Who says AI is territorial? (Joseki reevaluation)

Gérard TAILLE · Post by **Gérard TAILLE** » Sat Feb 24, 2024 3:20 pm

kvasir wrote:
Gérard TAILLE wrote:Maybe I am wrong but what is your own evaluation of the local temperature?
It is one of those cases when it is moderately hard to calculate but knowing if you got the right answer is much harder. So I can calculate for you but it would take too much effort to verify beyond my intuition about what is happening. It is good practice so I'll humor you

I only noted down some numbers but otherwise did it without playing out variations. Since I did this in my head we have to go backwards and I'm not going to explain how I reached the conclusion which I'll try to summarize.

The way I see it, if black takes and wins the ko he is at +17 but if white starts the ko there are two choices. White can choose a big ko to drive up the value per move or a small ko. The thing is that if he chooses the big ko he will forego an endgame move here but if he chooses the small ko he gets that endgame as part of starting the ko.

Most ko are trades, I assume this one is also, therefore I don't want to give up that endgame to drive up the value per move. The small ko then it is.

I have black at +16 if he ends the small ko, I have white at -17 if he ends the same ko. I'll ignore fractions and say the value of the ko will be at +4 when white plays to start it.

How about if black stars a ko immediately? In that case he can win the ko to be at +16 (not sure why I got one less here, I'll just go with it). White, however, can only go back to needing a move to start the small ko.

We, therefore, have a situation of black being able to move to +17 in two moves and white being able to move to +4 in one move. The value of a move in this situation is just 4 or 8 as you like to say

Black won't make a move here for a long time.

OK, OK, I'm ignoring that there is an approach ko but I doubt it is a good idea for black when the situation otherwise isn't urgent. I'm ignoring the approach ko for the reason that white doesn't need to spend an extra move, white in fact gains a move but needs to come up with lot of threats.

There is something important that I have saved for last. Which is the territory in the corner. Since the move was worth ~4 and white were to move to +4 then the territory would seem to be +8 but that is for an arbitrary region. I think we can count some naive +25 points in the corner before white locked-in the aji. Now it is +8, some naive 17 points are already erased. Maybe it is no wonder that the score evaluation is -3 to -4?

It is a little difficult to understand your figures without the corresponding varaitions.
Let me try to show you my result after some more analysis.

Click Here To Show Diagram Code: [go]$$W $$ +--------------------------------------+ $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . O . . . . . . . . . . . . . . .| $$ | . . . , . . . . . , . . . . . X . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . X . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . , . . . . . , . . . . . , O . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . O . .| $$ | . . . . . . . . . . . . . . . X O O .| $$ | . . . O . . . . . . . . . . . X X O .| $$ | . . . . . . . . . . . . . . O X O O X| $$ | . . . O . . . . . , . . . X X O X X b| $$ | . . . . . X . . . . . X X X O O X a O| $$ | . . . . . . . . . . . . . O O . O X .| $$ | . . . . . . . . . . . . . . . O X X .| $$ +--------------------------------------+[/go]

I agree with you. In that position white will probably play first in the corner. I hesitate between white "a" and white "b" but eventually I prefer white "a" because white "b" gives black local ko threats and, should white win the ko, then black should be able to block the white group on the bottom side.

As a consquence I consider that the following sente exchange will take place:

Click Here To Show Diagram Code: [go]$$W $$ +--------------------------------------+ $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . O . . . . . . . . . . . . . . .| $$ | . . . , . . . . . , . . . . . X . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . X . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . , . . . . . , . . . . . , O . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . O . .| $$ | . . . . . . . . . . . . . . . X O O .| $$ | . . . O . . . . . . . . . . . X X O .| $$ | . . . . . . . . . . . . . . O X O O X| $$ | . . . O . . . . . , . . . X X O X X .| $$ | . . . . . X . . . . . X X X O O X 1 O| $$ | . . . . . . . . . . . . . O O 2 O X .| $$ | . . . . . . . . . . . . . . . O X X .| $$ +--------------------------------------+[/go]

Now what is the value of the ko?

