Yesterday's rule dispute in Korea

[Bill Spight]

Hi Bill,
I've had a look at area button go. I've tried to see what would be the outcome of normal even games.

I've found that for games ending normally with Black or White making the last board move, and also for games ending with Black or White filling a ko playing twice in a row (the opponent then takes the button), the result of area button go was the same as territory scoring with 6.5 points komi.

Is it correct so far ?

Right.

I think the answer is No. Isn't Pio2001 asking the situation that a player is holding a half-point ko while filling in all the shared liberties?

Well, he said, "ending with Black or White filling a ko playing twice in a row (the opponent then takes the button" To me that means that the button is taken after the ko is filled (won). I don't know what he means by playing twice in a row, though. OC, he can explain what he meant.

[Pio2001]

Here are 4 standard situations, with the score in territory counting (komi 6.5), area counting (komi 7.5) and button go counting (komi 7) :
-Black and White alternate plays on the board and Black plays the last move on the board
-Black and White alternate plays on the board and White plays the last move on the board
-Black plays the two last moves on the board
-White plays the two last moves on the board



In the two cases with perfect alternation, the button go gives the same score as territory counting with komi 6.5.
In the case White plays last, the winner may depend on the style (area vs territory), because the komi is different.
In the two cases with the same player making the two last moves on the board, the score is different between button go (komi 7) and territory scoring (komi 6.5), but the winner is the same thanks to the parity.

It follows that if there is an odd number of neutral intersections in seki (parity is reversed) and if the same player plays the two last moves on the board, the winner may be different under territory scoring with komi 6.5 and button go with komi 7.

[Pio2001]

I have added the results for territory button go. They are the same as area button go.



So, if I summarize button go :

It is an area + button rule set
The best strategy is most of the times to play as if the score was japanese territory without button (common exceptions : if the last two moves consist in capturing in a ko and filling the ko and ((the handicap is even and different from zero, and the number of neutral intersection is even) or (the handicap is zero or odd, and the number of neutral intersections is odd))),
Pass stones may be used, under condition that a button stone is given in addition to the pass stones, and that if the players who took the button is the second one to pass when both players pass in a row, he or she doesn't hand a pass stone.

If I understand properly, we use nearly-pass stones (plus a button stone) and add them to the "apparent" territory in order to get the area, then we add the button to that area, which in turn tells us who's got the most "true" territory.



Unless a straightforward equivalence with territory or area can be clearly explained, I'm afraid that it doesn't meet my second requirement :

2-The rules of play should be translated and published by national federations worldwide, and referees should be able to use these translations and score games in any tournament without dispute.

[RobertJasiek]

The Korean 2016 Rules are also available as an HTML page:

http://home.snafu.de/jasiek/k2016.html

[jaeup]

I think your summary that the winner usually doesn't change at 6.5 komi is correct. I was mentioning that the score changes if you successfully perform "holding half-point ko until the end" strategy. Also, the komi of button go can be anything, and there is no reason to only assume even+0.5 komi for the analysis. (though adopting 6.5 komi for area scoring is one major motivation of it)

In addition, if something like two-stage half-point ko occurs, still the strategy can change the winner even at 6.5 komi. It is probably more likely to happen than the case of half-point ko plus a seki with odd shared liberties. Of course, one should not forget that territory in seki makes additional inevitable changes.

2-The rules of play should be translated and published by national federations worldwide, and referees should be able to use these translations and score games in any tournament without dispute.

Why? Once we decide to adopt it. It is quite easy to apply. Actually, I don't think we need to use the physical button. All we need to do is to introduce the pass stone, and make sure the opponent of the first passer to make the last pass. All the processes are easy and automatic, and after a few practices, you won't even need the referee to help you. Well, understanding the meaning of it takes more time, but the fact that they are counting the territory in the end, and 95% of the case it reproduces the traditional territory scoring will lower the psychological barrier for players to accept it.

[Pio2001]

The point that I find strange in button go is not its complications. In fact, I think that button go is ok with requirement 1 : novice players can follow the instructions without problems and score their game (maybe it would be better to remove the life and death consideration, like in the french rule, but that's not a problem).

What bothers me is that it is neither an area rule, nor a territory rule. Its true meaning is that it is an "area plus button" rule.

Practically, I am completely lost in front of a question like "should I take the ko or the button" ? The ko is said to be worth 1/3 of a point, and the button 1/2. So I should rather take the button. It is worth more.
But wait, the core rule is area, so the dame are all worth 1 point, and the ko is more like 1 + 1/3, so I should rather take the ko instead of the button.
But wait, all these are approximation, I'd better read the sequences to be sure. But, OMG, should I count territory + 6.5 komi + pass stones, or area + button ?

