Today I played around a little bit to see how group tax or not affected KataGo's suggestions.

For those unfamiliar - group tax means that the two eyes that a group needs to live are not counted as points, so effectively it's -2 points for every independent group, except for seki groups, where they just lose only the points for whatever eyes they do have. Or, a cleaner way to think of it that makes it clear that this isn't just some arbitrary rule - if you do this on top of normal area scoring, this basically gives you stone scoring - your score is simply how many stones you can actually fill on to the board (and counting and subtracting two for each group is simply a shortcut to doing this instead of actually placing all the stones). Ignoring the actual rules history, which is a bit more interesting and I don't claim to be an expert on, and just "morally" speaking: you can think of this as sort of where Japanese "no points in seki" comes from - in addition to the territory vs area difference, the specific bit about "there is no territory in seki" can be thought of as a holdover from group tax rules, where the 2 points tax for living groups was discarded but the seki bit remained.

Anyways, KataGo plays about 20% of its self-play games using such rules, so in theory it should have extensive and superhuman-level practice with the strategic implications. Players should be more eager to connect on a large scale and make fewer groups, and to try to split the opponent's groups apart. And indeed it does seem to make a noticeable strategic difference in many opening positions. If you're one of these people who like center-oriented large-scale coordination play and find it disappointing that moves like 3-3 invasion are all the rage nowadays, you might like to play with group tax rules. Because with group tax, if you trust KataGo now 3-3 invasion becomes a pretty disfavored move, and also a lot of center-oriented cutting or covering moves become emphasized.

Maybe we can get OGS to implement these rules.

I'm posting some screenshots just for fun, other people should feel free to also try. If you want to compare, easiest way is if you can have two instances of Lizzie or your favorite review program open, each one set to different rules, and make moves in both at the same time, but also if you want to do it within just one instance, in a GTP console it's 'kata-set-rule tax all' to turn on group tax and 'kata-set-rule tax none' for Chinese style all-territories-count and 'kata-set-rule tax seki' to tax just territory in seki, like in Japanese rules.

The below are also with analysisWideRootNoise 0.04 to encourage evaluating more moves. All winrates and leads are from Black's perspective.

Normal - we see the usual bot preference for 3-3 invasion, but close behind are the approaching moves and developing the 3-4 corner stone.


With group tax - now 3-3 invasion is entirely off the radar, and developing 3-4 is the clear winner.

Normal - in response to white's pincer, there's a preference for dodging into the corner, leading to a pretty usual joseki, although other moves are possible.


With group tax - now dodging into the corner is barely considered and black prefers the more global splitting move that moves out into the center, for the upper left fight.

Normal - black prefers to pincer the white stone, which was also the move in the real game.


With group tax - although the pincer is still very good, now a covering move also becomes very good too, which should be more likely to result in fewer groups. Also, black is noticeably behind here, due to having the isolated group in the lower right from the earlier 3-3 invasion, wheres white does not have any fully isolated groups yet.

Verrrrrrry interesting, lightvector. Thanks.

Before the virus altered my life expectancy, and hence, my priorities, one project I had in mind was developing a bot to play no pass forms of the Capture Game. It is possible to score those games, and it turns out that they use territory scoring with a group tax. Capture-N, as N increases, approaches the ancient Japanese form of go, with territory scoring and a group tax.

My guess is that a strong capture game bot would value the center, strategically, because of the group tax, and would also be good at semeai, given the fact that winning a semeai could win the game by sudden death. One large enough capture would be enough. OTOH, it might be very good at avoiding semeai. Quien sabe?

_________________
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At some point, doesn't thinking have to go on?
— Winona Adkins

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Hi lightvector,

All of your examples are Black to play, and with a group tax, Black prefers to have more large scale development.

Would it be true that White prefers small groups with a group tax, since komi is more likely to matter?

No, I'm quite sure that white prefers the same things black prefers - white should avoid early 3-3 invasions, and should prefer to connect and cut stones on a large scale, such as slightly favoring central groups that enable global connectivity and slightly disfavoring invasions that live isolatedly, compared to normal go. Playing white isn't going to suddenly reverse the preference. Having numerous small groups as white instead of fewer groups still means you get taxed more... which is bad, not good!

