BillSpightsElfPositionalJudgmentExercises/Game 7 ELF's Solution

Kitani Minoru, 8 dan (W) - Sakata Eio, 7 dan, Sept. 6, 1950  

GoGoD 1950-09-06a, 4½ pt. komi

White is ahead. Elf estimates White's winrate as 89½% with 46.6k playouts. But Black, Sakata, won by 3½ pts.

Elf's recommended continuation  

Elf like's Joaz's play for (40.8k playouts). :) After is a one space jump. You often see such a jump on the 4th line to bolster a group next to a corner. Elf probably stopped the variation here because the next play had fewer than 1.5k playouts. White's high winrate is not all that obvious.

To my eyes, though, Black's small life in the bottom right corner suggests that Black has made a mistake. Usually when you have a joseki where one player lives in the corner and makes a floating group, the corner is reasonably large, with 7 or more points of territory.

Dual purpose play, minor error  

is the textbook play for the formation on the bottom side, breaking symmetry with a dual purpose play, a combination of a 3 space pincer and a 5 space extension. (From this and other games, it is plain that Kitani, White, did not place much stock in those textbooks. ;)) The idea of making a dual purpose play is not a bad heuristic, but it is only a heuristic. Elf prefers the approach in the top left corner at a by 5½%. , by contrast, is a sizable mistake, according to Elf, losing 15% by comparison with the bot's favorite play at b. was, and still may be, joseki, BTW.

Elf's variation for White 8  

After the kikashi in the right side (25.6k playouts), encloses the top left corner.

Elf's variation for White 8, continued  

Then Black plays the press against the bottom left 3-4 stone.

Game continuation  

loses 12½% by comparison with a.

Elf's mainline variation for Black 13  

gets 119.1k playouts. is a new move in this joseki. threatens the two stones. After crosscuts and plays to take the cutting stone on the second line.

Elf's mainline variation for Black 13, continued  

saves the stones. Then threatens White's other four stones in the corner. makes life. Then (46.1k playouts) enlarges White's eyespace.

Elf's mainline variation for Black 13, continued  

Black blocks White on the bottom side. (17.5k playouts) carries the fight into the center.

Elf's mainline variation for Black 13, continued  

is tesuji. This is a long variation, thanks mainly to the large number of playouts for . It is long enough to show the value of Black's wall on the bottom side. :)

Back to the actual game. :)

Oh, no, I couldn't.  

If lost 12½%, returned the favor, and then some, losing 16½% by comparison with a.

Elf's mainline variation for  

After Black goes for outside influence, pressing against the C-04 stone and then returning to press down against the White group on the right side, and finally pushing down against the corner.

Black blunders  

With Sakata blundered, in Elf's eyes, losing 26½% by comparison with a.

Elf's mainline variation for  

Black sacrifices three stones for outside influence and sente.

Back to the game.

Error upon error  

Elf regards as a minor error, losing 5%. Then loses 16% more. :o Another blunder, I think, given the sequence of errors. Then runs out to the center, attacking Black's floating stones. Sakata was known for his ability at shinogi, but it may have played him false here. Small life in the corner was simply not good enough, in Elf's eyes.

Elf's choice for Black 19, kikashi before living  

Black plays and with sente before living with . These plays build central influence and support the stones. :)

There are no more errors losing 10% up to .