This 'n' that

[Uberdude]

jlt, hopefully this makes Bill's point clearer. Which of these boards is better for black (under usual endgame assumption that outside stones alive and rest of board dame, so I'm not asking about value of the big walls)?

$$B
$$ -------------
$$ . X O O . O .
$$ . X X X X O .
$$ . . . . . O .
$$ . X O O , O .
$$ . X X X X O .
$$ . . . . . O .
$$ . X O O . O .
$$ . X X X X O .
$$ . . . . . O .
$$ . X O O , O .
$$ . X X X X O .
$$ . . . . . . .

Click Here To Show Diagram Code

[go]$$B
$$ -------------
$$ . X O O . O .
$$ . X X X X O .
$$ . . . . . O .
$$ . X O O , O .
$$ . X X X X O .
$$ . . . . . O .
$$ . X O O . O .
$$ . X X X X O .
$$ . . . . . O .
$$ . X O O , O .
$$ . X X X X O .
$$ . . . . . . .[/go]

$$B
$$ -------------
$$ . O X X . X .
$$ . O O O O X .
$$ . . . . . X .
$$ . O X X , X .
$$ . O O O O X .
$$ . . . . . X .
$$ . O X X . X .
$$ . O O O O X .
$$ . . . . . X .
$$ . O X X , X .
$$ . O O O O X .
$$ . . . . . . .

Click Here To Show Diagram Code

[go]$$B
$$ -------------
$$ . O X X . X .
$$ . O O O O X .
$$ . . . . . X .
$$ . O X X , X .
$$ . O O O O X .
$$ . . . . . X .
$$ . O X X . X .
$$ . O O O O X .
$$ . . . . . X .
$$ . O X X , X .
$$ . O O O O X .
$$ . . . . . . .[/go]

[Bill Spight]

As I guess you all know by now, I am still playing around with the Elf GoGoD commentaries, despite having better programs available now. But the Elf commentaries have a large number of rollouts, and the bulk of the work is already done. And as far as significant human mistakes are concerned, I doubt if it's opinion will differ much from today's top bots. OC, the winrate estimates will rarely agree.

Anyway, here is a game where I have worked out my best estimate, given the commentary, for winrate gains and losses to par (according to Elf). I have marked plays with more than a 12% estimated loss as Bad Moves. and I will mark those with more than an estimated 18% loss as Blunders. Since Elf has labeled a correct play in the endgame as a 6% loss, I have enlarged what I think of as Elf's margin of error. OC, this is a no komi game from the 19th century, so you have to take the commentary with a large grain of salt.



Enjoy!

This is an unfinished game. I don't know if a complete, annotated game would upload successfully.

[Bill Spight]

Memorial Day. Be well.

Another annotated game. Short, like the last. Same format.

BTW, the Elf commentaries call every choice by Elf a Tesuji. In case you were wondering.



In case you're wondering, Tamura is the future Honinbo Shusai Meijin.

Also in case you're wondering, White's kosumi, , got a tesuji tag because it got a better winrate estimate than Elf's top choice. OC, there's a lot of noise in the winrate estimates, even with a lot of rollouts.

[Bill Spight]

I wrote:

Here is a simple endgame corner position. Per convention, the outside White stones are alive. Territory scoring, counting territory in seki.

$$Bc Endgame corner
$$ -------------
$$ | . . . X O . .
$$ | O X X X O . .
$$ | . . X O O . .
$$ | X . X O . . .
$$ | O X X O . . .
$$ | O O O O . . .
$$ | . . . . . . .

Click Here To Show Diagram Code

[go]$$Bc Endgame corner
$$ -------------
$$ | . . . X O . .
$$ | O X X X O . .
$$ | . . X O O . .
$$ | X . X O . . .
$$ | O X X O . . .
$$ | O O O O . . .
$$ | . . . . . . .[/go]

Easy questions.

1) What is the usual territorial value of the corner?

2) How much does a gote or reverse sente gain?

jlt answered these questions. No point in hiding the answers now.

1) The usual territorial value of the corner is 3 pts, (for Black, by convention).

2) A gote or reverse sente gains 4 pts,

Next question:

3) When Black is komaster, what is the territorial value of the corner?