If black wins the ko then the result would be

Click Here To Show Diagram Code: [go]$$W $$ +--------------------------------------+ $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . O . . . . . . . . . . . . . . .| $$ | . . . , . . . . . , . . . . . X . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . X . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . , . . . . . , . . . . . , O . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . O . .| $$ | . . . . . . . . . . . . . . . X O O .| $$ | . . . O . . . . . . . . . . . X X O .| $$ | . . . . . . . . . . . . . . O X O O X| $$ | . . . O . . . . . , . . . X X O X X .| $$ | . . . . . X . . . . . X X X O O X O O| $$ | . . . . . . . . . . . . . O O X . X .| $$ | . . . . . . . . . . . . . . X . X X .| $$ +--------------------------------------+[/go]

and we can assume the following endgame

Click Here To Show Diagram Code: [go]$$W $$ +--------------------------------------+ $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . O . . . . . . . . . . . . . . .| $$ | . . . , . . . . . , . . . . . X . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . X . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . , . . . . . , . . . . . , O . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . O . .| $$ | . . . . . . . . . . . . . . . X O O .| $$ | . . . O . . . . . . . . . . . X X O 1| $$ | . . . . . . . . . . . . . . O X O O 4| $$ | . . . O . . . . . , . . . X X O X X 3| $$ | . . . . . X . . . . . X X X O O X O O| $$ | . . . . . . . . . . . . . O O X . X 2| $$ | . . . . . . . . . . . . . . X . X X .| $$ +--------------------------------------+[/go]

Click Here To Show Diagram Code: [go]$$W $$ +--------------------------------------+ $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . O . . . . . . . . . . . . . . .| $$ | . . . , . . . . . , . . . . . X . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . X . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . , . . . . . , . . . . . , O . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . O . .| $$ | . . . . . . . . . . . . . . . X O O .| $$ | . . . O . . . . . . . . . . . X X O O| $$ | . . . . . . . . . . . . . . O X O O 7| $$ | . . . O . . . . . , . . . X X O X X 5| $$ | . . . . . X . . . . . X X X O O X . 6| $$ | . . . . . . . . . . . . . O O X . X X| $$ | . . . . . . . . . . . . . . X . X X .| $$ +--------------------------------------+[/go]

If white wins the ko then the result would be

Click Here To Show Diagram Code: [go]$$W $$ +--------------------------------------+ $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . O . . . . . . . . . . . . . . .| $$ | . . . , . . . . . , . . . . . X . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . X . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . , . . . . . , . . . . . , O . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . O . .| $$ | . . . . . . . . . . . . . . . X O O .| $$ | . . . O . . . . . . . . . . . X X O .| $$ | . . . . . . . . . . . . . . O X O O X| $$ | . . . O . . . . . , . . . X X O . . O| $$ | . . . . . X . . . . . X X X O O . O O| $$ | . . . . . . . . . a . . . O O . O X .| $$ | . . . . . . . . . . . . . . . O X X .| $$ +--------------------------------------+[/go]

Here the evaluation of the result on the lower side is not easy : in the middle game the white invasion at "a" threatens a connection and in the endgame, depending on the exact configuration reached white will be able to play in sente an ogeima or a keima.
Assuming simply that white will be able to play the ogeima in sente then the final result will be

Click Here To Show Diagram Code: [go]$$W $$ +--------------------------------------+ $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . O . . . . . . . . . . . . . . .| $$ | . . . , . . . . . , . . . . . X . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . X . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . , . . . . . , . . . . . , O . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . O . .| $$ | . . . . . . . . . . . . . . . X O O .| $$ | . . . O . . . . . . . . . . . X X O .| $$ | . . . . . . . . . . . . . . O X O O X| $$ | . . . O . . . . . , . . . X X O . . O| $$ | . . . . . X . . . . . X X X O O . O O| $$ | . . . . . . . . . X X X O O O . O X .| $$ | . . . . . . . . . X O O O . . O X X .| $$ +--------------------------------------+[/go]

