[admin]
In another thread, the issue of group tax arose. I'm moving that to its own thread, partly to avoid derailing the prior thread, and partly because I - as a player - think that the subject deserves its own thread.
I edited out some of quantumf's text that applied to the prior thread. -JB
[/admin]

I was ...also struck by the group tax - when did this end, and why?

More curiously, I have always wondered why it started in the first place.

_________________
Still officially AGA 5d but I play so irregularly these days that I am probably only 3d or 4d over the board (but hopefully still 5d in terms of knowledge, theory and the ability to contribute).

The group tax was a feature of both the oldest known area scoring rules and territory scoring rules. It may well have been a feature of even older forms of go.

Curiously, if you make go rules with no passes and prisoner return, you naturally get territory scoring with a group tax. The Capture Game with no passes also yields territory scoring with a group tax.

Perhaps the oldest form of go was a no pass game. Interestingly, one of the questions that arose from the Segoe-Takahashi 10,000 year ko rules dispute was whether making a play was a right or an obligation. The pass as we know it was not part of the game. Games ended by agreement, which is the normal way of ending no pass games that have an obvious way of scoring.

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

Visualize whirled peas.

Everything with love. Stay safe.

I think no matter which scoring system you use a group tax should be implemented.

The group tax seems so natural.

Can u pls explain.

If you place stones in empty area in your territory and then count the number of stones you placed (stone counting method) you get to see something very interesting.

Let's say that black has 3 groups on the board and after filling everything up you count the number of stones on the board and black has let's say 50 stones (50 points).

Now imagine if all the black groups were connected in one group. This means that you can still place 4 stones on the board (where the two eyes of the two previous groups were) and by doing that you get 4 points more.

This is why in group tax you have to pay 1 zi or 2 points for every group you have.

Are you using territory scoring or area scoring here ?

Sure. Consider this whole board position, with no captured stones.

Click Here To Show Diagram Code

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

The game is no pass go with prisoner return. Prisoner return means that on your turn you can return a prisoner instead of playing a stone on the board.

At this point the players could agree to stop play and score the game. Black has three one point eyes and can fill one of them safely. So Black has one move in her territory, which means one point. White has two safe moves in his territory and thus has two points. White has one more point than Black and wins by one point (move). The group tax simply means that neither player can afford to fill his next to last eye. The fact that White is one point ahead means that he wins even if he plays first.

For instance:

Click Here To Show Diagram Code

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

resigns.

Note that White just barely wins. If it were White's turn he would resign.

Next, an example with prisoner return:

Click Here To Show Diagram Code

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

In straight no pass go, without prisoner return, Black has two moves (points) while White has one point. Black wins even if she plays first.

Click Here To Show Diagram Code

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

resigns.

But in no pass go with prisoner return, the scores are the same as by territory scoring with a group tax. Each player has two points, four points before the group tax. The net score is 0.

In no pass go a zero means that the player with the move loses.

If Black plays first:

Click Here To Show Diagram Code

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

returns the prisoner.

resigns.

If White plays first:

Click Here To Show Diagram Code

[go]$$W
$$ -----------
$$ | . X 4 2 . |
$$ | X X X X X |
$$ | O O O O O |
$$ | . O O B 1 |
$$ -----------[/go]

returns the prisoner.

resigns.

¿Es claro?

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

Visualize whirled peas.

Everything with love. Stay safe.

Complicated, but clear. But in Spanish it is ¿está claro? (Is it clear?) Es claro? Actually translates the same on first sight, as Is it clear? But actually, no: Is it light (shade)?

Spanish and ser/estar. Confusing people since forever

_________________
Geek of all trades, master of none: the motto for my blog mostlymaths.net

? What are the respective ages of the question mark and the inverted question mark ¿

I was also curious heh. It is formally used, but in common day use it is of course skipped.

_________________
Geek of all trades, master of none: the motto for my blog mostlymaths.net

I thank you. My grammar thanks you.

Which reminds me of an old, bad joke.

Gringo, wishing to break the ice on a hot day: Está usted caliente?

Señorita, wagging finger: No, señor! No! No! No!

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

Visualize whirled peas.

Everything with love. Stay safe.

Btw, a reason for the double question marks probably stems from the fact that some questions in Spanish are just the same as declarative sentences. So, an initial mark clarifies the type of sentence.

_________________
Geek of all trades, master of none: the motto for my blog mostlymaths.net

Sometimes with friends, I use the period instead of the question mark, "How are you." Is this bad ?