"Komi is more likely to matter" seems to me the wrong way to think about it. It's just normal go, but you're going to sometimes get +2 or +4 points compared to normal, and sometimes -2 or -4, based on the different of number of groups relative to the opponent. And of course, in Japanese rules which have a 1-point granularity, this will smooth out in between as well due to choices and trades (e.g. a line that gives you an extra group being 2 points worse perhaps means that instead you opt for a line that is 1 point worse compared to normal Go, so then group tax net would change the result by 1 point, which is not a multiple of 2). Komi shouldn't be really either more influential or less influential than usual, because to a first approximation there shouldn't be much special interaction between the value of komi and the number of groups you end up with, except for the fact that they add up.

KataGo seems to judge having group tax as about +1% winrate for black relative to normal rules in both Japanese 6.5 komi and Chinese 7.5 komi variants, meaning that black starts out a little less behind than before. This is consistent with an intuition that black should find it slightly easier to have fewer groups than white, due to being a move ahead. And since early opening positions are seen millions of times in self-play, before the game develops into its own unique state, such differences, although well below the normal error margin that one would consider to be trustworthy for later in the game, probably do reflect real differences in the empirical frequency of wins versus losses between these rules at the bot's current level of play in training games.

But 1% also seems very slight (slighter than I might have expected), and being ever so slightly harder on white shouldn't cause white's preferences to reverse. White of course wants the same things, even if slightly harder.

If you have KataGo working, you can try it all yourself.

This is just brilliant, lightvector!

Truly original work.

Myself I'm a firm believer that the game originated as stone counting and area counting was just practical. Group tax was probably discarded as a matter of elegance and because it didn't matter all that much in times when even komi was not a practice. Speculative I admit. Although that's now what the game has become, I can't help but feeling that group tax would stay truer to the original game. As you have proven, the cosmic style would highly benefit from it, which is another romantic reason to favor it.

Thanks a lot!

I remember watching/reading a commentary (EDIT: https://lifein19x19.com/viewtopic.php?p=213010#p213010) on an ancient Chinese game, where the point was made white would play this checking move from outside rather than 3-3 like we would now because of the group tax:

Click Here To Show Diagram Code

[go]$$W
$$ . . . . . . . . . . . . |
$$ . . . . . . . . . . . . |
$$ . . . . . . . . . 1 . . |
$$ . . . . . . . . . . . . |
$$ . . , . . . . . X . . . |
$$ . . . 3 . 2 . . . . . . |
$$ . . . . . . . . . . . . |
$$ . . . . . . . . . . . . |
$$ ------------------------+[/go]

Thanks for the response lightvector, Based on what you said, I think I didn't state my question as clearly as I could have.

(bolding is mine)


I was not trying to say that it should be white's goal to create as many small groups as possible, irrespective of what black is doing. What I was saying is that, in games that occur where *both sides* end up with numerous small groups, that the margin of victory tends to be small, and komi is therefore more likely to matter, favoring White


But I certainly defer to KataGo. Thanks again.

Granularity is the wrong word because it is 1 for territory, area and stone scoring.

Instead, you mean the smallest score difference under the assumptions of a 'constant seki parity' and possibly 'no asymmetrical seki'.

According to Ing, stone scoring persisted in parts of China into the 20th century. When the group tax was dropped from Japanese territory scoring, I don't know.



I like the idea, too. Bring back the group tax!

_________________
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins

Visualize whirled peas.

Everything with love. Stay safe.

I'm not so sure, on 9x9 often you have black with one big group and white with two small groups. I'm not sure 7 komi is still accurate with group tax. It might be, but I haven't researched it.

Wasn't group tax abandoned after the logical leap was made to territory? It makes little sense after that. (AFAIK area was only a very late invention.)


This may be true for pros, but this could also break the game at amateur levels. It's already too easy to win mindlessly dropping random high stones, weaker players cannot play well against influence. The balance is delicate.

John Fairbairn can correct me, but the oldest known description of weiqi suggests stone counting, while the oldest existing scored game records appear to have used territory scoring with a group tax. Berlekamp showed that no pass go with prisoner return may be scored with territory scoring with a group tax. (I have shown that other forms of no pass go may be scored with territory scoring with a group tax, depending on the definition of territory. ) It is quite possible that some precursor of ancient go as we know it was a form of no pass go. In any event, it is not necessary to assume that territory scoring was derived from area scoring, or vice versa.

_________________
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins

Visualize whirled peas.

Everything with love. Stay safe.

I meant: stone scoring -> territory scoring with tax -> drop tax.

I'm not sure I can. Rules bore me. What I can say is that, for those who have GoGoD's New in Go (which, I think, comes with the GoGoD database) GoGoD published, at Chen Zuyuan's request, our English version of a paper of his on the history of go rules. Most of the answers are in there.

