Problem diagram.
Black plays.

Source:
Qi Jing Zhong Miao #458 , an ancient collection of mostly kyu level life and death problems.

Side variation analysis:
   Myron Souris

Solution follows    (or click here to download SGF)

Correct.
Black 1 is the connection tesuji. White 2 is the best try. The sequence up to 7 is forced. White can try 8, but through 13, Black connects, but just barely!

White variation.
(Black 1 is still at White 10.) Capturing the lone stone with White 8 results in a big loss. Through Black 13, White can neither make life nor win the semeai.

Bad timing.
Black 1 is wrong. The order of moves is important! Now White can dodge to 2. If Black still wants to connect, the sequence to 6 is forced. If Black prevents the capture with 7, White captures the 2 stones above with 8. Black loses big.

Black variation.
If Black varies from the previous diagram with 7 here, White counter-cuts at 8. After White 10 the biggest part of Black's groups is cut off.

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