Cho Chikun Advanced no. 13

[Clairo]

I'm stuck on the attached life and death problem -- would appreciate some help! Black to play (no.13 from this one: https://tsumego.tasuki.org/books/cho-3-advanced.pdf)

[Joaz Banbeck]

[dhu163]

Hint:

ah, but you shouldn't threaten the throw in as that only gives one forcing move whereas atari gives two. If you want to save cutting stones, either use the forcing moves or just don't save the cutting stone.

Hint2:

Despite such a small position, even with the correct answer there are perhaps 6+ W responses you have to check.

[Clairo]

Still cannot see it

[Harleqin]

You can go one space further on the first line.

[Clairo]

Ok I think I got it, finally. Thanks for the hints

[tcelferact]

Thanks to all posters, I found this really helpful! However, I think the best refutation for white is missing.

I believe if white plays the wedge at J18 after black's J19 then white can live on the right. Black does kill on the left though.

Please let me know if you think I've missed something!