Finally considering the area marked here under

Click Here To Show Diagram Code: [go]$$W $$ +--------------------------------------+ $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . O . . . . . . . . . . . . . . .| $$ | . . . , . . . . . , . . . . . X . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . X . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . , . . . . . , . . . . . , O . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . O . .| $$ | . . . . . . . . . . . . . . . X O O .| $$ | . . . O . . . . . . . . . . . X X O P| $$ | . . . . . . . . . . . . . . O X O O Z| $$ | . . . O . . . . . , . . . X X P Z Z P| $$ | . . . . . X . . . . . X X X P P Z M P| $$ | . . . . . . . . . M M M M P P Z P Z M| $$ | . . . . . . . . . M M M M M M P Z Z M| $$ +--------------------------------------+[/go]

If I am not wrong:
if black wins the ko then B+26
if white wins the ko then B-20
The swing value of the ko is 46 and the miai value is about 15 points.
After the first sente exchange black has taken the ko => the count of the position B+11 (26 - 15).

kvasir · Post by **kvasir** » Sun Feb 25, 2024 11:23 am

Gérard TAILLE wrote:It is a little difficult to understand your figures without the corresponding varaitions.
Let me try to show you my result after some more analysis.

I can see if I can add diagrams later but I'm not sure it is so interesting for me

Your analysis is similar to mine but I'm suspicious of choosing the larger ko and not assuming that white is playing it to win. Possible the difference between these two ko isn't enough to make a difference. I mean that it is possible white also shouldn't play the smaller ko unless he means to guarantee that he wins the ko and in that case it is likely better to win the larger ko. My point was about that black should or could wait for white to start the ko, for now. Black appears to gain a move if white plays first in the corner. White would after all be playing two moves in a row in the corner.

Click Here To Show Diagram Code: [go]$$B Black plays away, white has choice between a larger ko with A and a smaller one with B, and of course tenuki. $$ +--------------------------------------+ $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . O . . . . . . . . . . . . . . .| $$ | . . . , . . . . . , . . . . . X . . .| $$ | . . X . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . X . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . , . . . . . , . . . . . , O . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . O . .| $$ | . . . . . . . . . . . . . . . X O O .| $$ | . . . O . . . . . . . . . . . X X O .| $$ | . . . . . . . . . . . . . . O X O O X| $$ | . . . O . . . . . , . . . X X O X X b| $$ | . . . . . X . . . . . X X X O O X a O| $$ | . . . . . . . . . . . . . O O . O X .| $$ | . . . . . . . . . . . . . . . O X X .| $$ +--------------------------------------+[/go]

We both used the method of finding a value for the ko and value per move but the calculus would change if we assume one or the other player could win the ko using good threats. I think white is close to being there, maybe he could win the ko. I did assume that white can't guarantee this outcome and is interested in a fair trade. Possibly this assumption is not good but it was what I thought was a reasonable assumption but these ko are large

It still seems likely to me that black shouldn't play first in the corner. They say every dog has its day, but usually you can't make up for playing more moves when less would have done. Without checking the principle variation that KataGo provides I can only guess at what happens if white tries to win the large ko.

Now that the questions have become so complicated I have began to wonder what KataGo says. I looked at it briefly before and recall that these questions weren't critical. Now that I'm checking again it appears they are even less critical than what I recalled.