This question is ambiguous, as the territorial value depends upon whether Black makes the ko or not. My apologies for a poorly worded question.

jlt also answered this question, as well. it is 7 pts. if Black makes and wins the ko, and 3 pts. if Black does not make the ko.

Note, however, that if Black makes the ko, White gets points elsewhere in compensation for losing the ko, depending on when the ko is fought. That compensation is called the ko exchange.

That leaves three questions.

4) How much does each play in the ko gain, on average?

5) How much does Black gain by winning the ko versus the territorial value of the corner?

6) How should White play this corner?

4) is easy. 5) is ambiguous, as well. 6) is implied in the previous discussion between jlt and me, and the answer to 4).

4) How much does each play in the ko gain, on average?

This question is easy to answer for area scoring, as we just have to count the area covered by the corner. It is 16 pts. So winning or losing the ko makes a difference of 32 pts., and each move in the ko gains on average 32/3 = 10⅔ pts. To get the average gain under territory scoring which counts points in seki, we subtract 1 pt. and get 9⅔ pts.

5) How much does Black gain by winning the ko versus the territorial value of the corner?

Well, assuming correct play, Black will win the ko when she should and then the value of the corner is 7 pts., so she gains nothing by winning the ko. Not a good question, I am afraid, as it is a question of definition. My apologies.

6) How should White play this corner?

An important question, the answer to which may be counterintuitive.

In theory we assume that there are plays elsewhere about which we know nothing except how much the largest play or plays gain, which we call the ambient temperature. If we know more, the answer can get complicated. I know, because this is a question the likes of which I worked on for years. Berlekamp's komaster theory makes giving an approximate answer tractable. As we know more, the theory may be expanded to cover more complicated situations.

Since Black can win the ko Black does not need to waste a move to prevent the ko. Black can wait for White to atari the single stone, and then Black can make and win the ko. If White never plays that atari, then Black gets 7 pts. in the corner without trying. The question for White, then, is when to play the atari.

If White waits to play the atari until the ambient temperature, which is how much White can gain in the ko exchange, is 3 pts., then Black gets 7 pts. in the corner and White gets 3 pts., for a net result of 4 pts., on average, which is 1 pt. better than the usual average value of the corner. So White should play the atari, sooner, if possible.

How soon can White effectively make the atari?

1) Suppose that Black makes and wins the ko. Then White gains the ambient temperature, T, in exchange for 7 pts. in the corner. The net result is 7 - T, on average.

2) Suppose that Black ignores the atari and lets White kill the corner. The net result is 2T - 22. This is better for Black when T > 9⅔. So White can play the atari when T ≤ 9⅔. I.e., when the ambient temperature is low enough to fight the ko.

Edit: This is true so far as it goes, but as jlt pointed out, since by connecting Black returns to a position worth 3 pts., White can play the atari when the temperature is as high as 12½.

3) Suppose that Black simply connects without making seki. If T > 4, then play will continue elsewhere (as a rule) and the average value of the corner will be 3 pts. This is better for Black, on average, than making the ko, as 3 > 7 - T.

Putting all this together means that when Black is komaster, if White waits until T < 4 to play the atari, then Black will make and win the ko for a net result of 7 - T. However, when 9⅔ > T > 4, White will normally be able to play the atari with sente, and Black will connect for an average result of 3 pts. in the corner.

Typically such corner positions arise in the middle game, when the ambient temperature is high. So White will normally have many opportunities to play the atari with sente, and should do so, as a rule.

[jlt]

I still don't understand what happens if 9⅔ < T < 12½.

Since 2T-22 < 3, if ataris it is more interesting for Black to connect than to play elsewhere and let White kill the corner.

But how do you determine if is better at A17 (atari) or elsewhere?

[Bill Spight]

I still don't understand what happens if 9⅔ < T < 12½.

Since 2T-22 < 3, if ataris it is more interesting for Black to connect than to play elsewhere and let White kill the corner.

You're right. White can atari with sente up to T = 12½.

But how do you determine if is better at A17 (atari) or elsewhere?

In general, White will not take a loss by waiting unless the temperature drops below 4. But the closer the temperature gets to 4, the more likely that conditions will arise so that Black can afford to make the ko.

