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 Post subject: strange seki
Post #1 Posted: Tue Oct 27, 2020 6:30 pm 
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i can't seem to find the game in my game records, but i once had a position that was seki in double ko.
neither player could capture the other, unless they made a stupid mistake and filled.
the primary problem was, how are points counted for the group under aga rules?
my personal rule is: if a player surrounds an intersection, and can't be taken away by the opponent, then its a point.
but this rule breaks down with this position. either player can indefinitely capture and recapture.
its just that doing so doesn't improve or worsen the score.
hypothetically if the game isn't timed, it could go on forever.

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Post #2 Posted: Tue Oct 27, 2020 7:56 pm 
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phillip1882 wrote:
i can't seem to find the game in my game records, but i once had a position that was seki in double ko.
neither player could capture the other, unless they made a stupid mistake and filled.


See this page on Sensei's Library. https://senseis.xmp.net/?DoubleKoSeki

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the primary problem was, how are points counted for the group under aga rules?
my personal rule is: if a player surrounds an intersection, and can't be taken away by the opponent, then its a point.


That's my understanding of the AGA rules.

Edit: To be clear, if the players disagree about whether a point is surrounded by dead stones, they may resume play. But any superko ban remains in effect.

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but this rule breaks down with this position. either player can indefinitely capture and recapture.


The AGA superko rule prevents indefinite repetition of double ko seki. See https://senseis.xmp.net/?SituationalSuperko

Edit: To be clear, the ko eyes in the double ko seki cannot be taken by taken away by the opponent by indefinite capture and recapture because the opponent is prevented from doing so by the superko rule at the end of the game. OC, the players may end the game without trying to play on forever.

:)

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Last edited by Bill Spight on Wed Oct 28, 2020 12:45 am, edited 1 time in total.
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 Post subject: Re: strange seki
Post #3 Posted: Tue Oct 27, 2020 10:55 pm 
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Superko applies so endless repetition does not occur.

It is immaterial how things are counted - what matters is what scores.

Scoring applies at the game end after the final passes.

According to the rules, "Those empty points on the board which are entirely surrounded by live stones of a single color are considered the territory of the player of that color.". What the rules actually mean is: "Those empty points on the board which are entirely surrounded by stones of a single color are considered the territory of the player of that color." That is because of the rule "The game is over when the players agree on the status of all groups on the board, or, failing such agreement, if both players pass twice in succession. In this case any stones remaining on the board are deemed alive.". If the players disagree and after both players pass twice in succession (and White makes the last pass), any stones remaining on the board are deemed alive. An empty intersection (sorry, for the sake of confusion with the scoring unit, called "point" in these rules) adjacent to, what one might call, a ko stone is then entirely surrounded by stones of a single color and hence scored for their player.

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 Post subject: Re: strange seki
Post #4 Posted: Wed Oct 28, 2020 1:54 am 
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The answers to this seem slightly misleading to me in that it implies AGA rules are important in the scheme of things. Are they? Who uses superko in real life?

I'm relying on memory, but I think the 2010 game with Gu Li was the only one to implement a superko ruling in the pro world and that was under Ing rules. Apart from that, have not all (and certainly most) triple kos been treated as void games - and that despite the fact that superko technically exists in Chinese rules?

If pros decide life is too short to worry about superkos, why should AGA rules try to buck the trend? I'm sure in practice US amateurs take the same pragmatic view as the pros anyway, which is what the poster seems to have done with his "personal" view. Long live persons!

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Post #5 Posted: Wed Oct 28, 2020 3:08 am 
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Chinese Rules are a separate issue because not all of its authors might have been aware of the existence of superko but chosen a careless wording, which people aware of superko interpret as superko but the Chinese Rules authors have only meant to apply to sending-2-returning-1 while otherwise the referee ko rules take precedence. Last, I asked a Chinese professional and international referee who was not aware of the existence of the superko rules concept.

Apart from sending-2-returning-1, whose practical behaviour is agreed upon, the long cycle ko rules are rarely relevant at all: depending on the players, relevant shapes occur in 1:20,000 1:5,000 or for some rare players 1:1,000 games. Even among those shapes occurring at all, some have the same strategic behaviour. A genuine triple ko (composed of one, two or three shapes) may be the most frequent kind for which strategic behaviour differs.