Gérard TAILLE · Post by **Gérard TAILLE** » Sun Feb 25, 2024 2:01 pm

kvasir wrote:
Gérard TAILLE wrote:It is a little difficult to understand your figures without the corresponding varaitions.
Let me try to show you my result after some more analysis.
I can see if I can add diagrams later but I'm not sure it is so interesting for me

Your analysis is similar to mine but I'm suspicious of choosing the larger ko and not assuming that white is playing it to win. Possible the difference between these two ko isn't enough to make a difference. I mean that it is possible white also shouldn't play the smaller ko unless he means to guarantee that he wins the ko and in that case it is likely better to win the larger ko. My point was about that black should or could wait for white to start the ko, for now. Black appears to gain a move if white plays first in the corner. White would after all be playing two moves in a row in the corner.

$$B Black plays away, white has choice between a larger ko with A and a smaller one with B, and of course tenuki. $$ +--------------------------------------+ $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . O . . . . . . . . . . . . . . .| $$ | . . . , . . . . . , . . . . . X . . .| $$ | . . X . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . X . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . , . . . . . , . . . . . , O . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . O . .| $$ | . . . . . . . . . . . . . . . X O O .| $$ | . . . O . . . . . . . . . . . X X O .| $$ | . . . . . . . . . . . . . . O X O O X| $$ | . . . O . . . . . , . . . X X O X X b| $$ | . . . . . X . . . . . X X X O O X a O| $$ | . . . . . . . . . . . . . O O . O X .| $$ | . . . . . . . . . . . . . . . O X X .| $$ +--------------------------------------+
Click Here To Show Diagram Code
[go]$$B Black plays away, white has choice between a larger ko with A and a smaller one with B, and of course tenuki. $$ +--------------------------------------+ $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . O . . . . . . . . . . . . . . .| $$ | . . . , . . . . . , . . . . . X . . .| $$ | . . X . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . X . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . , . . . . . , . . . . . , O . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . O . .| $$ | . . . . . . . . . . . . . . . X O O .| $$ | . . . O . . . . . . . . . . . X X O .| $$ | . . . . . . . . . . . . . . O X O O X| $$ | . . . O . . . . . , . . . X X O X X b| $$ | . . . . . X . . . . . X X X O O X a O| $$ | . . . . . . . . . . . . . O O . O X .| $$ | . . . . . . . . . . . . . . . O X X .| $$ +--------------------------------------+[/go]
We both used the method of finding a value for the ko and value per move but the calculus would change if we assume one or the other player could win the ko using good threats. I think white is close to being there, maybe he could win the ko. I did assume that white can't guarantee this outcome and is interested in a fair trade. Possibly this assumption is not good but it was what I thought was a reasonable assumption but these ko are large

It still seems likely to me that black shouldn't play first in the corner. They say every dog has its day, but usually you can't make up for playing more moves when less would have done. Without checking the principle variation that KataGo provides I can only guess at what happens if white tries to win the large ko.

Now that the questions have become so complicated I have began to wonder what KataGo says. I looked at it briefly before and recall that these questions weren't critical. Now that I'm checking again it appears they are even less critical than what I recalled.

I agree with you kvasir.
Remember what I said in my post https://lifein19x19.com/viewtopic.php?p=280202#p280202 :
My expectation is the following. White will start the ko very soon and will probably win the ko and kill black group in the corner. In exchange black will be able to play tenuki two times. If the ambiant temperature is equal to 13 that means that black can consider he has 26 ( 2 * 13) points in the corner.

Let's expect that white will be able to play first in the corner and will be able to win the ko.
The question is now the following: when white will start the ko?
The question is difficult indeed. If the ambiant temperature is T then, in compensation for the corner killed by white, black will play tenuki two times and will gain 2*T points. That means that white wish to wait for a ambiant temperature as low as possible. In the other hand, if white wait too long then her good ko threats could disappear and black could also build her own ko threats.
In addition, if white wait too long then a difficult fight may take place elsewhere on the board and the temperature could stay quite high.
For those reasons I think white should start the ko quite early in order to win this ko and let black play tenuki two times.

kvasir · Post by **kvasir** » Thu Feb 29, 2024 3:06 pm

Gérard TAILLE wrote:Let's expect that white will be able to play first in the corner and will be able to win the ko.
The question is now the following: when white will start the ko?
The question is difficult indeed. If the ambiant temperature is T then, in compensation for the corner killed by white, black will play tenuki two times and will gain 2*T points. That means that white wish to wait for a ambiant temperature as low as possible. In the other hand, if white wait too long then her good ko threats could disappear and black could also build her own ko threats.
In addition, if white wait too long then a difficult fight may take place elsewhere on the board and the temperature could stay quite high.
For those reasons I think white should start the ko quite early in order to win this ko and let black play tenuki two times.

