How is your positional judgement?

Bill Spight · Post by **Bill Spight** » Sat Nov 09, 2019 8:08 am

My discussion of Elf's commentary on Game 16

O Rissei, 9dan (W) - Kato Masao, 9 dan, 1998-02-19a

After

Elf estimates White's winrate as 89% with 59.6k playouts. White, O Rissei, won by 1½ pts.

Click Here To Show Diagram Code: [go]$$Bcm23 White is ahead $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . X . . . . . . . . X . . . . . | $$ | . . X , . O . . . , . . . . . , X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . O . . . . . . | $$ | . . . . . . . . . 2 a X O . . . . . . | $$ | . . . O . . . . 4 1 O O X O O , O O . | $$ | . . . . . . . . . 5 3 . X X . . X . . | $$ | . . . . . . . . . . X . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Black's bad shape, the empty triangle on the bottom side, is a clue. However, Kato, who was no slouch, had just played to create it. Perhaps he thought that

would connect at a. If so, he was right, O Rissei did play

at a. Elf disagrees. It regards

as a blunder, costing 19%.

Click Here To Show Diagram Code: [go]$$Wcm28 Elf's mainline variation for :w28: $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . X 3 . . . . . 9 . X . . . . . | $$ | . . X , 4 O . . . , . . . . . , X . . | $$ | . . . . . 5 . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . 8 . . . . . . . . . . . . 1 . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . 2 . . . . . . . . . O . . . . . . | $$ | . . . . . . . . 6 O . X O . . . . . . | $$ | . 7 . O . . . . O X O O X O O , O O . | $$ | . . . . . . . . . X X . X X . . X . . | $$ | . . . . . . . . . . X . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

is big, enlarging White's right side moyo. Instead of replying to

White turns to the top side, making a three stone wall. Next, the cut at

is big.

is interesting, avoiding an extension towards the right, which would not have a good follow-up to its right.

approaches the top right enclosure. It may also be considered as an extension from the three stone White wall. OC, the bots do not care about the human rules for such extensions.

Earlier in the game

Click Here To Show Diagram Code: [go]$$Wcm14 :w14: loses 13% versus [b]a[/b] $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . X . . . . . . . . X . . . . . | $$ | . . X , . O . . . , . . . . . , X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , 1 . a O O , O . . | $$ | . . . . . . . . . . . . X X . . . . . | $$ | . . . . . . . . . . . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Elf regards

as a mistake, preferring the simple and strong push at a.

Click Here To Show Diagram Code: [go]$$Wcm14 Elf's mainline variation for :w14: $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . X 3 . . . . . . . X . . . . . | $$ | . . X , 4 O . . . , . . . . . , X . . | $$ | . . . . . 5 . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . 0 . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . 6 8 . . . . . . . . . . . . . . . | $$ | . . 7 . . . . . . . . . . . . . . . . | $$ | . . . O . 9 . . . , . . 1 O O , O . . | $$ | . . . . . . . . . . . 2 X X . . . . . | $$ | . . . . . . . . . . . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

After

White turns to the top left corner, making the three stone wall. White replies to

with a kick and jump. The fact that

is high suggests that White is looking to attack

and

.

Click Here To Show Diagram Code: [go]$$Wcm24 Elf's mainline variation for :w14:, continued $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . X O . . . . . . 2 X . . . . . | $$ | . . X , X O . . . , 3 . 1 . . , X . . | $$ | . . . . . O . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . 5 . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . B B . . . . . . . . . . . . . . . | $$ | . 7 O . . . . . . . . . . . . . . . . | $$ | . . . O . O . . . , . . O O O , O . . | $$ | . . 6 . . . . . . . . X X X . . . . . | $$ | . . . . 4 . . . . . . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

plays the Go Seigen/AI shoulder blow against the top right enclosure.

takes advantage of White's high posture in the bottom left corner to play a submarine attack.

and

play a counterattack against the

stones.

The actual game continues.

Click Here To Show Diagram Code: [go]$$Wcm20 Mutual misunderstanding $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . X . . . . . . . . X . . . . . | $$ | . . X , . O . . . , . . . . . , X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X O . . . . . . | $$ | . . . O . . . . . , O 1 X O O , O O . | $$ | . . . . . . . . . . . . X X . . X . . | $$ | . . . . . . . . . . 2 . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Elf estimates that

loses 15½% to par.

returns the favor, losing 17½%. This kind of exchange of nearly equal mistakes suggests a shared misunderstanding of the position.