[Bill Spight]

Welcome news!

The book about my wife's great-great-grandmother, Henrietta Wood, has won the Pulitzer Prize in History. I got an email from the author, Caleb McDaniel, today.

See this note: viewtopic.php?p=248096#p248096

And here is a picture that Caleb took of Winona and me when he visited a few years ago. (Repost.)

[Bill Spight]

We don't need no stinking ladders

Here is a game of the early modern, i.e., post 1500, era, between Nakamura Doseki, Meijin, and Yasui Santetsu. Of some interest is White 102, which serves as a ladder maker. In its commentary, however, Elf prefers to make the atari for the non-ladder. OC, ladders are a weak spot for more than one top bot. You may wonder why I chose to show this variation. Then again, you may not.

[Bill Spight]

I have been thinking lately about how to advance as an SDK, and I remembered a player who was frustrated by being stuck for a long time at a certain level, who rose to the occasion, remade his game, and made solid progress.

So here's a shoutout to our friend, Fedya, an inspiration to us all.

[Kirby]

Congratulations about the book. And thanks for sharing your photo, again. I’ve seen that picture before, but it’s the only way I’ve ever been able to put a face to your name.

Regarding Fedya, what steps might have been involved to “remake his game”? I suppose it means to play better, or maybe with a different style. Anything else?

[Bill Spight]

Congratulations about the book. And thanks for sharing your photo, again. I’ve seen that picture before, but it’s the only way I’ve ever been able to put a face to your name.

Regarding Fedya, what steps might have been involved to “remake his game”? I suppose it means to play better, or maybe with a different style. Anything else?

I know that Fedya worked with Leela 11, and adopted a more aggressive style. His overall attitude improved, as well. A number of us recognized the transformation in a game he posted in April of last year. https://www.lifein19x19.com/viewtopic.php?f=4&t=16561

[Bill Spight]

Think like a Grand Robot.

Bots do make unusual plays. I just ran across one.

$$Bcm9 Up in the air, flying high
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . X . . . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . c . . . . . . . . . . . . . . . |
$$ | . . b . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , a . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . 7 . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . , 3 . . . . 6 . . . 1 . , O . . |
$$ | . . . X 2 4 . . . . . . . . O . . . . |
$$ | . . . 5 . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------

Click Here To Show Diagram Code

[go]$$Bcm9 Up in the air, flying high
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . X . . . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . c . . . . . . . . . . . . . . . |
$$ | . . b . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , a . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . 7 . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . , 3 . . . . 6 . . . 1 . , O . . |
$$ | . . . X 2 4 . . . . . . . . O . . . . |
$$ | . . . 5 . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

The four enclosure position is from a 19th century game, but could arise today. Black has fallen behind, because of the two tight enclosures.

In the game Black played at a, the traditional extension between facing enclosures, but the shoulder play is modern AI style. This diagram shows Elf's main variation for . The White response, - , is also the modern AI style. The jump. , is a new one on me, however. Elf gives it 17.9k rollouts. It is 1% better than b and c, which get 5.6k and 3.1k rollouts, respectively.

Is this jump on any other bot's radar? If not, how does it evaluate it? Thanks.

[lightvector]

Yes.

KataGo recent 40 blocks, large number of playouts, analysisWideRootNoise = 0.05, so as to force exploration and evaluation of a much wider range of moves.

kata40bwide005.png (1.15 MiB) Viewed 11941 times

And here's the raw policy, showing that the move also is fairly prominent in the bot's "instinct", suggesting that this "kind" of one point jump into the center is something that it would consider a plausible move in situations "like" this one, based on whatever generalizations the net is making from its training experience. Rather than something the bot itself considers unusual.

kata40brawpolicy.png (1.06 MiB) Viewed 11941 times

[ez4u]

If Black does not play locally next (e.g. extends at the top), does White have a specific local continuation to exploit Black's failure to play another move at the bottom? In other words, can the bot give us a hint why the local play is rated so high?

[Bill Spight]

Many thanks, lightvector. Verrrry interesting.

Elf, at any rate, does not particularly like either the New Fuseki or Cosmic Go. However, in many situations it does like jumps toward the center and other center tending moves. Interesting that in this specific case KataGo values this jump, as well.