Cho Chikun - Kato Masao, 14th Judan 1975 (Triple Ko)
Kato had Black, game was played 1975-07-10, according to gobase.
zinger: A fascinating position! But why is it said that Kato "got lucky"? Black seems to be doing just fine elsewhere on the board.
knott? Can someone explain to me why white simply can't fill the ko with 5? Is it a liberty to many in the example for the white group, I simply don't see the triple ko in this case.
Herman Hiddema: If, instead of taking the ko with at a, white fills the other ko with like this, then black takes with and white takes with . Now the situation is a direct ko. White has only two liberties. Now black has to find a ko threat (b or c, for example).
So white has this option, but if white does not think he can win this ko, or if the loss he has to take to win it is too large, then white is better off retaking at a with .
So white has the option to turn the ko into a direct one, while black has no such option. If white feels that he would lose if he made direct ko, then is the logical option, forcing black either to concede the ko or to reach "no result".
This would also call into question whether Kato "got lucky".