bob_robert:
Lower-right corner: R2-Q2-R1-S1-O1 is marked as incorrect.. But ko threats or not... It's alive and should be considered as correct even if suboptimal.. Am I wrong ?

twohalf:
Lower-right corner: R2-Q2-R1-S1-O1 is marked as incorrect. Is it because of possible indirect ko threats compared with Q3?

caranthir:
w (defender) C18, b D18, w C19, b B19, w D17 lives but is marked incorrect. Compared to w F19 (marked as correct), w D17 is better in that it does not leave b any direct ko threat.