posetcay: E18-F18-E19-D19-C19-F19-A18-A16-B19: Black is alive in the corner with 2 points while white has 4 points on the side (2 territory+ 2 prisoners)
E18-F18-C19-E19-A18-A16-B19: Black is alive in the corner with 2 points while white has 2 points on the side (1 territory+ 1 prisoner)
Therefore if black extends at E19 it is a loss of 2 points.
caranthir: Oh, I didn't first know what extension you were talking about. I still think that one could play that points-losing variation in some rare cases where one wants to keep more on the sente side and also leave behind less ko threats. Even though that variation does look a little stupid to me :)
posetcay: While extending the stone does live, it loses points compared to the optimal answer, so I think in an advanced collection like this it might not be good enough.
E18-F18-E19-D19-C19-F19-A18-A16-B19: Black is alive in the corner with 2 points while white has 4 points on the side (2 territory+ 2 prisoners) E18-F18-C19-E19-A18-A16-B19: Black is alive in the corner with 2 points while white has 2 points on the side (1 territory+ 1 prisoner) Therefore if black extends at E19 it is a loss of 2 points.