Click Here To Show Diagram Code: [go]$$Wcm20 Elf's mainline variation for :w20: $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . X . . . . . . . . X . . . . . | $$ | . . X , . O . . . , . . . . . , X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . 1 . . . . . . | $$ | . . . . . . . . . 4 2 B O . . . . . . | $$ | . . . O . . . . 3 5 W 6 X O O , O O . | $$ | . . . . . 7 . . . . . . X X . . X . . | $$ | . . . . . . . . . . . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

stands instead of cutting off the

stone. OC, cutting off the

stone shows fighting spirit, and is consistent with

(

). Not to cut off the

stone suggests that

was a mistake. Elf would agree.

and

push along the fifth line, forming a center facing wall, before connecting with

.

jumps along the fourth line and then:w24: connects. In effect, Black has forced White to "crawl" along the fourth line. According to traditional go wisdom, that is ill advised. However, the bots ofter prefer to make center facing walls on the fifth line in exchange for the opponent's edge facing walls on the fourth line. The bots have a lot to teach us about center oriented play.

Click Here To Show Diagram Code: [go]$$Bcm27 Elf's mainline variation for :w20:, II $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . X . . . . . . . . X . . . . . | $$ | . . X , . O . . . , . . . . . 7 X . . | $$ | . . . . . . . . . . . . . . 2 . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . 1 . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . O . 4 . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . 5 . 3 . . . | $$ | . . . . . . . . . . . . . . . . 6 . . | $$ | . . . . . . . . . . . . O . . . . . . | $$ | . . . . . . . . . X X X O . . . . . . | $$ | . . . O . . . . O O O X X O O , O O . | $$ | . . . . . O . . . . . . X X . . X . . | $$ | . . . . . . . . . . . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

approaches White's small moyo on the right side. The resulting sequence illustrates Elf's light, flexible play.

on the 5-5 threatens to cut off

or to invade the Black enclosure.

invades the White moyo. OC, Black's fifth line wall offers support for this invasion.

separates

and

, attacking both.

jumps out into the center and then

defends the White territory. Finally,

defends the Black position in the top right.

Click Here To Show Diagram Code: [go]$$Wcm34 Elf's mainline variation for :w20:, III $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . X 1 . . . . . . . X . . . . . | $$ | . . X , 2 O . . . 4 . . . . . X X . . | $$ | . . . . 8 3 . . . . . . . . O . . . . | $$ | . . . 7 9 0 . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . 5 X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . O . O . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . X . X . . . | $$ | . . . . . . . . . . . 6 . . . . O . . | $$ | . . . . . . . . . . . . O . . . . . . | $$ | . . . . . . . . . X X X O . . . . . . | $$ | . . . O . . . . O O O X X O O , O O . | $$ | . . . . . O . . . . . . X X . . X . . | $$ | . . . . . . . . . . . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

builds the three stones wall on the top side. Then

attacks it while extending on the side.

bolsters White's position in the top right and then

defends his invasion.

takes the double keima, then

and

push and cut, and the opening fight continues.

Next we look at Elf's variation for

in the actual game

Click Here To Show Diagram Code: [go]$$Bcm21 Elf's mainline variation for :b21: $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . X . . . . . . . . X . . . . . | $$ | . . X , . O . . . , . . . . . , X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . 6 5 7 . . . . . | $$ | . . . . . . . . . 9 . 1 2 . 8 . . . . | $$ | . . . . . . . . . 3 . X O . . . . . . | $$ | . . . O . . . . . 4 W W X O O , O O . | $$ | . . . . . . . . . . . . X X . . X . . | $$ | . . . . . . . . . . . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

The stand,

, looks right and left, taking aim at the

stones and at White's weakness in the bottom right.

threatens the one and then

threatens the other.

is a strong riposte, cutting Black in two.

Click Here To Show Diagram Code: [go]$$Wcm30 Elf's mainline variation for :b21:, continued $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . X . . . . . . . . X . . . . . | $$ | . . X , . O . . . , . . . . . , X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . O X X . . . . . | $$ | . . . . . . . . . X . X O . O . . . . | $$ | . . . . . . . . . X . X O . . . . . . | $$ | . . . O . . . . . O O O X O O 3 O O . | $$ | . . . . . . . . . . . 5 X X 6 . X 2 . | $$ | . . . . . . . . . . . 1 4 . a X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

turns to attacking the Black corner.

shores up a White weakness and threatens to play at a.

and

secure the Black group.