It is not only a difficult question, it's a question that starts from lot of assumptions.

I'm very suspicious about arguments that start by declaring something like "white will win every ko". If you assume this, then ko becomes a one sided move that black can't play. If you state instead "white will win every ko while <some-condition> is true", then there is still a very strong assumption there.

Why not instead assume the player that starts the ko wins it? Possibly by ignoring a ko threat. When we do this we would eliminate capturing in the ko on the two conditions:

If winning the ko in this way is not better than other moves in the game. We'd say it's dominated by some other move.
If winning the ko ends up being worse than letting the other player play. We'd say it is reversed.

It is not clear which of these condition applies when we say that white will win the ko. Maybe that is why it appears as if white's fortunes could suddenly change if few moves later we say that black will win the ko? I can't relate this argument directly to this complex position but I think it is likely that if starting the ko immediately isn't white's strategic choice, then the change in who we say is winning the ko is somewhat fictious.

Take for example a gote endgame move. What happens if we declare white will play this move and then declare a few moves later that black will play there? We can often make good arguments about who is likely to play an endgame move. In this case nothing really happened unless either player made a mistake, our argument about who will play first might help us identify some mistakes but it isn't an assumption that we strictly require. It is also an argument that can lead us astray if we turn it into an assumption.

At the risk of relativize the argument one can also ask what happened in this case if it was never part of white's strategy to be certain about who wins this ko? In this position it doesn't seem reasonable to claim to know what the optimal strategy is or to claim that we could discover it. I think we need to be very careful when optimal strategy is so subtle.

I ran KataGo for 1 million playout on the four most interesting candidates. For some reason the playout statistics sums to a higher number in the following screenshots but it was the same 1 million in each case. Take a look at the attached image.

Gérard TAILLE · Post by **Gérard TAILLE** » Fri Mar 01, 2024 9:22 am

kvasir wrote:
Gérard TAILLE wrote:Let's expect that white will be able to play first in the corner and will be able to win the ko.
The question is now the following: when white will start the ko?
The question is difficult indeed. If the ambiant temperature is T then, in compensation for the corner killed by white, black will play tenuki two times and will gain 2*T points. That means that white wish to wait for a ambiant temperature as low as possible. In the other hand, if white wait too long then her good ko threats could disappear and black could also build her own ko threats.
In addition, if white wait too long then a difficult fight may take place elsewhere on the board and the temperature could stay quite high.
For those reasons I think white should start the ko quite early in order to win this ko and let black play tenuki two times.
It is not only a difficult question, it's a question that starts from lot of assumptions.

I'm very suspicious about arguments that start by declaring something like "white will win every ko". If you assume this, then ko becomes a one sided move that black can't play. If you state instead "white will win every ko while <some-condition> is true", then there is still a very strong assumption there.

Why not instead assume the player that starts the ko wins it? Possibly by ignoring a ko threat. When we do this we would eliminate capturing in the ko on the two conditions:

If winning the ko in this way is not better than other moves in the game. We'd say it's dominated by some other move.

If winning the ko ends up being worse than letting the other player play. We'd say it is reversed.

It is not clear which of these condition applies when we say that white will win the ko. Maybe that is why it appears as if white's fortunes could suddenly change if few moves later we say that black will win the ko? I can't relate this argument directly to this complex position but I think it is likely that if starting the ko immediately isn't white's strategic choice, then the change in who we say is winning the ko is somewhat fictious.