But maybe my point of view is biased to begin with, because I must confess that I have always loved area scoring and hated territory scoring.
I must admit that it might explain my reluctance in front of button go, or even my inability to understand its merits.

For me, area is something that can be seen on the board. Territory can't, because territory actually means territory plus prisoners plus dead stones.

[Pio2001]

By the way, in my sgf, I can see that in all cases that I have considered, button go is equivalent to territory scoring, but with one point of territory inside the ko, if it had been left open !

Wouldn't it be easier then to use the Simplified Japanese Rules ? If I understand them properly, they also grant one point of territory inside the last ko, if it stays open, and they look quite correct to me, I mean, compared to the Japanese 1989 or Japanese 1949 rules.

[RobertJasiek]

Under the Simplified Japanese Rules for one basic endgame ko stone remaining unconnected, if its defender starts the analysis by connecting it, it is independently alive and its empty intersection territory. If the attacker starts the analysis and wins the ko fight, the ko stone is not independently alive and the empty intersection not territory.

[Bill Spight]

I have added the results for territory button go. They are the same as area button go.

Right.

So, if I summarize button go :

It is an area + button rule set

It is a hybrid of area and territory rules. The score is typically the same as that by a form of territory scoring, but area rules allow questions of life and death and kos and superkos after the last dame has been filled to be settled by play.

The easiest way to implement button go is by adding a token worth ½ pt. to area rules. Implementing it via territory rules involves passing prisoners between the players.

If I understand properly, we use nearly-pass stones (plus a button stone) and add them to the "apparent" territory in order to get the area, then we add the button to that area, which in turn tells us who's got the most "true" territory.

This sounds confusing to me.

Unless a straightforward equivalence with territory or area can be clearly explained, I'm afraid that it doesn't meet my second requirement :

I am not sure what you are asking for. You have verified the equivalence of button go by area and territory scoring for typical situations. Do you want a more rigorous explanation? Or are you asking for something else?

Several years ago on the ancestor of this site I posted a fairly extensive treatment of button go, covering a variety of situations. Unfortunately, those notes got clobbered in the transition and are unrecoverable.

On the assumption that you want an explanation of why area button go and territory button go produce the same results, here is a start.

What is the basic difference between territory and area scoring? Black plays first and if Black gets the last board play at the dame stage, she will get one more point by area scoring than by territory scoring. Depending on other differences between the rules, such as counting territory in seki or not, and different ko or superko rules, there may be other differences, but this is the basic one.

Is there a way of modifying area scoring so that it does not matter who gets the last dame? Yes, there is. Each dame gains 1 point, so adding a play that is worth ½ of that, i.e., ½ pt., will do the trick. So let there be a token worth ½ pt. that a player can take. For instance, suppose that Black is to play when all that is left are dame. Then Black will gain ½ pt., no matter who gets the last dame. If White gets the last dame, so that each play has gotten the same number, Black will take the token (button) and gain ½ pt. If Black gets the last dame, and has gained 1 pt. against White, White takes the button, reducing Black's gain to ½ pt. So the area result will be the territory score + ½ pt. for Black.

What if we use territory scoring? AGA rules do that using pass stones. In that case the button is worth -½ pt., since a play by territory scoring gains 1 pt. less than by area scoring. Can we simplify that method? Yes, we can. Herman Hiddema came up with the idea of adding a second button. At first, that sounds like an additional complication, but in the end it allows us to simplify.

At the end of the game by AGA territory scoring, the players pass and each pass costs 1 pt. The current AGA rules require White to make the last pass. Is there a way to modify the rules so that it does not matter who makes the last pass? That would allow us to do away with the last pass by White rule, which is still puzzling to some players, and even objectionable to some, and is a complication. Yes, there is. We add a last play at the end that loses only ½ pt. instead of 1 pt. Then it does not matter who makes the last pass. The reasoning is the same as having the ½ pt. button means that it does not matter who gets the last dame.

Here comes the simplification. If the player who took the button also gets the last pass, the result for that person is -½ - ½ = -1, i.e., the same as handing over 1 prisoner. So let that person hand over a prisoner when she takes the button, and if she also makes the last pass, let that pass be for free. If the person who took the button is different from the one who gets the last pass, the result for that person is -½ + ½ = 0, the same as if she hands over a prisoner when she takes the button, and her opponent hands over a pass stone on the last pass. Voila!

Edit: OC, the territory rules produce an integer result, so we have to us komi worth ½ pt. less to make the two results the same.

[Bill Spight]

By the way, in my sgf, I can see that in all cases that I have considered, button go is equivalent to territory scoring, but with one point of territory inside the ko, if it had been left open !

That's because the button was taken with the ko ban in effect. The result would be different for the Go Seigen-Iwamoto game, because Go Seigen filled the last dame with the ko ban in effect. In that case you don't count the open ko point as territory.