Thanks for the explanation for those of little brain, but I still don't get it. First of all, "stone counting method" means that whoever has the most stones on the board at the end wins, right? If so, having three groups instead of one lets you place fewer stones. Why then should you be further penalized (taxed) for having played less optimally? It seems to me that it should be just the opposite, that one should receive a tax break of two stones for each extra group, that way such a game as this (from the stone scoring page of SL) would be a tie as it is under territory or area scoring (note that w has captured three stones and black one).

Click Here To Show Diagram Code

[go]$$B example game 2, moves (25 _ 34)
$$ ------------
$$ | . X X 3 O . |
$$ | X . X O 4 6 |
$$ | X X 2 O O O |
$$ | O O O 1 X X |
$$ | 8 O X X . X |
$$ | . O O O X . |
$$ ------------[/go]

What am I misunderstanding?

_________________
Patience, grasshopper.

Again the guy with little brain, and for me the waters are murkier than ever. Doesn't "group tax" mean that you pay a penalty for having more groups? In this strange variation of go you show in which you have to fill in your own eyes, neither side has more than one group.

In the following paragraph, I got lost 5 times. The sentence in blue is the only one I understood.



1. "At this point the players could agree to stop play and score the game." So they don't have to keep playing. What are the rules of this game?

2. "So Black has one move in her territory, which means one point." After playing that one stone, black has either two points of territory, or has played 8 stones. How do we arrive at one point? How is this game scored?

3. "White has two safe moves in his territory and thus has two points. White has one more point than Black and wins by one point (move)." Are these the two points of territory or the two played stones?

4. "The group tax simply means that neither player can afford to fill his next to last eye." This is what group tax means? It seems rather something of a truism that one can't afford to fill in one's next to last eye. What does this have to do with tax?

5. "The fact that White is one point ahead means that he wins even if he plays first." Good for him. So what?

All of the following diagrams made sense to me, but I have no idea what they have to do with group tax.

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Patience, grasshopper.

Strategy, strategic concepts (such as efficiency) and strategic penalties for bad strategic choices become meaningful AFTER the rules (with some scoring system) have been chosen.

However, one can design rules so that they fit certain desired strategic behaviour. For this purpose, strategic behaviour must be given in a broader context of a generic space of rulesets. One first chooses a desired general strategic behaviour, then designs a fitting ruleset, then develops strategies as applications of that ruleset and, if everything was designed and defined well, all such strategies fit the presupposed general strategic behaviour.

Group tax does not per se mean efficient or inefficient strategic behaviour. It all depends on one's chosen context. Under different contexts, one perceives either efficiency or inefficiency. If considering ONLY the number of a player's groups under, e.g., stone scoring, building many groups is inefficient. If considering a broader strategic context, there can be strategies in which building many groups is efficient when the implied group tax is an implied sacrifice to improve on the score in other respects.

This is another case of a modern term not properly reflecting the ancient one, which was "two overflowing".

The currently definitive text on rules history is 围棋规则演变史 (History of the evolution of weiqi rules) by Chen Zuyuan (ISBN 978-7-80740-147-6).

It's a rather long book, and the relevant portion is on page 80, referring to the Dunhuang Go Classic. I did summarise the main arguments in New In Go. For those that haven't got that, one of the main points is that Japanese scoring and Tang counting are not quite the same thing. It can be shown, by textual exegesis, that Tang counting requires both sides to play an equal number of moves (which is why I presume Bill is stressing prisoner return). By a more complicated route it can be demonstrated that "two overflowing" refers to what we, not they, called group tax, but it was not clear cut to ancient Chinese what it meant, and had to be spelt out by Liu Zhongfu in the 12th century. Bill's claim (if I understood him aright) that group tax is a natural way for go to evolve may, therefore, be on slightly shaky ground. There is evidence in the Dunhuang Classic to suggest it was known then, i.e. centuries before Liu, but there is also an indication that the "two overflowing" term may be an allusion to the Analects of Confucius, in which case it may be an artificial rather than a natural construct.

The naturalness of any part of the evolution is also open to interpretation in light of whatever Korean and Tibetan rules tell us, not to mention the possibility of variant forms co-existing (see e.g. the Heaven and Earth variant). Again, I refer you to Chen for details.

Is it!

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

Visualize whirled peas.

Everything with love. Stay safe.

These days people say "How are you" as a formality and not expecting anything except a form answer. If you actually told them they would wonder what was wrong with you. So it really isn't a question.

_________________
Still officially AGA 5d but I play so irregularly these days that I am probably only 3d or 4d over the board (but hopefully still 5d in terms of knowledge, theory and the ability to contribute).