Take for example a gote endgame move. What happens if we declare white will play this move and then declare a few moves later that black will play there? We can often make good arguments about who is likely to play an endgame move. In this case nothing really happened unless either player made a mistake, our argument about who will play first might help us identify some mistakes but it isn't an assumption that we strictly require. It is also an argument that can lead us astray if we turn it into an assumption.

At the risk of relativize the argument one can also ask what happened in this case if it was never part of white's strategy to be certain about who wins this ko? In this position it doesn't seem reasonable to claim to know what the optimal strategy is or to claim that we could discover it. I think we need to be very careful when optimal strategy is so subtle.

I ran KataGo for 1 million playout on the four most interesting candidates. For some reason the playout statistics sums to a higher number in the following screenshots but it was the same 1 million in each case. Take a look at the attached image.

Seeing your post it appears that the move

here after is part of top moves for black.

Click Here To Show Diagram Code: [go]$$B $$ +--------------------------------------+ $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . O . . . . . . . . . . . . . . .| $$ | . . . , . . . . . , . . . . . X . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . X . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . , . . . . . , . . . . . , O . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . O . .| $$ | . . . . . . . . . . . . . . . X O O .| $$ | . . . O . . . . . . . . . . . X X O .| $$ | . . . . . . . . . . . . . . O X O O X| $$ | . . . O . . . . . , . . . X X O X X .| $$ | . . . . . X . . . . . X X X O O X . O| $$ | . . . . . . . . . . . . . O O 1 O X .| $$ | . . . . . . . . . . . . . . . O X X .| $$ +--------------------------------------+[/go]

We previously concluded that it was not a good idea for black to play first in the bottom left corner. Does that mean that something was wrong in our analysis? I believed that the value of this black move was far smaller than 15 but it must be wrong. How do you calculate such value (without trying to be very accurate OC)?

Gérard TAILLE · Post by **Gérard TAILLE** » Fri Mar 01, 2024 2:55 pm

Click Here To Show Diagram Code: [go]$$B $$ +--------------------------------------+ $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . O . . . . . . . . . . . . . . .| $$ | . . . , . . . . . , . . . . . X . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . X . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . , . . . . . , . . . . . , O . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . O . .| $$ | . . . . . . . . . . . . . . . X O O .| $$ | . . . O . . . . . . . . . . . X X O .| $$ | . . . . . . . . . . . . . . O X O O X| $$ | . . . O . . . . . , . . . X X O X X .| $$ | . . . . . X . . . . . X X X O O X b O| $$ | . . . . . . . . . . . . . O O a O X .| $$ | . . . . . . . . . . . . . . . O X X .| $$ +--------------------------------------+[/go]

After having analysed the position in the botoom right corner, assuming neither player has a ko threat available, I concluded that a black move at "a" as well as a white move at "b" is valued 15 points. At least it is consistant with top moves according to katago. In addition I think the count of this position is B+30.
In pratice I expect one of the player will very soon play in this corner.

kvasir · Post by **kvasir** » Sat Mar 02, 2024 3:24 am

Gérard TAILLE wrote:Seeing your post it appears that the move here after is part of top moves for black

There is very little difference in the evaluation of the top four or so moves. Approaching the corner in the top left has better score and percentage evaluation than playing in the ko position in the lower right. The difference is only about 2 / 5 of a point.

I'll come back to why I think the obvious big approach moves and the ko situation have similar evaluaion.

Gérard TAILLE wrote:We previously concluded that it was not a good idea for black to play first in the bottom left corner. Does that mean that something was wrong in our analysis? I believed that the value of this black move was far smaller than 15 but it must be wrong. How do you calculate such value (without trying to be very accurate OC)?

Our analysis was probably quite good, I think our conclusion was that it isn't necessary to start the ko immediately and you can see in the screenshots, I posted previously, how this is confirmed by KataGo. I might have analyzed the approach ko incorrectly, maybe I didn't count the moves right, I'm really not sure. I was mainly trying to give reasons why playing the ko wasn't necessary (that means right away, it will have to be resolved somehow eventually). We can't expect to get exact results by only counting points in the opening and therefore shouldn't be very concerned if that part of the analysis has shortcomings.

