Surprising result (imo) in 3-4 approach variation

Fllecha · #1

Hi all,

I was analyzing with Leela the variation posted below (3-4 high approach, 2 space high pincer, variation from joseki) and the final result was for me a complete shock: white loses a big corner, gets in compensation some thickness BUT leela states that the game is at least even, at best slight advantage for white.

1) Main question: Can you kindly give some explanation of Leela's final evaluation (even game) while for me is an easy resignation for white?

2) Secondary question: Can you check the line where it is not sound? (I checked tactical issues with leela but one cannot be 100% sure.)

as usual thanks in advance

dfan · #2

Take anything I say here with a kyu-sized grain of salt, but here are my thoughts:

1) Imagine that an equal number of White prisoners and Black stones-inside-territory have been removed (this doesn't change the score). Of course you have to realize that the resulting weaknesses in Black's shape aren't real. The board then looks like this.

Click Here To Show Diagram Code: [go]$$c After removing stones $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . X X . . . . . . . . . . . | $$ | . . . . . X O . . . . . . . . . . . . | $$ | . . . , X O . O . , . . . . . X . . . | $$ | . . . X O O O . . . . . . . . . . . . | $$ | . X X O . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . O . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Does that still feel as bad?

2) In the real game, after White plays B12, Black is going to have to actually take the White stones off the board, as the D16 group has only one eye. Even the G18 group may have to spend time making its two eyes. So that's a bunch of moves Black is going to have to play with no purpose other than to take stones off the board while White is getting even more thickness on the outside.

I don't know if it's actually a good rule of thumb, but by default I am happy with almost any sacrifice that my opponent has to actually remove from the board.

(By the way, Crazy Stone evaluates the position after :w38:

@ B12 to be 53% for White.)

Gomoto · #3

1. White has a clear advantage

Think:
for every captured white stone black needed to place a move as well
and white build a nice outside wall during this time

nice sacrifice strategy

2. Tactical unsound moves?

I never play the tactical unsound high approach of D15 ;-)

(But your milage may vary).

Black B14 is a mistake and should be at H15.

I do not like white 1 (should be at 2) and a possible line for black is this: (black is better)

Click Here To Show Diagram Code: [go]$$W $$ ----------------- $$ | . . . . . . . . . $$ | . . 1 5 . 2 . . . $$ | 7 3 X O O X . . . $$ | . 6 4 X X O X 8 . $$ | . . . X O O O . . $$ | . . . . X . . . . $$ | . . . . . . . . . $$ | . . . O . . . . .[/go]

sorin · #4

Fllecha wrote:

Hi all,

I was analyzing with Leela the variation posted below (3-4 high approach, 2 space high pincer, variation from joseki) and the final result was for me a complete shock: white loses a big corner, gets in compensation some thickness BUT leela states that the game is at least even, at best slight advantage for white.

1) Main question: Can you kindly give some explanation of Leela's final evaluation (even game) while for me is an easy resignation for white?

I ran the final position with Leela, and it shows black as being ahead a little bit, having gained about 8% winrate, compared to the starting position.

So Leela agrees with you, white lost something in that exchange.
On the other hand, white built a lot of thickness on the outside, so the game is by no means over.

Fllecha · #5

Ok thanks sounds better now....

Last question: In the final position, left aside Leela's evaluation, with which side would you play?

Gomoto · #6

Sorry, I considered this position for white. (White ahead by a clear margin.)

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

Game is about even in your final position.

sorin · #7

Gomoto wrote:

Sorry, I considered this position for white. (White ahead by a clear margin.)

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

Game is about even in your final position.

I like black here, I agree with Leela's evaluation that black is ahead.
The game is still very much playable for both sides though.

Gomoto · #8

Be careful, in this position (not the OP's position) winrate for black is only 43% ;-)

Bill Spight · #9

dfan wrote:

Take anything I say here with a kyu-sized grain of salt, but here are my thoughts:

1) Imagine that an equal number of White prisoners and Black stones-inside-territory have been removed (this doesn't change the score). Of course you have to realize that the resulting weaknesses in Black's shape aren't real. The board then looks like this.

Click Here To Show Diagram Code: [go]$$c After removing stones $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . X X . . . . . . . . . . . | $$ | . . . . . X O . . . . . . . . . . . . | $$ | . . . , X O . O . , . . . . . X . . . | $$ | . . . X O O O . . . . . . . . . . . . | $$ | . X X O . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . O . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Does that still feel as bad?

For tewari purposes, you have to realize that the weaknesses in Black's position are real.

