ko after the two players have passed.
Unfortunately the result was not a success. The rule, dozens of pages long, is much too long to be used for teaching and requires very tedious studying from tournament organizers. Today, it is nearly impossible to program it into a software, and in 1959, it could not prevent an undecided game to happen between Go Seigen and Takagawa Shukaku.
A striking consequence is that today, books introducing the game of go usually don't feature the rule of the game anywhere !

In 1975, the Chinese came with another official rule, using area scoring, this time. Much shorter, it can easily be taught to beginners, it is convenient for tournament organizers and programmers, and it can leave no game undecided. But for everyday use, it is much less convenient : the players must count all the stones.

In 1991, the AGA rule combined the simplicity of the chinese rule with the convenience of territory counting, in exchange for just a little effort from the players : to hand a prisoner each time thay pass.
This progress seem to seduce, and spreads slowly : a similar rule was adopted in 1994 in France, then in 2008 in United Kingdom, and this year it was used in the European Go Congress.

When will we have a unique worldwide rule of go ?

Pio2001 wrote:To begin with, the first official complete ruleset published (the japanese rule of 1949) tried to conciliate territory scoring with the traditions in use, such as the filling of teire points (implicit connections after the filling of the dame), and to regroup all the precedents concerning unsolved ko after the two players have passed.
Unfortunately the result was not a success. The rule, dozens of pages long, is much too long to be used for teaching and requires very tedious studying from tournament organizers. Today, it is nearly impossible to program it into a software, and in 1959, it could not prevent an undecided game to happen between Go Seigen and Takagawa Shukaku.

The Nihon Kiin 1989 rules are too ambiguous to be programmed, IMO.

As for the rules dispute between Go Seigen and Takagawa, at the time Go was not a member of the Nihon Kiin and had not agreed to use those rules, as Takagawa had assumed. The 1949 rules were clear that Go had to fill the final ko in the game continuation that was not played out, as both players had read it out. It was the failure to agree on the rules before the game that created the problem.

Edit: Some reports of that dispute are misleading. They say that the rules would have forced Go Seigen to protect against a ko that he would have won. Yes, he would have won it, but the point was that he would have had to fill it. The extra move to fill it would have come to the same thing as making a move to prevent it. Go Seigen argued that he would not have had to fill it, because there would have been no dame left at that point.

Joelnelsonb wrote:So this may have been thought of and talked about already but I have never heard of it. I suggest that a player ought to lose 2 points for each independent group he/she has on the board.

Indeed, it is an interesting idea, and congratulations for having come up with it on your own. As you have discovered, it is an old idea, but that does not diminish your accomplishment.

I want to thank you because I had always associated the group tax with stone scoring without giving it much thought. I knew about its association with no pass go and territory scoring long before I learned that ancient territory scoring had a group tax. Your question made me examine why stone scoring had a group tax. It is a mystery.

Thank you, Bill

As for my question about why we don't commonly see this in modern Go: I'm not so much asking why it is that people prefer to play a certain way but rather I was wondering if there is another theoretical explanation for the core objective of the game that makes group tax unnecessary or even not make sense.

Joelnelsonb wrote: As for my question about why we don't commonly see this in modern Go: I'm not so much asking why it is that people prefer to play a certain way but rather I was wondering if there is another theoretical explanation for the core objective of the game that makes group tax unnecessary or even not make sense.

It makes scoring more complicated. It's much easier to count territory after filling prisoners and leave it at that.

We get enough tax in the rest of the world. We don't need group taxes

Joelnelsonb wrote:I was wondering if there is another theoretical explanation for the core objective of the game that makes group tax unnecessary or even not make sense.

Rules are arbitrary. They don't need justification. Which ones are better is all a matter of taste, convenience, beauty etc.

Go is a game about shapes. Having area as a goal is also a matter of shape.
Having stones as a goal would also be a matter of numbers. I prefer shapes to numbers.

I don't like territory counting because of the "prisoner tax". I always think about my score in area counting, even when I play under japanese rules. My points appear as group of intersections laying on the goban. It's purely visual.

I must admit that it causes me some trouble when I practice exercises about yose : the "area" swing value of a given move can be very different from its "territory" swing value, because the number of black and white stones played locally is not always the same.

I think that one of the main problems with group tax is defining what a group is. "A group" may seem like a simple concept, but it is actually quite hard to define it precisely. You might want to post a good definition of a group before going further with your group tax idea.