After joseki：capturing race of corner and edge 2

Continuation from the Previous Article (Link: https://www.1200igosharing.blog/post/%E5%B7%A5%E5%85%B7%E7%B3%BB%E5%88%97%EF%BC%9A%E9%82%8A%E8%88%87%E8%A7%92%E7%9A%84%E5%B0%8D%E6%AE%BA)

This article will study the timing of the move at point A, to begin I will explain the reason for investigating this issue.

Locally speaking, if Black plays moves 1 and 3, the White corner could not make two eyes. However, if played too early, White can bend and capture the Black stones on the side.

If Black plays the move too late, White can counter to play hane and connect, not only living in the corner but also significantly weakening Black's right side.

On the other hand, White does not want to reinforce the corner too early, as White hopes that Black will play more moves on the second line, reducing the vitality of White's stones in the center if Black hane too early. This is why studying the timing of the bend is important.

When Black has only four stones, bending and connecting is too early, but this problem is quite deceptive.

https://www.101weiqi.com/q/403576/

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After Black 1 pushes and then clamps at 3, White cannot capture Black cleanly.

If White stands at 4, Black cuts at 5 to create a ko.

If White connects at 4, Black has the placement move at 5. Q19 is tesuji, if playing at the move at T18, atari is only an endgame move; 4 liberties versus 4 liberties, with White playing first.

Connecting at 4 is the strongest move for White.

Next, White should stand at 1.

After White connects at 3, Black cannot connect at P19 (Oiotoshi).

If Black connects to form a straight three, the local position becomes an approach ko. In conclusion, if Black crawls with four stones, then hane and connecting is too early.

When Black has crawled with five stones, then hane and connecting is appropriate.

When White bends at 1, Black can play 2 to effectively kill.

If White retreats at 3, Black hane at 4, black wins.

However, caution is needed against White's move to connect at 4

If Black hane at 1, it falls into a trap!

Black can only create a ko to capture White, but the value of White's bend at 2 is huge, leading to a loss for Black.

If White connects at 4, Black should continue to crawl outside at 5. Black needs to crawl enough to have seven stones before making a move to kill White (refer to the previous article for life and death details).

After Black 5, if White reinforces the corner, Black's sente moves at 1 and 3 are sufficient for profit, and in the future, the bend and connect on the top side will be Black's privilege, leaving White with only 6 points.

Generally, AI suggests that White should be unyielding and that spending two moves to live in the small corner is less advantageous than playing the bend at 4 and then another move on the outside. Therefore, from White's perspective, if White does not want to trade (although this trade, resulting in a dead corner, can be fully considered), then when Black crawls with four stones, White should seize the opportunity to hane and connect on the upper right corner.

Conclusion: From Black's perspective, Black should bend and connect after crawling with five stones unless in special cases where the upper side cannot be allowed to be bent by White. Otherwise, after Black bends and connects, capturing the corner with one move is satisfactory. From White's perspective, White should consider whether to counter hane and connect earlier, whether to trade, or whether to reluctantly live.

However, the mystery of this local position is not completely resolved yet, and AI does not recommend black to hane and connect at this moment...

AI recommends the sequence of moves 1-5, which represents AI's ultimate pursuit of efficiency. When to choose this variation is a complex issue that will be explained in the next article.