Problem diagram.
Black plays.

Source:
Qi Jing Zhong Miao #305 , an ancient collection of mostly kyu level life and death problems. This problem is one of the simplest in the collection.

Side variation analysis:
   Myron Souris

Solution follows    (or click here to download SGF)

Correct.
Black 1 is a simple but important diagonal tesuji! Through 9, Black's best is a ko.

Black failure.
Notice that Black 5 fails. After 6, White wins the semeai outright.

White failure.
White 2 is greedy. Through 7, Black wins the semeai outright.

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