Xuanxuan Qijing Problem 78 / Solution

Hashimoto solution ( at b)  

threatens to kill White by a next. Then and ! secures another eye in the center.

Ko  

here leads to ko. It is very risky for White because Black takes first and resolving the ko further threatens to kill White. Black has local ko threats at a, b and c. (Hashimoto's first book on the collection was published in 1935 and local ko threats should be considered as part of the solution in those days. So this ko line was not a defect of his solution.)

Variation  

descent is met by . After , a and b are miai.

Failure: under the stones  

After descent, is now a decisive mistake because capture at a is met by at .