How is your positional judgement? Game 18

Bill Spight · #1

As always, assume area scoring and 7½ pt. komi.

After :b31:

Elf estimates one player's winrate as 93½% with 27.7k playouts. Which player is it?

Click Here To Show Diagram Code: [go]$$Bcm31 White to play $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . O O X X . . . . . X . . O . X . . . | $$ | . . . O . X . . X , . . . . . , X . . | $$ | . . O . . . . . . . O . . . . . . . . | $$ | . . . . . . . . . . . . . O . . . . . | $$ | . . . . . . . . . . . . . . X X . . . | $$ | . . . . . . . . . . . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O , . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . O . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . . , X O . . . , . . . . . , . . . | $$ | . . . X O O . . . O . . . . . O . . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Enjoy!

jlt · #2

Uberdude · #3

Bki · #4

bernds · #5

Tryss · #6

TelegraphGo · #7

Knotwilg · #8

No LZ

LZ

Bill Spight · #9

Game 18

Iwamoto Kaoru (W) vs. Fujisawa Kuransuke, Honibo League, September, 1950 (GoGoD 1950-98-22a)

The komi for the Honinbo Tournament was 4½ pts. at the time.

After :b31:

Elf estimates Black's winrate as 93½% (27.7k playouts). Black won by 3½ pts.

Click Here To Show Diagram Code: [go]$$Bcm29 Black is ahead. $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . O O X X . . . . . X a . O . X . . . | $$ | . . . O . X . . X , . . . . . , X . . | $$ | . . O . . . . . . . O . . . . . . . . | $$ | . . . . . . . . . . . . . O . . . . . | $$ | . . . . . . . . . . . . . . 3 X . . . | $$ | . . . . . . . . . . . . . . . 2 . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O , . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . b . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . O . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . . , X O . . . , . . . . . , . . . | $$ | . . . X O O . . . O . . . . . O . . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Elf thinks that :w30:

is a mistake, losing 9% to the attachment at a. For :w32:

Elf recommends the attachment at b, but the play from there is complicated, and Elf regards a, which Iwamoto played in the game, as only ½% worse, so I shall show Elf's continuation from there.

Click Here To Show Diagram Code: [go]$$Bcm33 Elf's continuation from , marked $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . 1 5 . . . . . . | $$ | . O O X X . . . . . X W . O . X . . . | $$ | . . . O . X . . X , . 2 . . . , X . . | $$ | . . O . . . . 7 6 . O . . . . . . . . | $$ | . . . 3 . . . . . . . . . O . . . . . | $$ | . 4 . . . . . . . . . . . . X X . . . | $$ | . . . . . . . . . . . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O , . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . O . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . . , X O . . . , . . . . . , . . . | $$ | . . . X O O . . . O . . . . . O . . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

is the underneath hane, to which White stands, solidifying his group. :b35:

takes kikashi in the top left and then :b37:

prevents White from making eye shape on the second line. The variation stops here, probably because the playouts for future play dropped below 1500.

Earlier in the game

Click Here To Show Diagram Code: [go]$$Bc Unexpected error $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . 3 . . . . . . . . . 6 . . . . . | $$ | . . . , . . . . . , . . . . . , 1 . . | $$ | . . 4 . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . 5 . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . a . . . . . . . . . . . . 2 . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

is an error that loses 11½% to par, according to Elf. It is not that the ogeima approach is so bad, per se, it is that the 3-3 invasion at a in the bottom left corner is so good. The value of these early 3-3 invasions was not suspected before the advent of AI.

Elf's mainline variation for :w6:

Click Here To Show Diagram Code: [go]$$Wcm6 3-3 invasion $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , X . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . 0 . . . . . . . . . . . . . . . | $$ | . . 9 8 . . . . . . . . . . . . . . . | $$ | . . 7 6 . . . . . . . . . . . . . . . | $$ | . . 5 X . . . . . . . . . . . . . . . | $$ | . . . 3 4 . . . . , . . . . . , . . . | $$ | . . 1 . 2 . . . . . . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

White invades the bottom left corner and claims territory while Black makes a sizable wall.

Click Here To Show Diagram Code: [go]$$Wcm16 3-3 invasion, continued $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . 4 , . 6 . . . , . . . 2 . , X . . | $$ | . . O 5 . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . 7 . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . O X . . . . . . . . . . . . . . . | $$ | . . O X . . . . . . . . . . . . 1 . . | $$ | . . O X . . . . . . . . . . . . . . . | $$ | . . . O X . . . . , . . . . . , . . . | $$ | . . O . X . . . . . 3 . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

encloses the bottom right corner. Then :b17:

makes a two space high enclosure in the top right, which was not popular before the AI era. :w18:

extends on the bottom side, reducing Black's influence there. The bots have devalued the sides, but each corner has at least two stones in it. Next, Black plays a kick joseki in the top left corner, another joseki that was not popular before the bot era. Then, :w22:

jumps on the third line on the left side, making some territory and forming a 5 space extension from the two White stones in the corner. Dogma at the time was that such extensions are too far. The bots don't care.

Later in the game

Click Here To Show Diagram Code: [go]$$Bcm19 blunders $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . 1 . . . . . . . . . . . . . . . . | $$ | . 0 O X 3 . . . . . X . . O . X . . . | $$ | . . . 2 . X . . X , . . . . . , X . . | $$ | . . O . . . . . . . O . . . . . . . . | $$ | . . . . . . . . . . . . . O . . . . . | $$ | . . . . . . . . . . . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . 9 . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . O . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . . , 5 8 . . . , . . . . . , . . . | $$ | . . . X 4 6 . . . O . . . . . O . . . | $$ | . . . 7 . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Elf says that the natural looking extension, :b21:

, loses 19½% to par. :w22:

switches to the third line attachment against the Black enclosure in the bottom left corner. :b27:

secures territory in the bottom left co[rner. Then :w28:

descends in the top leftcorner. Instead of :w26:

Elf prefers 27 by 5½%.

