xela: three stones -> ko? (2008-01-26 00:33) [#4223]

Looking at this diagram and comment:

Three stones (5 at 2)  

With three stones, there are some problems. An attempt by white to hane-tsugi may be met by a throw-in (a liberty stealing tesuji) where white expects to play . The ko that results if white does not connect with does not help white. Therefore at is often correct (a case of One-Two-Three).

I don't understand the remark "the ko... does not help white". It looks to me like black has a lot to lose in such a ko, so it's a picnic for white. Instead, black can play at a, then white can't play at , right?

70.53.51.180: ((no subject)) (2008-01-28 19:47) [#4226]

Karl Knechtel: Black takes the ko first, can extend backwards on the first line for several moves if desired, or just connect at a later... in which case White will eventually have to spend two moves capturing Black's throw-in stone before she can fill (i.e. Black implicitly gets more virtual threats too).