XuanxuanQijingProblem57/Attempts

Attempt 1

looks to be key  

Ko  

If white 4 from above variation plays here, there is no ko.  

If w connect, black kill 5 stones  

[edit]

Attempt 2

How about this for ko.  

OK, my previous attempt was wrong. Continuing after black 9.  

White group is safe.  

[edit]

Attempt 3

Black gets either a or b for the ko.  

If white 4 answers here..  

Again, ko.  

If white 4 makes the first eye here..  

Black gets either a or b to kill the white group.