Hane seki
![[Diagram]](../../diagrams/34/fea3d418bf515238fa89ee73db04095b.png)
Hane seki
Both sides have a string in atari, but for either side, capturing starts a capturing race that the other side can win. Best play is to leave this, therefore it's seki.
(See Seki/Explanation-- Seki With Strings In Atari for more information on why the player who starts the capturing race will lose it.)
Hane sekis are said to have been discovered by Kaise Takaaki? (cf. http://gobase.org/studying/rules/ikeda/?sec=e1060000).
John F. There are several problems here. First the term is hanezeki and the locus classicus of this is Volume 3 of Hayashi Genbi's Gokyo Seimyo (folio 9, verso). He gives one example.
That alone makes the attribution to Kaise Takaaki (though I'm not at all sure that Ikeda says that anyway) wrong by a century, but in fact the earliest known case of hanezeki is the problem called Zheng Li (Wrestling) in the Xuanxuan Qijing (Gateway to All Marvels), so that puts the date back to 1347 straightaway!
Hanezeki is also sometimes wrongly called itazeki from confusion with the first character.