Superko rules apply as such in New Zealand Rules (few players, few games), Simplified Ing Rules (in some of the European Go Congress main tournaments etc. but such has become infrequent after Ing sponsoring of the EGF has been abandoned), AGA Rules (in some AGA tournaments), French Rules (in some French tournaments) and BGA Rules (in some BGA tournaments), some other tournaments. This means that we have relatively few games for which there could be reports with different strategic behaviour of superko at all.

That there have been a few AGA tournament reports with superko not having been applied correctly (scandal attracting motivation of being reported) does not mean that otherwise in AGA or non-AGA tournaments superko would not have been applied correctly. Correct application does not attract reports easily. So witnesses are requires that then report and correctly so.

While I did witness a Ing 1991 ko dispute (and was readily called by the referee as an expert), I do not recall to have witnessed a game under superko with a position of strategically different superko behaviour. In my own (60,000 or 70,000?) games, I had two double ko sekis (but they alone would not create a different strategic behaviour) and one triple ko (double ko death and a basic teire ko elsewhere; interesting because I knew correct strategy of omitting reinforcement but could not play strategically correctly allowing my opponent many virtual ko threats due to sudden death thinking time, only a few remaining seconds and had to compromise in order to win the game) but in particular the latter was not played under superko.

Since Asian professionals in Asia play hardly any superko rule games, this is much more a matter of their practice than preference. I guess most Japanese pros would favour their applied rules tradition. Chinese professionals, as far as I have asked them, are roughly split 50:50. Korean professionals I expect in between. I forgot to ask the one Taiwanese professional I met.

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 Post subject: Re: strange seki
Post #6 Posted: Wed Oct 28, 2020 4:17 pm 
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phillip1882 wrote:
hypothetically if the game isn't timed, it could go on forever.

In a general sense a single double ko seki is not a real perpetual cycle since - unless both players cooperate - it repeatedly triggers two successive passes (game stops).

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 Post subject: Re: strange seki
Post #7 Posted: Wed Oct 28, 2020 4:44 pm 
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John Fairbairn wrote:
If pros decide life is too short to worry about superkos, why should AGA rules try to buck the trend? I'm sure in practice US amateurs take the same pragmatic view as the pros anyway, which is what the poster seems to have done with his "personal" view. Long live persons!


AFAICT, the AGA rules are derived from Ing's 1975 rules, which included a superko rule. Ing later changed his mind and came up with idea of fighting and disturbing kos, a double ko seki being an example of a disturbing ko.

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 Post subject: Re: strange seki
Post #8 Posted: Wed Oct 28, 2020 5:45 pm 
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I think the compatibility of widespread triple ko rules in Asia is no coincidence. The three large go playing countries share the history of the game, which includes knowledge of triple kos and void games. Changing well established things is hard, especially without reasons for such change. AGA had more freedom to invent/adopt new rules.

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 Post subject: Re: strange seki
Post #9 Posted: Thu Oct 29, 2020 5:10 am 
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Thanks for the explanations about superko, Robert.

I don't know why the superko rule was first created. I guess that it is because void games, or ties, can't be dealt with within some kind of tournaments, like single elimination tournaments, for example.

But nowadays, superko is also necessary for artificial intelligence. A rule with endless repetition left to the referee to assess can't be translated algorithmically into a computer program.

RobertJasiek wrote:
According to the rules, "Those empty points on the board which are entirely surrounded by live stones of a single color are considered the territory of the player of that color.". What the rules actually mean is: "Those empty points on the board which are entirely surrounded by stones of a single color are considered the territory of the player of that color." That is because of the rule "The game is over when the players agree on the status of all groups on the board, or, failing such agreement, if both players pass twice in succession. In this case any stones remaining on the board are deemed alive.".


That's right.
The french rule is interesting because if we leave aside the teaching parts, and read only the rules statements, the final score is defined without relying on such concepts as life or death.
The meaning of the AGA rule is thus the wording of the french rule.

What's interesting is that it allows complete novices, who discover the game by themselves, to try it and score their first game by themselves.
It is not possible for a novice player to tell who's the winner if the life and death status of each group must be assessed first. I have met two people already, fond of board games, who knew the game of go, but had never played it because when they tried, they failed to understand who was the winner.

