BQM 88

The problem.  

unkx80: This position came about from a joseki variant of 3-4 point low approach two-space high pincer two space jump where White is said to have overplayed, see /Background for more.
The BQM here is: how should Black play if descends instead of playing at a? This question was originally brought up for http://GoProblems.com problem 8190. Thanks.

The problem.  

AJP: some playing around seems to show that up to black wins the capturing race.

Alex: Really? Up to , it seems like a pretty clear-cut case of 4 liberties vs. 3. Can Black win by making an eye if he plays at ?

Nick o' time  

Bill: How's this?

Nick o' time (ii)  

Bill: Looks like 5 to 4.

unkx80: I see, thanks. =)

goproblems.com problem 8190  

By the way, this is goproblems.com problem 8190, with the and exchange.

Solution?  

Then a solution that appears to preserve the key stones would be a ko, I suppose.

Bill: Well, losing the corner in a 5 vs. 5 semeai, where White has to actually capture all of Black's stones (semedori), would normally be a good result in the opening. Is sacrificing the corner in semedori better than allowing ?