caranthir: Ok, now, I'd say let's not add TherapieGo's variation at least for the time being, because it does seem a little less optimal and is anyway about alternative resistance and not alternative protagonist action from the start. The variation would be surely interesting to explore in another instance of the same position, i.e. another tsumego in another collection, but to add it here would feel a bit heavy. ------ Anyway, thank you @TherapieGo for your find and your continuing research.
TherapieGo: [current position] + A18 What about this answer ? Looks like it's going to end up as a 10,000-year ko. The sequence might look like this : B18 ; A18 ; C18 ; D19 ; C19 ; A16 ; D18 ; E18 ; E19 ; F18 ; G18 ; F19 and 10 000 years ko ?
caranthir: Looks to me like a double-ko-seki situation, though you have probably looked into it more than me. By playing like this, the opponent gives us more forcing moves to solidify the outside, and a ko threat factory, so I'm not sure if it's the best resistance. Were we to add this, there would be a pandemonium of subvariations to be taken care of too. (Though they would be interesting of course. But a lot of extra hassle.) Any opinions from the high dan masters?
Ok, now, I'd say let's not add TherapieGo's variation at least for the time being, because it does seem a little less optimal and is anyway about alternative resistance and not alternative protagonist action from the start. The variation would be surely interesting to explore in another instance of the same position, i.e. another tsumego in another collection, but to add it here would feel a bit heavy. ------ Anyway, thank you @TherapieGo for your find and your continuing research.