How to calculate this ko? Well, it really is complicated by there being many different possible ko. I think some feeling for which ko is the right one is necessary. Personally, I think I might have a better chance of picking the right ko based on my mood than on a detailed analysis. Here the principle is that the larger ko is more worthwhile for white, if it can be fought but white has local threats so this proofs to be possible, and that white has the privilege to start the ko, which means that the conditions for playing first in the ko are materialized earlier for white than black. When it comes to evaluating the ko then it is most important if it is heavy or not, this ko isn't heavy, black and white have pretty much the same size of territory at stake. The score has already shifted to match the fact that there is this ko in the corner; it is a sunk cost so to speak for black who might have expected to own the whole corner. That was a guide of some sort, at least it's the insights that I think are important to evaluate the ko.

When I try to evaluate the ko more formally I find that I have difficulty evaluating the step ko that white actually shouldn't play and I have difficulty keeping track of the structure of this very complex position. These two things mean that a more formal evaluation isn't really possible for me, unless I take the structure of the position as something given (i.e. which ko to play, eliminate alternatives and decide what will be sente ahead of the analysis) which then isn't much of an analysis after all.

One thing that I found when I did try, and this could be due to my mistakes, was that the ko position is a "number". That is, it is a position which both players can avoid playing in. I say this could be due to my mistake but it also makes sense that the position would at least be equitable, or close to so, if the conclusion was that the players could (and should) avoid playing in it, but this could of course be my bad arithmetic. For one thing it does fail one sanity check, which is that the other ko would seem to no give a number and white appeared to prefer it. However, that could be due to me simply mixing up all the temperatures.

Gérard TAILLE wrote:After having analysed the position in the botoom right corner, assuming neither player has a ko threat available, I concluded that a black move at "a" as well as a white move at "b" is valued 15 points. At least it is consistant with top moves according to katago. In addition I think the count of this position is B+30.
In pratice I expect one of the player will very soon play in this corner.

I think after white plays "b" the value per move is about 15 points, I got 15 7/9 for what that is worth. On the other hand it appears to me that black playing "a" would be a move in a game that is a number

OK, we take he ko first if white has to find a ko threat and at some point this ko will dominate the game but I think it is better to not play in the ko until we have to. "a" in this sense has a negative value, like any move in a number like for example in a seki. The reason it is a number is that black is better off if he waits for white to start the ko.

BTW I played from this position, using moves as indicated by KataGo for 77 moves before playing in the ko was the only move

At a few points I had to let KaTrain look for alternative moves when playing in he ko was indicated but I think most of the time the alternatives where either better (in terms of score) or it was just about splitting hairs, but, yes, I tried to avoid playing in the ko.

Maybe we need a topic for ko fun

Gérard TAILLE · Post by **Gérard TAILLE** » Sat Mar 02, 2024 11:59 am

kvasir wrote: One thing that I found when I did try, and this could be due to my mistakes, was that the ko position is a "number". That is, it is a position which both players can avoid playing in. I say this could be due to my mistake but it also makes sense that the position would at least be equitable, or close to so, if the conclusion was that the players could (and should) avoid playing in it, but this could of course be my bad arithmetic. For one thing it does fail one sanity check, which is that the other ko would seem to no give a number and white appeared to prefer it. However, that could be due to me simply mixing up all the temperatures.

Click Here To Show Diagram Code: [go]$$B $$ +--------------------------------------+ $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . O . . . . . . . . . . . . . . .| $$ | . . . , . . . . . , . . . . . X . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . X . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . , . . . . . , . . . . . , O . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . . O . .| $$ | . . . . . . . . . . . . . . . X O O .| $$ | . . . O . . . . . . . . . . . X X O .| $$ | . . . . . . . . . . . . . . O X O O X| $$ | . . . O . . . . . , . . . X X O X X a| $$ | . . . . . X . . . . . X X X O O X . O| $$ | . . . . . . . . . . . . . O O X . X .| $$ | . . . . . . . . . . . . . . . O X X .| $$ +--------------------------------------+[/go]

After black capture the ko I do not really see a "number". I believe white will be able to play "a" in sente. Instead, should black play herself this "a" then black will gain 5 points in gote.

