Marfitalu: what is the seki ? at which moves can i observe it ? :)

Hrqls: I didn't know it either - onigoroshi posted a great link some 10 posts below though and now it's all clear to me...:)

Marfitalu: One of the games you and I played had an ugly seki (my fault for not stablizing a group early enough:

http://brainking.com/en/ArchivedGame?g=1678903

In this case, it's actually one move away from being seki, which is still seki. If either the white group at K3 or the black group at K4 place a stone on their shared liberties, no further stones can be placed by either color.Since all surrounding groups are stable (or very likely to be) this would be seki.

headius: It's worth mentioning that I had to settle for a seki because I was greedy and tried to allow your black group to grow before attempting capture. Suddenly it was too big, you cut off my group, and I had to just close the door and write it off.