Ko valuation / 15k v 12k partial review request

Recent 13 x 13 game. I am sure it’s filled with mistakes but the one I’d like analyzed is 85, where I (black) give up the middle L-group to guarantee kill of white in the bottom right. As near as I can tell in post-mortem, the middle L group is worth more than the bottom right because it also presses on white’s territory. (Hence, not just the loss of the group and the middle points, but also the opportunity to press against white’s territory in the upper left.)

Moreover, I had another ko threat at A5 at the time and so didn’t need to kill the ko immediately.

(1) Am I right about the valuation (L group > corner ko kill)
(2) Does anyone see future points of a similar value to the ko (i.e., not just endgame enclosures)?
(3) Is there any hope of invading the upper left? (With or without the central black L group?)


I posted a few game-winning variations and the best endgame I could muster… The difference seems to be rather small, plus it’s not that wise for white to spend 2 moves winning the ko (giving you effectively 3 free moves). Technically you just need to make about 5-6 points per move to make it worthwhile to abandon the ko.


Thank you!