The instant that I saw the subject line on your post guess what tune popped into my head.

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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 ko rule is not much more specific. It simply forbids repeating a previous board position. What else does it prohibit?

Go Players Almanac Page 193 - Chinese Rules of Go Section 20 Reappearance of the same board position. Subpart 1. In a ko fight, if a player recaptures on the next move, the move is declared invalid...

Go Players Almanac Page194 - New Zealand Rules - A move consists of (1)making a play so that the resulting board position does not repeat the whole board position... NOTE - These rules do not even mention the word "ko".

Go Players Almanac Page 200 - AGA Rules (6)Repeated Board Position (Ko) It is illegal to play in such a way as to recreate a previous board position from the game.

I could continue, and I do not dispute that you have never seen the ko rule expressed this way - but in these sort of rules discussions, reading the rules can be helpful, and as you can see, this is a very common way of describing ko, and is the essence of the rationale for the rule.

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My days of not taking you seriously are certainly coming to a middle

Chinese rules have superko. (I remember reading something about Chinese Go having true superko in the rules, but not in actual practice, is that true?)

NZ rules have superko.

AGA rules also have superko.

Obviously all rulesets which have superko will forbid repeating a previous position and don't need a special case for ordinary kos.

But not all rulesets have superko, while all rulesets forbid kos, either by having superko or by an explicit exception. This exception is what I meant by "the ko rule", as contrasted with superko (of which I'm obviously aware - I mentioned it in my previous post). The ko rule does not talk about repeating a previous position, it talks about recapturing a ko on the next move. Japanese rules are an example.

The ko rule is absolutely essential to Go. All rule sets need to make sure that the situation is covered.
Disallowing a previous position is not essential to Go. Some rulesets may allow repetition, some may forbid it.

But why is it essential? Because without it, the board position can repeat (forever)

That's its purpose, to prevent repeating board positions (locally at least)

The saying "the board position may not be repeated" is just much more convenient than the rather involved description of a basic ko, that's why it is often colloquially used.

I think that this talk about axioms and rules is really interesting. Perhaps axioms and rules should be treated separately; axioms are not rules, but the rules ensure that the axioms are fulfilled.

So, what are the axioms?

My ideas:

• There can be no stones without liberty on the board.
• The game is of finite length.
• The game has a score when it ends.

Well, dammit, now the japanese rules are out again.

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A good system naturally covers all corner cases without further effort.

I think that your set of axioms is at least incomplete.

"The game is of finite length." is superfluous in my eyes. And it is self-evident. Limited is the lifespan of mankind, so will be that of every game.

"The game has a score when it ends." seems too much restricted and specific to me. "Score" is more restricted than "result", because it assumes that there is something countable.
What instead will be necessary is something like the following:
After the game has been terminated (by the players), it's outcome can be determined in a well-defined manner.

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The really most difficult Go problem ever: https://igohatsuyoron120.de/index.htm
Igo Hatsuyōron #120 (really solved by KataGo)

That would make for rather a boring game, lets turn that into:

• There can be no stones without liberty on the board after a player's move

Well, as I said in my first post, I knew I would regret getting involved in this. Clearly I am making no headway here. Thanks for those who are trying to help me. This is not my area, it is nice to know others think I am right - does anyone think I am wrong?

The ko rule is absolutely essential to Go - because stalemate must be avoided by disallowing a previous position. It really is that simple - that is ALL the ko rule is. You claimed earlier that the ko rule required more than that - I asked you what, but you have not specified anything.

Avoiding a previous position IS essential to determining a winner in a game of go. That is why Superko rules AND ko rules forbid it. Under Japanese rules, yes, the complexity of dealing with tripleko as a repeated board position is avoided, but so is the game result.

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My days of not taking you seriously are certainly coming to a middle

I don't know about boring, but if you forbid both suicide and capture, you get Gone, a kind of misere go where the first player to capture loses. It is a surprisingly difficult game.

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

Visualize whirled peas.

Everything with love. Stay safe.

The ko rule talks about recapturing on the next move in a ko fight. See Japanese rules for an example, but even Chinese rules put it this way. This is much more specific than disallowing repetition outright.

Exactly! Of course you need superko for a game to have a result. But as Japanese rules show, it's not essential to be able to ensure that the game always ends with a result. They have had their rules for thousands of years and are just fine with the possibility of an occasional void game. On the other hand, every ruleset must do something about regular ko, or the game would become unplayable.

