Rectangular Eight In The Corner
Table of contents |
1. No outside liberties
This position is hyperactive. Its value and play depends upon the ko threat situation. If White is komaster she can often make seki with sente.
is the strongest attack.
is the point to avoid ko.
is necessary or White plays there (or to the right of it) to capture the corner.
at
or
will also make a seki, but white would get an extra ko threat.
Nikok34 (KGS) : Can't in this position white can make a bent four in the corner with 1-1?
willemien : No not all bent fours are bent four in the corner if White plays 1-1 and black captures you get the "Not corner bent four 3" on the bent four in the corner page and Black is alive
Nikok34 : Now I see why... thanks
If here,
makes a ten thousand year ko. This result is generally worse for Black than a seki.
at the 2-2 point invites an approach ko.
If after White 5, white gets to play , (the approach move) the ko becomes direct.
in this variation invites a seki. Without
either player can make a throw-in ko.
The Count: This isn't necessarily a mistake, is it? If White has one big ko threat and no others then White can't win the approach ko above, but can win the throw-in ko, and so Black will play and White will make seki which is better than nothing.
2. Outside liberties
Now works. The throw in at
and
are oiotoshi. (If there were no outside liberty,
would be self-atari.)
Conclusion for the endgame
threatens to destroy seven points in sente.
makes seven points in reverse sente. So,
is a typical ko-threat - but it is a bad one. In case of a ko the previous diagram supplies four ko-threats: that's one more than here.
See also
Willemien (temporarely remark) if there are no ko threats and no outside liberties is Black alive in seki or with territory? And if in seki what is the best place to make it an alive group with territory. feel free to remove remark after editing .
Nikok34 : In the second example black is dead in seki if white goes on the 1-1 point, making the bent four in the corner no?
No. -JH