Chen is the world's premier rules researcher, not least because he can read all the old texts. He has continued his research, and one later item is a major book on cyclic kos. A further huge addition to the go canon is a joint work last year with pro Li Zhe which shows that Chinese go theory was far more advanced than previously thought even in China. And since it predated by a very long time anything written down in Japan, it was presumably well in advance of Japanese theory. Whoever did the PR job for Japanese go was the kind of guy that it looks like President Trump might now need.

What I can add, peripherally, is that there is no actual evidence that group tax was ever used in Japan. Or starting stones, if we accept the pretty overwhelming evidence that the Nichiren game was a forgery. Hayashi Genbi may still be blushing in Heaven.

The Japanese term for group tax is kirichin (cutting tax) but this was a term made up by Japanese go researchers. They also were the ones who decided to call the rules they originally inherited from Tang China "Japanese rules" (and the two stages of more recent Chinese rules were dubbed Primary and Secondary Chinese rules, the latter being the version with group tax removed). They freely acknowledge the misnomer, but it did at least reflect modern practice. However, when they talk about Tang rules, they specifically call those "Japanese rules with group tax" (切り賃つき日本)ルール), but given they accept the misnomer that really means "very old Chinese rules with group tax".

The only element of Japanese play that hints at group tax is the rule about not counting points surrounded in a seki, but that can be twisted to support any inside in any argument. The usual cop-out is to refer to Primitive Rules, which nobody actually knows, and the evidence from Tibetan and Mongolian go warns us that it would be rash to make assumptions based only on what we know as of now. We will probably have to await deciphering of the still unread cache of Tibetan documents found not too long ago in Gansu Province to find more clues from that far back.

Apart from some tantalising allusions to go in the Tale of Genji and The Pillow Book (which I covered extensively in New in Go), and of course the Shosoin boards, the history of go in Japan is a blank page for the equivalent era there. The first work to discuss theory, in a very minor way, was the Igo Shiki of 1199. Then, apart from game records and some poems, nothing till about the time of Mozart and Beethoven, and nothing really substantive till Honinbo Shuho at the end of the 19th century. Rules research is a very recent thing in both Japan and China. Japan probably has the lead there, from about the 1920s, but that was stimulated by what they discovered when they invaded China.

Chen makes the reasonable assumption that the group tax was originally a feature of stone scoring, and was carried over to territory scoring when that change occurred, at some point before the time of existing scored game records. If you start with territory scoring, it is far from obvious how you get a group tax, nor is it obvious why a dead stone counts as one point of "territory". But if you start, as Berlekamp did in the '80s, with no pass go, the group tax is an obvious feature of territory scoring, and I later showed that, from that standpoint, dead stones are part of the definition of territory. To derive something like modern Japanese and Korean territory scoring, Berlekamp had to go to some trouble to eliminate the group tax.


Before Davies came up with the terms, territory scoring and area scoring, territory scoring was informally called Japanese scoring and area scoring was informally called Chinese scoring. Not exactly correctly in either case. We have ancient Chinese game records that appear to use territory scoring with a group tax, but no such Japanese game records with a group tax. If the group tax was dropped from weiqi before Japan inherited it from China, then it was not used in Japan, but if the group tax was still part of the rules in China, then it is very likely that it was inherited by the Japanese. But there is no direct evidence either way.



With the understanding that very old Chinese rules counted territory, dead stones, and prisoners.



Well, if they adopted the very old Chinese rules as we know them, the group tax would have applied to certain points of territory in seki. It is easier to tell a story of how the rule about not counting territory in seki arose from the group tax than to tell a story of how it arose de novo. No copout is necessary.

But yes, we do not know where or when territory scoring dropped the group tax, or how the special rule for seki arose.

_________________
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins

Visualize whirled peas.

Everything with love. Stay safe.

He is the world's premier researcher in the history of old go rules. I am the world's premier researcher in modern go rules theory.

If that's true, you can no doubt share insightful views on, say:

1. 世界の囲碁ルール (Go rules of the world) by O Meien， 2019，especially Chapter 7 on his suggestions for 純碁 or pure go。

2. 围棋规则演变史 (History of the evolution of go rules) by Chen Zuyuan, 2007, especially on the modern developments in the "Path to unification" (Chapter 6).

3. 囲碁ルールの研究 (Go rules research) by Sekiguchi Harutoshi, 2007. Comments on the perfectibility of rules (page 150) will do.

Finding logical flaws in rule sets is just pulling legs off spiders. Some researchers are concerned with symbiosis.