[moha]

I think the biggest obstacle in wider acceptance of button go is simply that its benefits are not enough for the complications. Even pass stones - a simpler change that solves important problems - only gained narrow support (compared to Japanese/Chinese/Korean rules).

One may think a tiny extra rule is a small change, and players can be expected to learn and accept it. This is not true. Not (for example) for the majority of players who only have a rough idea of rules. And particularly not for Japanese/Korean, since territory scoring actually allows them to play the main game up to the first stop without any extra rule (besides the basics one learns as a beginner). This advantage is SO HUGE that it seems unreasonable to expect them to give this up.

For Chinese/area rules (which need some rule tricks anyway, even in the main game) it may be a bit easier, especially if the change can be formulated as a tiebreaker instead. So komi=7, ties are possible, but IF a tournament prefers to avoid them, there can be an optional extra rule with similar effect (like fewer stones played wins ties - iirc something like this was discussed in an older thread).

[Bill Spight]

What bothers me is that it is neither an area rule, nor a territory rule.

IMHO, that is the main point. Currently we have two different forms of weiqi that are very similar to each other. For international competition with players who are used to one or the other, it would be good to have a hybrid form that combines both. Button go does that.

Its true meaning is that it is an "area plus button" rule.

As a rule, correct play by button go is also correct by straight area rules, but not vice versa. IMHO, that is an attractive feature.

Practically, I am completely lost in front of a question like "should I take the ko or the button" ? The ko is said to be worth 1/3 of a point, and the button 1/2. So I should rather take the button. It is worth more.

The ⅓ pt. value is by territory scoring. By territory scoring the button is worth -½ pt.

But wait, the core rule is area, so the dame are all worth 1 point, and the ko is more like 1 + 1/3, so I should rather take the ko instead of the button.

But wait, all these are approximation, I'd better read the sequences to be sure.

Taking the button is not an approximation. As moha has pointed out, there are times when, if you have enough ko threats, not just to win the ko, but to delay winning the ko, you can profitably take the button instead of winning the ko. Similar positions arise earlier in the game in regular ko situations.

But, OMG, should I count territory + 6.5 komi + pass stones, or area + button ?

Don't worry. Just count area plus the button, as you are used to doing.

For me, area is something that can be seen on the board. Territory can't, because territory actually means territory plus prisoners plus dead stones.

Right.

[moha]

Currently we have two different forms of weiqi that are very similar to each other. For international competition with players who are used to one or the other, it would be good to have a hybrid form that combines both.

Potential result: players learn three different forms.

[Bill Spight]

I think the biggest obstacle in wider acceptance of button go is simply that its benefits are not enough for the complications. Even pass stones - a simpler change that solves important problems - only gained narrow support (compared to Japanese/Chinese/Korean rules).

Button go may be implemented to simpilify AGA territory rules by eliminating the third pass by White. It would also make the score in nearly all cases the same as most Westerners are used to, since they play by territory rules online or in their clubs. I think they would welcome the change. Having the "first pass" lift the superko ban and not count towards ending play might meet opposition, so don't call it a pass.

One may think a tiny extra rule is a small change, and players can be expected to learn and accept it. This is not true. Not (for example) for the majority of players who only have a rough idea of rules. And particularly not for Japanese/Korean, since territory scoring actually allows them to play the main game up to the first stop without any extra rule (besides the basics one learns as a beginner). This advantage is SO HUGE that it seems unreasonable to expect them to give this up.

That is one reason I recommend Button Go for international competition, and also for the AGA, which already uses pass stones.

For Chinese/area rules (which need some rule tricks anyway, even in the main game) it may be a bit easier, especially if the change can be formulated as a tiebreaker instead. So komi=7, ties are possible, but IF a tournament prefers to avoid them, there can be an optional extra rule with similar effect (like fewer stones played wins ties - iirc something like this was discussed in an older thread).

The 2008 World Mind Sports Games in Beijing implemented Button Go without calling it that. They used area counting, but implemented the button in this way.

There are two types of compensations. The first type depends on who passes first in the game. If White passes first, Black's score is reduced by 1. If Black passes first, no such compensation is given.
The second type of compensation aims to balance the advantage enjoyed by the player who makes the first play. To ensure a fair game, the Black player is asked to deduct an amount from his total points, traditionally known as the komi (tie-xian in Chinese). The amount of komi in this tournament is set to be 6.5 points.

[Matti]

In some cases the area and territory scoring are fundamentally different. See the first diagram at http://www.harryfearnley.com/go/bestiar ... ivola.html. With territory scoring the position is seki, but with area scoring once the dame have been filled, white can start filling a big eye with no extra cost, and force balck to select which white group to capture.this leaves the other white group alive with two eyes and the adjanced black group dead.