Elf's recommended variation for :b21:

Click Here To Show Diagram Code: [go]$$Bcm21 Atari first $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . 1 O X 7 . . . . . X . . O . X . . . | $$ | . . 6 O . X . . X , . . . . . , X . . | $$ | . . O . . . . . . . O . . . . . . . . | $$ | . . . . . . . . . . . . . O . . . . . | $$ | . . . . . . . . . . . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . 8 . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . O . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . . , 3 . . . . , . . . . . , . . . | $$ | . . . X 2 4 . . . O . . . . . O . . . | $$ | . . . 5 . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

connects and :b27:

extends. White could have played this exchange earlier. Comparing the two diagrams, it seems like the main point playing the atari at :b21:

is this exchange.

Ironically, Elf regards the descent at :w28:

as a blunder, losing 20%.

White has a superior play in the next diagram.

Click Here To Show Diagram Code: [go]$$Wcm28 Third line attachment $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . O X X . . . . . X . . O . X . . . | $$ | . . . O . X . . X , . . . . . , X . . | $$ | . . O . . . . . . . O . . . . . . . . | $$ | . . . . . . . . . . . . . O . . . . . | $$ | . . . . . . . . . . . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O , . . . . . , . . . . . , . . . | $$ | . 9 . 0 . . . . . . . . . . . . . . . | $$ | . . 1 2 . . . . . . . . . . . . . . . | $$ | . 3 X a . . . . . . . . . . . . . . . | $$ | . 7 4 . . . . . . . . . . . . . O . . | $$ | . 8 . X . . . . . . . . . . . . . . . | $$ | . . 5 6 X O . . . , . . . . . , . . . | $$ | . . . X O O . . . O . . . . . O . . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

= a

plays a second third line attachment. :b29:

plays the top hane. (If :b29:

is at a,

is the same.) After :w30:

pulls back. The peep, :w32:

, the crawl, :w34:

, and the cut, :w38:

, leave White some aji in the corner.

So Black and White traded blunders. Other than that, :w6:

missed the 3-3 invasion, which was probably heresy at the time. Other than that, Black took a strong lead because of an accumulation of relatively small errors by White.

Edited typos.

Uberdude · **#10**

Bill Spight wrote:

Click Here To Show Diagram Code: [go]$$Bcm19 blunders $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . 1 . . . . . . . . . . . . . . . . | $$ | . 0 O X 3 . . . . . X . . O . X . . . | $$ | . . . 2 . X . . X , . . . . . , X . . | $$ | . . O . . . . . . . O . . . . . . . . | $$ | . . . . . . . . . . . . . O . . . . . | $$ | . . . . . . . . . . . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . 9 . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . O . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . . , 5 8 . . . , . . . . . , . . . | $$ | . . . X 4 6 . . . O . . . . . O . . . | $$ | . . . 7 . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Elf says that the natural looking extension, :b21:

, loses 19½% to par. :w22:

switches to the third line attachment against the Black enclosure in the bottom left corner. :b27:

secures territory in the bottom left co[rner. Then :w28:

descends in the top right corner. Instead of :w28:

Elf prefers 29 by 5½%.

Elf's recommended variation for :b21:

Click Here To Show Diagram Code: [go]$$Bcm21 Atari first $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . 1 O X 7 . . . . . X . . O . X . . . | $$ | . . 6 O . X . . X , . . . . . , X . . | $$ | . . O . . . . . . . O . . . . . . . . | $$ | . . . . . . . . . . . . . O . . . . . | $$ | . . . . . . . . . . . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . 8 . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . O . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . . , 3 . . . . , . . . . . , . . . | $$ | . . . X 2 4 . . . O . . . . . O . . . | $$ | . . . 5 . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

connects and :b27:

extends. White could have played this exchange earlier. Comparing the two diagrams, it seems like the main point playing the atari at :b21:

is this exchange.

Ironically, Elf regards the descent at :w28:

as a blunder, losing 20%.

I remember reading the opinion of Go Seigen (maybe in John's books) that against this bulge shape in the corner of :w20:

black should essentially always atari. If we knew White we going to make the heavy empty triangle connection then I'm sure everyone would. But we expect White to counter atari and breaks through the side. That's a joseki too, but that Elf thinks the dumb connection (which teachers would tell you off for) is better than that trade shows we have misevaluated it. I think us humans, even top pros, tend to be too attached to the territory we are building on the top side and lack the flexibility to willingly give that up when White breaks through (but the counter argument is that it's consistent and avoids those stones becoming misplaced). But when that happens black gets good corner profit and the White group isn't thickness but still weak and attackable. Of course Go Seigen was known for his flexibility so was more willing to go for the complicated trade line spurrrd in by the desire to play the strongest local move.

Click Here To Show Diagram Code: [go]$$Bcm19 fighting spirit trade $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . 1 6 . . . . . . . . . . . . . . . | $$ | . 3 7 X 4 . . . . . X . . O . X . . . | $$ | . . 5 2 8 X . . X , . . . . . , X . . | $$ | . . O 9 . . . . . . O . . . . . . . . | $$ | . . . . . . . . . . . . . O . . . . . | $$ | . . . . . . . . . . . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . O . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . X . . . . . O . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

P.S if White wants to get the bulge shape without giving black a good chance to resist then the 2nd line crosscut at d18 is a good tesuji for situations like this with black strong on the top side so you are happy to overconcentrate.

dhu163 · **#11**

How is your positional judgement? Game 18

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