Quote:

2) In the real game, after White plays B12, Black is going to have to actually take the White stones off the board, as the D16 group has only one eye. Even the G18 group may have to spend time making its two eyes. So that's a bunch of moves Black is going to have to play with no purpose other than to take stones off the board while White is getting even more thickness on the outside.

Good point.

Quote:

I don't know if it's actually a good rule of thumb, but by default I am happy with almost any sacrifice that my opponent has to actually remove from the board.

Not a bad rule of thumb.

Bill Spight · **#10**

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

White has this sente. The average territory count remains the same. It would be interesting to see how Leela evaluates this position.

Click Here To Show Diagram Code: [go]$$Wc White sente, White gote follow-up $$ --------------------------------------- $$ | 2 O X X X . . . . . . . . . . . . . . | $$ | X O O O X X X X . . . . . . . . . . . | $$ | O O X O O X O . . . . . . . . . . . . | $$ | X X X X X O . O . , . . . . . X . . . | $$ | . W 3 X O O O . . . . . . . . . . . . | $$ | O B B O X . . . . . . . . . . . . . . | $$ | . O 1 O . . . . . . . . . . . . . . . | $$ | . O . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . X . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

captures the :bc:

stones and saves the :wc:

stone.

and

may be played now or later.

Click Here To Show Diagram Code: [go]$$Wc Tewari (i) $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . X X X . . . . . . . . . . . | $$ | . . . . . X O . . . . . . . . . . . . | $$ | X X X X X O . O . , . . . . . X . . . | $$ | . O O X O O . . . . . . . . . . . . . | $$ | @ . . O X . . . . . . . . . . . . . . | $$ | . O . O . . . . . . . . . . . . . . . | $$ | . W . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . X . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

10 stones of each player have been removed. White looks inefficient to me, considering the :wc:

stone. Also, if White plays the dame, :ws:

is inefficient.

Click Here To Show Diagram Code: [go]$$Bc White sente, Black gote follow-up $$ --------------------------------------- $$ | 3 O X X X . . . . . . . . . . . . . . | $$ | X O O O X X X X . . . . . . . . . . . | $$ | O O X O O X O . . . . . . . . . . . . | $$ | X X X X X O . O . , . . . . . X . . . | $$ | 5 W 1 X O O O . . . . . . . . . . . . | $$ | O B B O X . . . . . . . . . . . . . . | $$ | 4 O 2 O . . . . . . . . . . . . . . . | $$ | . O . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . X . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

saves the

stones and captures the :wc:

stone.

and

may be played later.

Click Here To Show Diagram Code: [go]$$Bc Tewari (ii) $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . X X X . . . . . . . . . . . | $$ | . . . . . X O . . . . . . . . . . . . | $$ | . X . X X O . O . , . . . . . X . . . | $$ | X . . X O O . . . . . . . . . . . . . | $$ | O X X O B . . . . . . . . . . . . . . | $$ | O O O O . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . X . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

In this diagram 11 stones of each player have been removed. Black may be able to make something with regard to the :bc:

stone.

Averaging the two tewari, Black looks more efficient.

Bill Spight · **#11**

I think I goofed with the tewari diagrams. White cannot afford to remove the White stone at G-15, as it gives too much play the Black stone at E-14.

Click Here To Show Diagram Code: [go]$$Wc Tewari (i) $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . X X X . . . . . . . . . . . | $$ | . . . . . X O . . . . . . . . . . . . | $$ | X X X X X O . O . , . . . . . X . . . | $$ | . O O X O O O . . . . . . . . . . . . | $$ | W . . O B . . . . . . . . . . . . . . | $$ | . O . O . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . X . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

OC, the

stone would be better one space toward the corner.

Click Here To Show Diagram Code: [go]$$Bc Tewari (ii) $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . X X X . . . . . . . . . . . | $$ | . . # . . X O . . . . . . . . . . . . | $$ | . X . X X O . O . , . . . . . X . . . | $$ | X . . X O O O . . . . . . . . . . . . | $$ | O X X O B . . . . . . . . . . . . . . | $$ | O O O O . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . X . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

In this diagram the :bs:

stone is plainly superfluous.

I think that the key to evaluating both diagrams is the assessment of the :bc:

stone.

sorin · **#12**

Gomoto wrote:

Be careful, in this position (not the OP's position) winrate for black is only 43% ;-)

Oh, I see - sorry! I thought it is the same position.
In your position, it is as if white has pushed one more time on the 3rd line, and black replied on the 2nd, I see - that must be a gain for white compared to OP's position.

