BillSpightsElfPositionalJudgmentExercises/Game 17 ELf's Solution

White is ahead  

Elf's mainline continuation

Elf's mainline  

Kato played the two step hane. The rest is Elf's variation. plays a hanging connection to secure the Black group. Then takes kikashi against the bottom right corner, then makes a trumpet connection. Black takes kikashi against that and then invades the top left corner.

Elf's mainline, continued  

eliminates the aji of the stone. prevents the extension on the top side with sente, then secures the corner and creates an open skirt for White. makes a three space high extension from White's wall. No point in a low extension because of the open skirt.

Black has taken all four corners, but Elf judges White's outside strength to be commanding.

Earlier in the game.

Probe  

Through was a popular fuseki, with the probe, , regarded as an improvement. However, Elf thinks that is a minor error, losing 7% to par. Elf prefers Wa - Bb, Wc. The bots do like the solid connection at a. :)

Three in a row  

Elf thinks Black made three mistakes in a row. lost 7% to par, lost 11½%, and lost 15½%. All that to capture one stone! After Elf gives Black a 20% chance to win the game (60.1k playouts).

Elf's variation for  

extends on the second line, avoiding White's kikashi there. and play kikashi against the corner, then returns to the bottom right corner with the solid connection.

Elf's mainline variation for  

makes the solid connection, again preventing the White atari there. - penetrate the Black corner. makes a kind of two space extension, and the White wall is still insecure. pushes along the fourth line, blocks, and then hanes.

Elf's mainline variation for , continued  

at a, at b

extends on the fourth line, pushes, and block again. protects against the cut, and stands. cuts, and the fight is on.

Elf's mainline variation for  

captures the stone, also preventing the atari at a. After the probe and crosscut, preventing the White atari at a becomes a prime objective for Black. The Black shape with five stones surrounding the eye formed by capturing the single White stone appears in textbooks as a good way for White to sacrifice that stone. Elf really doesn't seem to like that shape.

penetrates the corner, cutting off the stone. gets the cut in the bottom right. That is a rare treat, as the bots love the solid connection so much. and push along the fourth line, building a wall, then extends on the top side. takes the double keima, and then protects White's incipient territorial moyo.

Back to the game.

Big moves  

The solid connection, , is big. So is capturing the stone in a ladder. , although joseki, is a mistake, according to Elf, losing 10% to par. Black should save the stone.

Saving Private  

Elf recommends , not only saving the stone but threatening the stones as well. - play the tenuki joseki in the bottom right.

Back to the game.

After Elf gives Black a 10½% chance of winning (24.3k playouts). White makes a few minor errors in the bottom left corner, but maintains the 90% lead after Black blunders.

Ladder breaker  

is a ladder breaker. parries it, but Elf thinks that 27 is 7½% better. extends on the fifth line, offering the corner for outside strength. Elf regards the solid connection at 29 to be 5% better.

Blunders  

Elf regards as a minor error, losing 7% to the a. But is a blunder, giving up 18% to par. Even though Black can threaten to break out with sente, what he gains in the corner is not worth the outside strength that White gets in exchange, according to Elf. Elf says that should take gote and make the ladder with b. The two space extension in the actual game loses 13% to par, a blunder when White's winrate is aroundd 90%.

Elf's judgement of the play in the top right corner is particularly instructive, as White's sacrifice comes right out of the textbooks.