Do you mean something like sending-2-returning-1 ?
If so then it wouldn't prevent the opponent to play a capture sequence elsewhere. As far I can see the only problem this can cause is that the hypo-sequence doesn't end with two passes.

You need not count removed stones, but it suffices to count passes and detect if a cycle is positional / situational:

http://senseis.xmp.net/?CycleLaw

According to Martin Stiassny in Deutsche Go-Zeitung 5/2013, the 4th Asian Indoor & Martial Arts Games Incheon 2013 were the first such event with Go. Hence, for earlier such events, one need not clarify which Go rules they might have used: none.

I've looked at his webpage but couldn't find this example. However I'm not sure if I understand correctly what you mean with "seki shape without neutral points" so maybe I just couldn't identify that shape.
Can you show (a link to) that example or explain the principle, please?

See http://www.suomigo.net/wiki/KimuranttiAsema.

Interesting position. Thank you for the link!

When both really pass there:

In J1989 all w stones should be dead (imo), no matter if b already has a stone at 'a'.

In Asian Game Rules 2013 (though I need to study this rules more) I'd say without a b stone at 'a' its 4-4 points, but with a b stone at 'a' I'd say it's 5-4 points in w favor.

I know. In J1989 rules white should throw in a stone and give up one point to save the situation.

I see. Cannot understand what you have written there, but because of the link to j2003 I guess it's related to that rule.

Hello, asura,

In another context, I had to think about this example again.

Now, I am afraid that the result, which is given in the official commentary, is not correct, at least it is not consistent within the given environment.

The official comment does not mention the single White stone, but White's four-stone group alone.
It is true that White's four-stone group cannot be captured during the long-life cycle, started by Black's Atari on the first line.

However, White's single stone on the right becomes captured every fourth move, so White will be unable to establish a permanent stone on this point. It follows that this stone cannot be called "unconditionally alive".

Black's ten-stone group is not completely surrounded by White stones that are "unconditionally alive", so it may be "dead", but must not be taken off the board at the end of the game. The whole position will become a Seki !!!

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

I remember I made the same thinking once.
However here the commentary is right, because when the four white stones get analysed the single w stone does not matter at all.
The single w stone needs its own analysis: There are two possibilities:
1) If b plays at 'a' then w can give up the 4 stones and captures the single b stone (and the single w stone is alive).
2) If b captures the single w stone directly then w plays 'a' and all b stones will die.

I'm late to the discussion, but this doesn't necessarily need to be an error. There is no problem with that group having 8 liberties (instead of what you would traditionally think of as 7). The only distinction in the rules where liberties are pertinent are moves that fill the last liberty, and all of those still apply. Admittedly, the examples they give that describe "two compartmentalized liberties" would be in error, but upon my first reading, I don't see an issue that would crop up from this definition.

Thanks a lot !

This seems to be a very common oversight, even by professional authors

I remember that I once knew this effect, so it seems that I forgot about it in the meantime ...

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

Yea, I wonder if they were really aware of this or if it's just luck that it works

I have made a slight variation here.



I have made the number of stones equal, and given Black only three points of territory.

This is certainly no seki under area scoring, under which the kos should be resolved, or White will win by one point on the board. But under territory scoring which does not count points in seki, it should in theory be considered a seki. Whichever player initiates play in it loses one point in gote.

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

Visualize whirled peas.

Everything with love. Stay safe.

You are missing the point, Bill.

Under the Nihon Kiin rules (J1989), White's large group in the centre cannot be taken off the board, so it is "alive".

It has no Dame, so it contains territory.

With your position shown, White wins the game by one point.

Black must resolve one of the Seki (either in the top left, or the lower left, corner) to win the game, as shown in your sequences.

+ + + + + + + + + +

In my opinion, Robert's link to the presentation of the original position had an inappropriate headline.

The main topic is NOT "Seki without Dame", but a living group that has one eye only.

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

I wouldn't call it seki without dame, too. The main point is that there are (hidden) kos.
Some time ago I made a position that is related to that but the kos are obvious. But here all white stones are dead in J1989. (Of corse its a mistake for w to pass.)

It is one point better for black to start inside white's big eye.

Well, I guess I am dense this morning. inside the eye. passes. Now what?

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

Visualize whirled peas.

Everything with love. Stay safe.

Perhaps White got an additional prisoner for free ?

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

That's the reason I said in theory.

This is similar to Three Points without Capturing, based upon a ruling by Honinbo Shuwa (IIRC), which is worth only two points under J89. I think that Shuwa was right, and would rule this a seki (or zero points, anyway).

Besides, are you sure that that group is alive under hypothetical play? White can throw in to make a ko, which Black takes, and then if White passes for that ko, Black simply wins the ko. If White throws in to make another ko, Black takes it, as well. Now whichever ko White passes for, Black wins.

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

Visualize whirled peas.

Everything with love. Stay safe.