Stating that any set of connected intersections that are surrounded by stones of the same color is a territory, without telling if these stones are dead or alive, also allows neural networks to score their self-learning games without any external intervention.

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 Post subject: Re: strange seki
Post #10 Posted: Thu Oct 29, 2020 7:11 am 
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Pio2001 wrote:
But nowadays, superko is also necessary for artificial intelligence. A rule with endless repetition left to the referee to assess can't be translated algorithmically into a computer program.

Triple ko draw is not much harder than triple ko forbidden. These programming difficulties are exaggerated, as shown by Katago. Even LZ only knows a rough approximation of some TT-like rules (it doesn't see enough history to understand all cycles and superkos).

The point is, in practice approximations are possible and sufficient. The superko rule itself is also only an imperfect approximation of the real game. See also the last Go AI World Championship where special button like rules were used, which many programs likely wasn't even aware of even though it could reverse some close games.

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 Post subject: Re: strange seki
Post #11 Posted: Thu Oct 29, 2020 7:39 am 
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Quote:
But nowadays, superko is also necessary for artificial intelligence.


No it isn't. You just make void game a valid result.

Quote:
Triple ko draw is not much harder than triple ko forbidden. These programming difficulties are exaggerated, as shown by Katago.


Correct. I don't think anyone can reasonably argue even that superko is desirable, let alone necessary. If a bot is to be made capable of playing against humans (the vast majority) it has to be able to play the same rules as humans. In exactly the same way it has to be capable of accepting a jigo when the human sets the komi at 0.

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Post #12 Posted: Thu Oct 29, 2020 8:15 am 
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It is insufficient for a void game to be a valid result when AI shall make decisions. Decisions must also be decidable. This is achieved by, e.g., specifying that the result "void" equals the result "score 0" for the sake of strategic decision-making.

Superko can be seen as desirable because it is the simplest rule text and smallest number of rule cases for preventing infinite game play.

Superko is not necessary for the sake of preventing infinite game play because alternative ko rulesets exist to achieve that. For each of them, the same applies. For this specific purpose, one can choose any ko ruleset achieving it but does not need to choose any particular. In particular, one does not need to choose a ko ruleset comprising a basic ko rule, a void result ko rule and a hypothetical ko rule, as is certain tradition.

The same rules as humans? 1) Humans have different rulesets. 2) Encoding some of them is more difficult than creating an AI go software for simple go rules:)

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 Post subject: Re: strange seki
Post #13 Posted: Thu Oct 29, 2020 9:43 am 
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Quote:
It is insufficient for a void game to be a valid result when AI shall make decisions.


Robert: in most cases of colloquial English, sollen != shall. Say something like "when AI is supposed to make decisions." (Or expected to, etc - anything but shall.)

And if that's not what you mean, I have absolutely no idea what you mean.

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 Post subject: Re: strange seki
Post #14 Posted: Thu Oct 29, 2020 9:54 am 
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John Fairbairn wrote:
Quote:
It is insufficient for a void game to be a valid result when AI shall make decisions.


Robert: in most cases of colloquial English, sollen != shall. Say something like "when AI is supposed to make decisions." (Or expected to, etc - anything but shall.)

And if that's not what you mean, I have absolutely no idea what you mean.


The indicative makes is probably good enough with when. Grade school grammar calls it present tense, but it is often used without regard to time. In this case we have a condition which could occur at any time.

When I was a kid, shall was on its way out in American English as indicating future tense. Now the pluperfect has virtually disappeared.

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 Post subject: Re: strange seki
Post #15 Posted: Thu Oct 29, 2020 10:19 am 
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Shan't we remember Thatcher for her Queen's English ("We are the Prime Minister!") and me for non-colloquial speech?;) At (why, German, of course) school, we were taught shall = sollen | werden. For a few years after school, use of shall / shan't was much appreciated. Afterwards, it has become a sacrilege to dare using either. Only this Queen may use them;)

"is supposed to" is fine.

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 Post subject: Re: strange seki
Post #16 Posted: Thu Oct 29, 2020 10:36 am 
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Quote:
Now the pluperfect has virtually disappeared.


And the past historic in French is on the critically endangered list, too!

More and more, young people are rejecting the past. O tempora! O mores! Or in modern yob-speak: OMG.