This is what I had in mind when writing that the outcome must be determined well-defined.
What it is even with Japanese rules.

Think about

Click Here To Show Diagram Code

[go]$$ First move of the game.
$$ --------------
$$ | . . . . . . . |
$$ | . . . . . . . |
$$ | . . . . B . . |
$$ | . . . . . . . |
$$ | . . . . . . . |
$$ | . . . . . . . |
$$ | . . . . . . . |
$$ --------------[/go]

Click Here To Show Diagram Code

[go]$$ Last move by white.
$$ --------------
$$ | O O O O O O O |
$$ | O O O O O O O |
$$ | O O O O X O O |
$$ | O O O O W O O |
$$ | O O O O O O O |
$$ | O O O O O O O |
$$ | O O O O O O O |
$$ --------------[/go]

Should it be possible for Black to capture all of White's stones ?

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The really most difficult Go problem ever: https://igohatsuyoron120.de/index.htm
Igo Hatsuyōron #120 (really solved by KataGo)

When i learned the game i was thinking what we here is called suicide is is fact surrender.

and therefore just the same as resign.

Stones don't become dead by capturing, they become dead by not defending them.

Stones that are taken off the board are captured, and letting your self capture (by renmoving all your liberties is something like surrender.

And surrendering is similar to resigning.

Off coourse my japanese is hardly enough to conform all this.


A more rule theoreticly stanpoint.

Would it matter?

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Promotor and Librarian of Sensei's Library

Allowing suicide is completely logical. Just because it may seem counter-intuitive does not mean it is not a good move in some cases. A game could even end with an incorrect result because of the no-suicide rule. Or should it be illegal to sacrifice stones or put yourself into atari?

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"Those who calculate greatly will win; those who calculate only a little will lose, but what of those who don't make any calculations at all!? This is why everything must be calculated, in order to foresee victory and defeat."-The Art of War

"Sacrifice" is a tactical measure that requires efforts by the opponent to kill.

To kill yourself by your own (= "suicide") exempts the opponent of these efforts. So it's a different kettle of fish.

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The really most difficult Go problem ever: https://igohatsuyoron120.de/index.htm
Igo Hatsuyōron #120 (really solved by KataGo)

I realise that this has been said before, but these are completely different things to compare. Suicide involves reducing the liberties of your own stones to 0 without capturing one of the opponent's stones. Sacrificing stones or putting yourself into atari is covered by the normal rules, but the interruption to the flow of the game caused by capturing your own stones necessitates a further rule (one way or the other), and it isn't clear to me why any option should be more obvious than the other. Certainly, people don't all find the same option intuitive.

Whilst allowing suicide is completely logical, so is forbidding it.

Folks, seriously, what we really need is a rule that prevents me from playing self-atari. Isn't that called suicide?

no Suicide and self-atari are completely different situations

Suicide is having NO liberties (and your stones need to be removed / the move is illegal)

Self atari is having only ONE liberty left, your stones stay on the board but your opponent CAN capture your stones ON HIS NEXT MOVE. (but this is nt an obligation

Here i need even make an exemption for ko situations where the opponent is not allowed to recapture the stone but the stone just played is in atari and can be called a self atari.

If you want to forbid self atari you are talking about something similar to atari go. http://senseis.xmp.net/?AtariGo athough there it is not forbidden but your opponent will win after capturing you (what is not legaly the same but in practice it makes no difference)

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Promotor and Librarian of Sensei's Library

willemien, please re-tune your joke detector. :p

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a1h1 [1d]: You just need to curse the gods and defend.
Good Go = Shape.
Associação Portuguesa de Go

All, the Japanese no result rule does not always define an outcome:
http://home.snafu.de/jasiek/j1989c.html

Harleqin, a carefully written ruleset of rules of play can consist of one of the following:
- axioms and definitions (e.g. Japanese 2003 Rules)
- definitions
- rules
- axioms and rules
- axioms and definitions and rules
- definitions and rules
Note that rules are just carelessly circumvented definitions. Rules written down carefully can be reduced to definitions, which in turn rely on axioms.

Cassandra, where can we read the Japanese 1996 Rules? Is it available in English? How does not differ from the 1989 Rules? Is the 1996 version the latest?

What kind of ruleset do you have in mind ?

The latest Nihon Kiin rules date from 1989.

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The really most difficult Go problem ever: https://igohatsuyoron120.de/index.htm
Igo Hatsuyōron #120 (really solved by KataGo)