Also, to the tewari analysis dfan posted: one cannot just remove a cutting stone from the "outside" of the position; for tewari purposes, only dead/inert inside stones are usually cancelling each other out and can be removed.

dfan · **#13**

sorin wrote:

Also, to the tewari analysis dfan posted: one cannot just remove a cutting stone from the "outside" of the position; for tewari purposes, only dead/inert inside stones are usually cancelling each other out and can be removed.

Thanks (and also to Bill Spight). I didn't know there were rules for this sort of thing (I'm only familiar with tewari in the sense of reordering moves), so it's just a heuristic I use to get a better sense of how many points a capture is worth, since often it looks worse than it is.

John Fairbairn · **#14**

I found this thread fascinating but alarming as to what it says about amateur go.

As an amateur I have no definitive ideas either, but trying to apply some pro insights I get the same result as Leela - slightly favouring White.

First the tewari as done here seems dubious to me. Even Bill's. I'm at a natural disadvantage here as the position needs more fingers than I've got, but in tewari (ii) I don't see how you can justify ending up with a position where locally both sides have the same number of stones but Black has one more stone on the board as a whole, whereas in the game they have played an equal number of stones overall.

Next, applying the pro rule of thickness being worth (n * n+1)/2 with n being the length of the wall (but not usually counting stones on the edges - the rule of each stone in a wall being worth 3 points is an approximation of this for the commonest lengths of wall). On that basis I assume a wall of 8 gives White about 36 points, with an averaged few extra points for the late boundary plays on the upper left side. Black has just over 20. Since Black as an extra stone elsewhere on the board which can be counted as 15 points, White has significant advantage. It's true that the cutting black stone at E14 will possibly have some influence (e.g. Black can maybe make a good play around the point), but there is a case for saying White's wall could be counted as 9 (giving 45 points), so I'd assume these two things balance out.

I'm also very dubious about White D6. Thickness is not thickness unless it functions as thickness. That means attacking. This D6 is a pure gote defence move and smacks of overconcentration and of thinking only of territory. You make territory in the region of thickness by surrounding it dynamically, i.e. by attacking and keeping sente. A positive attitude such as F5 or a pincer seems called for here.

Gomoto · **#15**

I refuse to enter the B15 E18 exchange :twisted:

Zen 7 white D6 (best move according to Zen) winrate for black 44%

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

Zen 7 white F5 winrate for black 46%

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

Zen 7 white J4 winrate for black 46%

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

Zen 7 white H3 winrate for black 48%

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

Gomoto · **#16**

(Sorry for the thread hijacking)

Pincers (are) were overrated in Go theory.

My view since the advent of neural nets is:
You do not need to know why a move is good, you just need to know the good move.
The request to explain a move is therefore superfluous.
Just know your moves, if you want to play strong go :twisted:

sorin · **#17**

John Fairbairn wrote:

I'm also very dubious about White D6. Thickness is not thickness unless it functions as thickness. That means attacking. This D6 is a pure gote defence move and smacks of overconcentration and of thinking only of territory. You make territory in the region of thickness by surrounding it dynamically, i.e. by attacking and keeping sente. A positive attitude such as F5 or a pincer seems called for here.

I believe playing on the left side (around D6) is good in this case for white.
White's thickness is too far away to use directly, so he needs to build a moyo first, lure black in, so he can attack and use the thickness.

If white plays pincer on the lower side instead, when black approaches on the left side (around C6) he will settle in there easily (discarding the stone on the lower side) and white's thickness above goes to waste.
Alternatively, black can reply to white's pincer by simply entering 3x3 and again settles quickly if white follows the common-sense way of blocking at D3, etc.

Bill Spight · **#18**

John Fairbairn wrote:

First the tewari as done here seems dubious to me. Even Bill's. I'm at a natural disadvantage here as the position needs more fingers than I've got, but in tewari (ii) I don't see how you can justify ending up with a position where locally both sides have the same number of stones but Black has one more stone on the board as a whole, whereas in the game they have played an equal number of stones overall.

Yes, there are questions with my tewari.

I have actually thought a bit more about it. I was trying an experiment of averaging tewari after each side played a small gote. I think that that makes sense, but it adds difficulty. As for tewari (ii), Black has made an extra move that gains only 3.5 pts., so it is not surprising that the position is inefficient for Black during the opening. How do you average tewari (i) and tewari (ii)? Not easy.

Also, I am doing tewari at a different position than some are evaluating.

