Stones are said to be "alive " if they cannot be captured by the opponent, or if capturing them would enable a new stone to be played that the opponent could not capture.
The argument is that white is alive because capturing them enables white to play a new stone that black cannot capture:
Alternatively, if white’s new enabled stone needs to be on a spot on the board that they didn’t already have a stone placed, then we would have some tactics as white tries to kill black’s stone and hopefully live in a way that they can fill their own stone on the 1-1 point. (But I would think that this isn’t required? Surely there is some other case of some under-the-stones resulting in the enables-a-new-stone dictating that something is alive).
Since the examples contradict tradition severely, the concept of enable is a failure in itself.
If you are aiming for the most accurate implementation of literal Japanese rules in KataGo, including situations like this, it’s probably not worth it.
What about the further examples provided under " 1. Positions Related to Article 7, Clause 1" in the second commentary addendum “Examples of Confirmation of Life and Death”?
That part gives several other examples that seem to imply that this “enable” clause applies more broadly than just snapbacks.
For example, I think this given position (among others) establishes the generality of this enabling concept:
If you look further down the page you link to, you will see an explanation that this specifically refers to snapbacks.
Ah okay just scrolled down and now I understand that it’s referring to snapbacks. Though it’s a terrible way to describe snapbacks. And the concept of snapbacks is a bit different from the concept of eyes.
Thank you for finding a position which is more subtle position than it looks!
If it’s White’s turn, White cannot play any move, so cannot continue the game and place new stones and build new territories.
If it’s Black’s turn, it is clear that Black can capture White, but if Black does play a move to capture White, then Black will give White the opportunity to play new stones and create new groups and build new territories.
Under Chinese rules for instance, if both players pass in this position, then it is in White’s interest to argue that the White group is alive, so that Black is forced to resume the game and actually capture it, which gives White the opportunity to keep playing.
In my opinion and interpretation of the rules, yes.
I think the clause as written and the various commentary examples support this interpretation.
With any highly pathological rules beasts, there is ultimately the gold standard of how it would actually be judged by Japanese Go association officials, if it had somehow occurred in a real professional game. However, I think the Nihon Ki-in are somewhat constrained and they would have to create some sort of special new interpretation of this enabling concept to handle this case, if they were to rule that the position is dead.
A hairy aspect of this sort of rule and interpretation is that it allows the embedding all sort of arbitrary and intractable life/death questions into the considerations of hypothetical play (however, I guess, broadly speaking, that is already the case with respect all sorts of other rules beasts one could construct to test the limits of life/death determination via ideal hypothetical play).
The example given the original post has most of the board being cleared by the hypothetical capture, and I think it is fairly “obvious” and would be widely accepted that White is in fact able to establish a living group in the new space.
However, one could make the vacated space take an arbitrary size and shape. For example, one could have the shape game as the position hypothetically left behind after the White stones have been hypothetically captured:
Thus, the question of whether the White stones are alive boils down to answering whether or not White could create a living group in the shape game.
Or imagine that the space vacated is a N-by-N square in the corner, surrounded by unconditionally alive Black stones. It’s not clear what size N needs to be to say that White could hypothetically live with an invasion.
See: When is 3-3 alive?
Under Japanese rules, black taking the stones would have gained so many prisoners, so either way black would win.
I understand what you mean. But anyway the situation you described seems to be a different issue than what is described by that sentence in the rules. In the elaboration further down, it is elaborated that the sentence is referring to snapbacks.
As I mentioned above, there are further examples in the second commentary that seem to establish that the enable clause applies more broadly than just to snapbacks.
There are 349 white stones and 9 Black stones on that board. Presumably White has about 340 prisoners already.
So Black would only be 9 points ahead in prisoners by capturing the White group, plus 2 points of territory at S7 and T8, minus 6.5 points of komi. Black’s strongest advantage wouldn’t be the points of prisoners, it would be the strong influence provided by having the small unconditionally-alive group on the side.
Still, White has a chance if Black makes the capturing move, but no chance if Black can claim that the White stones are dead without actually capturing them.
Lol there will be no end if we are going to talk about how this shape came out in the first place. Who knows maybe Black played 9 moves and passed 340 moves, leaving white to fill up his own territory.
Ah sorry I didn’t see that. Still, I think that the example in the diagram you gave is a different case. It’s not that the 2 stones are alive because black plays two moves that cannot be captured. It’s just that eating the 2 stones is not beneficial for white since it doesn’t help white gain points. It’s different from the snapback situation where you can eat one stone but your group still gets eaten back.
In the extreme case that white needs a ko threat, white can still choose to “kill” the 2 stones. But in a snapback the particular stone will always be alive.
It’s hard to be sure how a Japanese pro referee would judge this, but I’d expect that to match general TS logic here: W is alive (with a stronger claim than the single stone in the official torazu3 example! (L/D ex. 1)). This simply looks a partial snapback/nakade, and enable works correctly.
It could be argued that “partial” should not be enough, or that W not necessarily captures any B stones by snapping back (depending on shape). But I think the logic is the opposite: only 100% clean captures are granted for free. Doubtful or partial cases are alive, unclean captures (with any negative consequences) need to be played out in actual game. J89 dia 16 shows a true dead stone and 100% clean capture. W above is different - not just passive stones in B territory.
And J89 specifics aside, a strong theoretical approach is that a region is your territory ONLY if you have it surrounded, and can take pass-alive control of it (without giving up anything in exchange). Territory scoring doesn’t really need L/D - and again W is not in B territory so not removed.
The purpose of the diagram that I shared is to illustrate that the “enable clause” applies beyond just snapback situations. Of course, there are other examples also given alongside in that part of the commentary that illustrates other cases of the “enable clause” being applied in situations that don’t involve a snapback.
No, I think the point of this example in the commentary is precisely to clarify that the 2 Black stones in the corner are considered alive, specifically because hypothetical play by White to capture those stones would enable Black to play more stones that cannot be captured.
The text explicitly states:
Reason why the two black stones are alive:
If White captures Black’s two stones, Black can play two new stones (at 2 and 4) which White cannot capture.
The “enable clause” is important here since it allows the following position to be considered settled as a seki, without requiring Black to throw-in another prisoner at either A or the point above:
The commentary is pointing out that without the “enable clause”, White could argue that the two Black stones are dead under hypothetical play. Even though White would lose two other stones under the hypothetical line, it still proves that those two Black stones in the corner are dead.
Reason why the two black stones are alive:
If White captures Black’s two stones, Black can play two new stones (at 2 and 4) which White cannot capture.
In this example, after white takes the 2 black stones in the corner, they are considered dead, right?
And this is a result that may happen in a real game. White can totally use 1 as a ko threat. White didn’t lose any points in this variation but didn’t gain any either.
I think the argument of whether this group is a seki or not is a different argument from whether the corner 2 black stones are alive or not. Also it seems kind of a trivial matter to argue whether the 2 black stones are alive in this case.
