caranthir:
@Farkas In the SGF I tried to show that white is already alive in seki after b D18, w C19, b E19, and the sequence is therefore a failure (in gote even) for black. Adding w E17 after that gains nothing for white. The problem was incorrect before in that b D18, w C19, b E19 was shown to be a success for black (which was the whole point of my demonstration), but was thereafter fixed.

caranthir:
SGF

caranthir:
After b D18, w C19, b E19, the space is one too large to be reduced to hana-roku, so w lives still. (SGF)

Nicolas:
I think that black can also play O2 or P3 instead of P1 for the last move (even if white's ko threat is less good in case of P1)