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Post #17 Posted: Thu Oct 29, 2020 1:43 pm 
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jann wrote:
The superko rule itself is also only an imperfect approximation of the real game.


What's the "real game" ? Since I'm playing in France, for me, the real game uses natural situational superko. That's the official rule. :salute:

John Fairbairn wrote:
Quote:
But nowadays, superko is also necessary for artificial intelligence.


No it isn't. You just make void game a valid result.


Ok, but you need to decide a rule of some kind, that will define exactly when a game is void. Because the japanese style rules only states that it occurs when none of the players "is willing to stop the repetition", which is a subjective condition.
For example we can set a given number of repetitions a the limit. That's a "superko rule" in a broad sense.

John Fairbairn wrote:
I don't think anyone can reasonably argue even that superko is desirable, let alone necessary.


Why not ? With positional superko, a triple ko is exactly the same thing as a simple ko. You need to have enough ko threats in order not to be the one loosing the battle. Why is that bad ?

A void game has stranger consequences on the strategy : facing a choice between creating a double ko seki (A) or creating a triple ko (B), a player who is in a bad situation on the board would prefer the triple ko, allowing him to restart the game.
Why not letting him face the situation he's into and actually fight the triple ko ?

Attachment:
Triple ko.png
Triple ko.png [ 9.25 KiB | Viewed 645 times ]

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 Post subject: Re: strange seki
Post #18 Posted: Thu Oct 29, 2020 3:27 pm 
Oza

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Quote:
With positional superko, a triple ko is exactly the same thing as a simple ko. You need to have enough ko threats in order not to be the one loosing the battle. Why is that bad ?


Who said that was bad? It is the practical complexity of superko that is found to be unacceptable to nearly everyone.

You have a road. You have traffic that wants to travel along that road. So you makes rules. There are alternative rulesets. One ruleset is that everyone drives on the side nearest to the left, as in the UK. Other ruleset stipulates you all drive on the side nearest to the right, as in Europe. In both cases there are also restrictions on overtaking. Both rulesets work. Regrettably a few people do get killed. There are occasional other blips, such as roadworks and lane closures. But people put up with all that and don't change their rules. People even cross the English Channel with their cars and drive under different rulesets, and come home safely!!!!!

Then a mathematician comes along and says we don't need to do that. We can have a supertraffic rule. Everybody can drive and overtake where they like and so can make their journeys faster. It will be supersafe because all they have to do then is be supercareful, which people will be anyway because they don't want to be killed. That's been mathematically proven! This situation does actually exist in some countries, which are usually considered benighted. Next to nobody in the UK or Europe would therefore accept such a new rule, no matter how many supertraffic mathematicians jumped up and down in frustration, and no matter how many seconds of savings on journey times are claimed.

That's hyperbole, of course. But this sort of approach does apply in trivial situations, You see, even in the rather safe confines of a game of go, people - even pros - find it hard to be supercareful. They can't always be sure they play the kos in the right order, especially in fast games. Such mistakes have occurred in pro play. might they want to accuse a professional colleague of making a mistake, or even cheating. No doubt they would also be reluctant to divert a large portion of their earnings to pay for a cadre of referees who will just be called on once in a blue moon when a superko arises. Then you have the problem of whether the referees can stay awake waiting for such a rarity. Unlike major sports that haven't got the finances to install video replays, and no doubt they'd rather not have a digital record of picking their toenails (a la Sakata). In short, they have already decided to make life safe, sane and simple. They ignore superko. Japanese '89 rules are an abomination. OK, they ignore them.

There comes a point in most things in life when it's best if common sense just takes over.

And where common sense does not quite work, no problem: we just apply supercommon sense.

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 Post subject: Re: strange seki
Post #19 Posted: Thu Oct 29, 2020 3:57 pm 
Lives with ko

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Pio2001 wrote:
What's the "real game" ?

Maybe what is played by most players, has closest ties to history and almost all pros agree with (wrt repetition rules)?

Quote:
With positional superko, a triple ko is exactly the same thing as a simple ko. You need to have enough ko threats in order not to be the one loosing the battle. Why is that bad ?

I don't think there is anything wrong with inventing new rules and new variants. But given the wide consensus in Asia wrt triple ko handling, caution and modesty could not hurt either. :)

Besides the issue of applicability, one problem is taking away perfectly legal and desirable moves, forbidding players to defend themselves in some ko shapes. An unnatural and unnecessary change to the game, where the least of such artificial restrictions may be preferred.

