Ed?: After the points a are miai to take some white stones.
Velobici: forces white to choose between sacrificing the group of four circled white stones or the group of six marked white stones by threatening both plays at the points marked a.
The position comes from the final game of the 12th Fujitsu Cup between Ma Xiaochun (white) and Yoo Changhyuk (black) played on 7 August 1999. The result was a half point win by black.
The position is discussed in the 45th issue of The Magic of Go