Back to the game.

Click Here To Show Diagram Code: [go]$$Wcm22 Overplay $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . X . . . . . . . . X . . . . . | $$ | . . X , . O . . . , . . . . . , X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . 1 . . . . . . | $$ | . . . . . . . . . . . X O . . . . . . | $$ | . . . O . . . . . 2 O O X O O , O O . | $$ | . . . . . . . . . . . . X X . . X . . | $$ | . . . . . . . . . . X . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

may be a tesuji. but Elf indicates that it is an overplay, losing 13½% to par.

Click Here To Show Diagram Code: [go]$$Bcm23 Elf's mainline variation for :b23: $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . X 6 . . . . . 0 . X . . . . . | $$ | . . X , 7 O . . . , . . . . . , X . . | $$ | . . . . . 8 . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . .9. . . . . . . . . . . . 2 . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . 5 . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . 3 . . . . . . . . . O . . . . . . | $$ | . 4 . . . . . . . . . B O . . . . . . | $$ | . . . O . . . . . . O O X O O , O O . | $$ | . . . . . . . . . 1 . . X X . . X . . | $$ | . . . . . . . . . . X . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

is a solid play, but gote. The checking extension,

, is big.

approaches the bottom left corner. White replies with the footsweep,

, as

hinders White's development on the bottom side.

is an interesting play, threatening to save

, as well as to invade the right side. White now turns to develop the top side, as we have seen above.

Back to the game.

Click Here To Show Diagram Code: [go]$$Wcm24 Blunder $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . X . . . . . . . . X . . . . . | $$ | . . X , . O . . . , . . . . . , X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . O . . . . . . | $$ | . . . . . . . . . 1 . X O . . . . . . | $$ | . . . O . . . . 3 X W W X O O , O O . | $$ | . . . . . . . . . 4 2 . X X . . X . . | $$ | . . . . . . . . . . X . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

threatens the

stones, but it is a blunder. According to Elf it loses 30%.

Click Here To Show Diagram Code: [go]$$Bcm25 Elf's mainline variation for :b25: $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . X 8 . . . . . . . X . . . . . | $$ | . . X , 9 O . . . , . . . . . , X . . | $$ | . . . . . 0 . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . 2 . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . 3 . B . . . . . . . O . . . . . . | $$ | . . . . . . . . 4 O . X O . . . . . . | $$ | . 5 . O . . . 6 1 X O O X O O , O O . | $$ | . . . . . . . . . a . . X X . . X . . | $$ | . . . . . . . . 7 . X . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

=

is typical when Black does not need to play at a. In this position, White does not answer

in the corner, but pushes in the center. After the now rare slide,

, White plays the hane,

, and

protects, forming a table shape. Next, White forms a three stones wall on the top side. Then

jumps into the center.

Attack and Kill Kato blundered on the bottom side with a strong local attack, accepting bad shape in the process. He probably assumed that O Rissei would save his two stones, which he did, making his own blunder. We warn beginners against overvaluing a few stones. It just goes to show that even 9 dans can sometimes make kyu level plays.

xela · Post by **xela** » Sat Nov 09, 2019 3:30 pm

Uberdude wrote:Elfv2 (which I think is what was used for the historical analysis Bill is using, but not sure) is way more extreme than that, a pass for the first move gives white >98.5%.

Surely a pass on the first move means that white can also pass and win by komi? So actually the winrate should be 100%, but 98.5% is within the margin of error :-) Do you get the same result if you make an SGF file that has an empty board and "white to play" (so there isn't a previous black pass)?

Knotwilg · Post by **Knotwilg** » Mon Nov 25, 2019 4:55 am

I've started https://senseis.xmp.net/?BillSpightsElf ... tExercises

If someone wants to help out doing the C&P work, be my fellow!

Bill Spight · Post by **Bill Spight** » Sun Dec 01, 2019 5:50 pm

I posted Game 25 today.

During the holiday season I plan to catch up with the comments. I may post another game, but maybe not.

Enjoy your holidays.

Or, as we say in the US, Happy War on Christmas!

Life In 19x19

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