tderz: just arrived here via the thumbnails!
Which are great.
This problem comprises a timing aspect.
If White ever wanted to play here, she has to play now,
i.e. before an A-B exchange.
Not claiming that this is the start of a correct solution.
tderz: if White thus already had exchanged for ,
and then played , Black's natural answer would ensure life for Black and kill White's marked stones.
tderz: the idea would be that after , if Black A, then b-c-damezumari.
However, this is flawed, as Black will never reply to by A, rather live directly with D.
tderz: Let's investigate this exchange.
What's possible frome here on?
tderz: - will not harm and suddenly looks like a vital point
which only has to be verified for liberties.
tderz: White has stunning 7 liberties, which is a lot! One can do a lot in the meantime ...
tderz: if , then surprisingly works and Black has only 4 liberties.
This path seems OK.
tderz: if here, White cuts at , Black cannot atari at B,
and the two corner stones provide the 2nd eye ..
kb: If ...
kb: ...W has a beautiful tesuji at to capture the corner stones.
unkx80: For a while, I was trying to figure out what happens when Black resists with and . But is a tesuji that works for this problem despite the cutting point at .
tderz: whow! and are really strong moves, as is kb's above.
tderz: For completeness: the outside hane is the weakest line of response.
White can now play A or B and win by 7 to 3+sente liberties.