Seki in area and territory scoring

Seki  

Black can turn the corner into a seki with and . This is the optimal solution to the problem, regardless of whether area scoring or territory scoring is used.

Under area scoring, ignoring stones already on the board, Black has one point while White has two points. Under territory scoring, both Black and White has no points, because the points inside a seki are not counted.

Seki  

Suppose Black subsequently makes an exchange of and to "ensure" the seki. Under area scoring, this exchange costs nothing because White gains one prisoner at the expense of reducing the territory by one point. However, under territory scoring, this exchange causes Black to lose one point because White gains one prisoner, even though both groups still have zero points in territory.

( uses up a big ko threat, but at the same time prevents White's two small ko threats. See Beginner Exercise 332/Solution)

Seki  

This alternate sequence also results in a seki. However, using the same argument as above, it is inferior to the solution by one point if territory scoring is used.