No idea where this links from - got here via the Random Page button. My rank beginner eye tells me:
IainK?: Kills? If Black plays a or b then White kills the bottom left group with the other. If Black plays c then White b kills the left 6 stones. If Black plays d then White plays b; after which if Black connects at a he leaves the bottom-left group in atari, but if he lets the stone above a be captured he loses the ability to make a second eye.
fractic: I think you are on the right track but after black d white b it's not as easy as you make it look.
FireclawDrake: Perhaps a more solid play after black d would be white e, trapping black in a connect and die?
fractic: sets up a snapback against the two white stones. But white cleverly counters with her own snapback threat at
.
fractic: Black has no other choic then to go along like this but this leaves the eye at false. A similar play is needed when black starts with c instead of d.
Reuven: At this point it has to be some kind of a ko of course, but how would you go about it? Does -
, b taking first satisfy you?