I tried to calculate a new evaluation assuming white has only one ko threat at "a" in the following diagram:

Click Here To Show Diagram Code: [go]$$Bc Black to play $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . , . . . . . , . . . . . , O . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . a O . .| $$ | . . . . . . . . . . . . . . . X O O .| $$ | . . . . . . . . . . . . . . . X X O .| $$ | . . . . . . . . . . . . . . O X O O X| $$ | . . . . . . . . . , . . . X X O X X .| $$ | . . . . . . . . . . . X X X O O X . O| $$ | . . . . . . . . . . . . . O O . O X .| $$ | . . . . . . . . . . . . . . . O X X .| $$ +--------------------------------------+[/go]

Two main cases:
1)

tenuki and white starts the ko and wins it:

Click Here To Show Diagram Code: [go]$$Bc :b1: and :b7: tenuki $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . , . . . . . , . . . . . , O . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . 4 O . .| $$ | . . . . . . . . . . . . . . 5 X O O .| $$ | . . . . . . . . . . . . . . . X X O .| $$ | . . . . . . . . . . . . . . O X O O X| $$ | . . . . . . . . . , . . . X X O X X 8| $$ | . . . . . . . . . . . X X X O O X 2 O| $$ | . . . . . . . . . . . . . O O 3 6 X .| $$ | . . . . . . . . . . . . . . . O X X .| $$ +--------------------------------------+[/go]

count = -20 + 2T

2)

takes immediatetly the ko

Click Here To Show Diagram Code: [go]$$Bc :w2: tenuki $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . , . . . . . , . . . . . , O . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . a O . .| $$ | . . . . . . . . . . . . . . . X O O .| $$ | . . . . . . . . . . . . . . . X X O .| $$ | . . . . . . . . . . . . . . O X O O X| $$ | . . . . . . . . . , . . . X X O X X a| $$ | . . . . . . . . . . . X X X O O X . O| $$ | . . . . . . . . . . . . . O O 1 O X .| $$ | . . . . . . . . . . . . . . . O X X .| $$ +--------------------------------------+[/go]

and I assume white while play "a" in sente to reach the following final position

Click Here To Show Diagram Code: [go]$$B $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . , . . . . . , . . . . . , O . .| $$ | . . . . . . . . . . . . . . . . . . .| $$ | . . . . . . . . . . . . . . . a O . .| $$ | . . . . . . . . . . . . . . . X O O .| $$ | . . . . . . . . . . . . . . . X X O O| $$ | . . . . . . . . . . . . . . O X O O O| $$ | . . . . . . . . . , . . . X X O X X O| $$ | . . . . . . . . . . . X X X O O X X O| $$ | . . . . . . . . . . . . . O O X . X X| $$ | . . . . . . . . . . . . . . X . X X .| $$ +--------------------------------------+[/go]

count = +23-T
Compararing the two cases above I think the local temperature (assuming one ko threat for white) is t = (23+20)/3 = 14.33
Considering your long 77 moves sequence it is not inconsistent because in your sequence the ambiant temperature seems always relatively high.

Life In 19x19

Who says AI is territorial? (Joseki reevaluation)

Re: Who says AI is territorial? (Joseki reevaluation)

Re: Who says AI is territorial? (Joseki reevaluation)

Re: Who says AI is territorial? (Joseki reevaluation)

Re: Who says AI is territorial? (Joseki reevaluation)

Re: Who says AI is territorial? (Joseki reevaluation)

Re: Who says AI is territorial? (Joseki reevaluation)

Re: Who says AI is territorial? (Joseki reevaluation)

Re: Who says AI is territorial? (Joseki reevaluation)