Click Here To Show Diagram Code: [go]$$Wc Position to tewari $$ --------------------------------------- $$ | . O . X . . . . . . . . . . . . . . . | $$ | X O O O B X X X . . . . . . . . . . . | $$ | O O X O O X O . . . . . . . . . . . . | $$ | X X X X X O C O . , . . . . . X . . . | $$ | . W . X O O O . . . . . . . . . . . . | $$ | . X X O X . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . O . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . W . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . B . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Not everybody else is including the marked stones. And we should remember that Black has played a stone at :ec:

.

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

We humans can simplify the position to evaluate by playing White's sente. The top left side is still unsettled, in the sense that there is a small gote left. However, we can simplify further.

Click Here To Show Diagram Code: [go]$$Wc Position for tewari $$ --------------------------------------- $$ | B O X X X . . . . . . . . . . . . . . | $$ | X O O O X X X X . . . . . . . . . . . | $$ | O O X O O X O . . . . . . . . . . . . | $$ | X X X X X O C O . , . . . . . X . . . | $$ | . O . X O O O . . . . . . . . . . . . | $$ | O X X O X . . . . . . . . . . . . . . | $$ | . O W O . . . . . . . . . . . . . . . | $$ | . O . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . X . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

In the yose, regardless of who plays first in the top left, Black will play :bc:

and capture the White stones and White will play :wc:

. So this is the simplified position to evaluate.

In this position there is still a 3.5 pt. gote in the corner, but it is contained. Locally it is worth 1.5 pts. for White. Black to play can make 2 pts.; White to play can make 5 pts.

Click Here To Show Diagram Code: [go]$$Wc Tewari $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . X X X . . . . . . . . . . . | $$ | . . . . . X O . . . . . . . . . . . . | $$ | X X X X X O . O . , . . . . . X . . . | $$ | . O . X O O O . . . . . . . . . . . . | $$ | O X X O B . . . . . . . . . . . . . . | $$ | . O O O . . . . . . . . . . . . . . . | $$ | . W . @ . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . X . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Black has captured 8 White stones in the corner and White has captured 1 Black stone. We balance the captures by removing 7 Black stones from the corner. I think that this tewari clearly favors Black in the top left corner. The :bc:

stone has aji, but the :wc:

stone is plainly badly placed. Those two stones are not equivalent, but if we treat them as equivalent and remove them, the :ws:

stone is badly placed. Definitely good for Black.

Bill Spight · **#19**

Gomoto wrote:

(Sorry for the thread hijacking)

I don't think it is hijacking.

Quote:

Pincers (are) were overrated in Go theory.

Apparently a lesson from AlphaGo Master. However, AlphaGo Zero pincers more often than Master. Probably less than humans do now, though. My impression is that Zen pincers even more often. Zen obviously favors the one space reply over the other moves, but only the one space pincer is outside the margin of error, IMO.

Quote:

My view since the advent of neural nets is:
You do not need to know why a move is good, you just need to know the good move.
The request to explain a move is therefore superfluous.
Just know your moves, if you want to play strong go :twisted:

The idiot savant theory of go.

Bill Spight · **#20**

John Fairbairn wrote:

Next, applying the pro rule of thickness being worth (n * n+1)/2 with n being the length of the wall (but not usually counting stones on the edges - the rule of each stone in a wall being worth 3 points is an approximation of this for the commonest lengths of wall).

Prone to overestimation, IMO — and I like thickness! I think that a 3.5 pt. approximation is better, as a rule.

Quote:

On that basis I assume a wall of 8 gives White about 36 points, with an averaged few extra points for the late boundary plays on the upper left side. Black has just over 20. Since Black as an extra stone elsewhere on the board which can be counted as 15 points, White has significant advantage.

Huh? 20 + 15 = 35, so White by that reckoning has a slight advantage.

FWIW, my influence function pretty much agrees. It thinks that White is around 7 pts. ahead. It is biased towards the outside, so if we take that into account, White has a slight advantage.

Quote:

I'm also very dubious about White D6. Thickness is not thickness unless it functions as thickness. That means attacking. This D6 is a pure gote defence move and smacks of overconcentration and of thinking only of territory. You make territory in the region of thickness by surrounding it dynamically, i.e. by attacking and keeping sente. A positive attitude such as F5 or a pincer seems called for here.

I also like F-05.

But D-06 makes a moyo, not territory. Strong go players of yore made similar moyo. One advantage of D-06 is that it reduces uncertainty. Since Zen thinks that White is ahead, that is a plus.

Edit: OC, Zen is assuming a 7.5 komi to get that advantage for White.

Surprising result (imo) in 3-4 approach variation

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