Snapback Problem 23

Another yose problem  

After Black decided to play a sente move at . White replied with ; and Black played . That was a mistake. Punish.

MarcGaudet I don't understand why it was a mistake, it stopped white from invading, right?

What happened in the game (continued)  

White was very happy to close the territory and penetrate with in the previous diagram in sente. But White missed an opportunity.

What did not happen in the game  

is bad. threatens the placement at .

Improvement for Black  

connects. Now if , .

 

Qi B can play at 2.