定石 Research Part 2

基本图

For this situation, 白3 is a rare experimental move. 黑 can rougly respond at A-C. On the last article, choice A is rejected because of bad corner aiji.

黑4 扳 is the first instinct. But after 白7, 黑 needs to buckle down and do some serious calculation on whether black can cut on B or not.

Black needs to consider whether to extend at A first or join directly at B. As a spoiler, extend at A does not work well for black.

Due to ko material at A, white can win the ko fight in the corner. This variation is unsuccessful for black.

黑1 join is correct. After 黑3, if white wants to continue to fight in the corner can play either A or B. Although calculation is rather tedious, both variations are not favorable for white.

白15 = A

Due to ko material at B for black, white can not win the corner ko fight. Now we can see why extension at P11 is not good for black.

白1 = A

Sequence up to 白11 is rather straight forward. 黑12 take is correct. Black should be careful with 白13.
黑1 removes ko is overly fierce. Sequence to 黑9 we have a rare seki with white group without an eye.

黑1 is correct. White group is unconditionally surroundered.

Key points:

1) White can't fight head on against black with either A or B. However, white can live in the corner with C.

2) Black doesn't have an immediate suitable ladder breaker for triangle black seed. D is not a ladder breaker.

3) White can actually defend against marked black seed from escaping with E.

Conclude: 基本图 option B variation is not favorable for black.

Even if black can escape with 黑1, black group will transform into a spectacular art piece.