XuanxuanQijingProblem251/Solution

Placement  

Black starts with the placement . This is a difficult move to respond to. If white a or b, black will connect out with e. So white must prevent that. If white c, e or any point further to the right, black will play a and at least one of white's eyes will be false. So the only move that both prevents connecting out and prevents a false eye is d.

Note: f and g are miai, if white plays one in response to , black plays the other.

Forcing moves  

Now, black plays a series of forcing moves. and threaten to connect out, while and threaten to make the eye that would be formed by capturing and a false one. So each of black's responses is forced. After , black will go on to capture...

Capture inside  

After the capture, white must play a immediately. Other moves will result in white's death due to double damezumari, because white doesn't have many liberties on either side.

Sacrifice  

In response to , black sacrifices two stones but can recapture one.

Seeming ko  

After , the situation looks like ko. But black has yet another trick up his sleeve.

Approach  

Black approaches with and , allowing white to capture the black stones inside.

Under the stones  

finally finishes white off, capturing under the stones.