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 Post subject: Re: strange seki
Post #20 Posted: Fri Oct 30, 2020 12:08 am 
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John Fairbairn wrote:
It is the practical complexity of superko that is found to be unacceptable to nearly everyone.


Several aspects are involved WRT practical complexity.

1) Practical complexity of identification of repetition: it is similar for superko and void result ko rules because both require recognition of repetition of the whole board position. The latter is a bit relaxed because one need not recognise at / just before the first moment of repetition but players can be dull to recycle several times until both recognise repetition. This raises the additional question why players are supposed to take pride in being dull in a game in which they supposed to be bright.

2) Practical complexity in typical games: in almost all games (4999:5000, 19999:20000 or so), long cycles requiring superko consideration do not even occur so the practical complexity in typical games is extremely low.

3) Understanding why the practical complexity in typical games is extremely low: this requires understanding of the missing practical complexity of superko occurring in these occasional ko situations: sending-2-returning-1; double disturbing death (such as in a big nadare joseki), which, as under other typical ko rulesets such as void ko rules, provides an arbitary supply of ko threats for the dead player.

4) Practical complexity in the relatively most frequent (occurring in, say, 1:5000 or 1:20000 games) superko positions (triple ko or three kos behaving like a triple ko): there is no practical complexity because the ko fight should be exactly like a basic ko fight. There only is slight theoretical complexity, which is much less complex than your typical life and death problem of tactical reading: one must once understand why the ko fight should be exactly like a basic ko fight: due to otherwise occurring repetition, a ko threat sequence in a triple needs to end after, by choice of the ko threat player, 1, 3 or 5 successive plays in the triple ko.

5) Practical complexity in the second-most frequent (occurring in, say, 1:10000 or 1:40000 games) superko positions (quadruple, quintuple ko, moonshine life): now we are entering actual complexity in every one such shape because mindless play can be wrong; the actual move order and moment of next-move repetition matter. However, over all games, the practical complexity is extremely low because of the rarity of such shapes. In go, we take pride in the ability of thinking and in particular tactical reading. Such a rare shape with practical complexity in a game in which it occurs gives the players the chance to demonstrate their skills, which is an advantage compensating the disadvantage of the complexity of procedural handling in such a rare game.

6) Practical complexity in arcane shapes: in theory, superko strategy and tactics can become arbitrarily complex with extremely long cycles or ko fights. In practice, that is, for the sake of practical complexity, such is absolutely immaterial because such shapes (such as molasses ko) never occur (or at worst once in the entire world-wide history of go). Besides, there is the advantage that we have something to celebrate if indeed such a shape occurs.

Quote:
They can't always be sure they play the kos in the right order, especially in fast games.


They also can't always be sure to play non-ko tactics in the right order, so what? Difficult move order in non-long-ko-cycle tactics matters many times per game while difficult move order in long-ko-cycles matters once every 1:10000th or 1:40000th game, so what?

Quote:
Such mistakes have occurred in pro play.


Such mistakes in non-long-ko-cycle tactics in pro plays occur all the time, so what? Prohibit fast games?

Quote:
Then you have the problem of whether the referees can stay awake waiting for such a rarity.


They even have to stay awake for relatively much more frequent incidents, such as self-atari, retracting a move or recapture of a basic ko.

Quote:
Unlike major sports that haven't got the finances to install video replays, and no doubt they'd rather not have a digital record of picking their toenails (a la Sakata). In short, they have already decided to make life safe, sane and simple.


Wrong. That they make referee-handling simpler in 1:5000 or rarer long cycle cases is irrelevant as long as they make referee-handling more difficult in more frequent rules matters, such as not filling the last basic endgame ko.

Quote:
Japanese '89 rules are an abomination. OK, they ignore them.


They ignore parts of them but apply other parts.

Quote:
There comes a point in most things in life when it's best if common sense just takes over.


Common sense like "the simplest, shortest rule text ('a play may not repeat a position') is good enough in practice".

Quote:
And where common sense does not quite work, no problem: we just apply supercommon sense.


Like going back to the position before the start of the long cycle and continue the game from there with carefulness and, if necessary, a few minutes of extra thinking time.

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