This position was adapted from a position that appeared in a professional game. This game was described in the book 《实战的魔术》 (ISBN: 7-5337-0567-2) by Yamabe Toshiro. (Original Japanese edition: 実戦の魔術, ISBN:9784818201965)
and can force a ko for life. Black has some ko-threats in the vicinity of a.
If destroys the eye at the bottom, then and captures six White stones.