Go Paradoxes

British Go Journal No. 62. July 1984. Page 23.

Andrew Grant

Fujimuras position

It isnt very often that a position arises in actual play that is not covered by the rules. In fact, there are so many weird and wonderful rulings to cover anomalous positions that it has only happened once (to my knowledge) since the Nihon Kiins Laws of Go were formulated. This was in 1954, in a five-stone handicap teaching game played by a professional 5-Dan named Fujimura.

Diagram 1

Diagram 2

The position is shown in Dia 1 with Black to play. Blacks best option seemed to be the sequence in Dia 2 leading to sente seki, Black could see no way to capture the White corner stones. (Black may have to play 3 to the left of 4, making a gote seki to prevent a ko.) Unfortunately this left Black too far behind in the game, so he resigned.

Diagram 3

Diagram 4 4 pass, 6 pass, 8 at , 10 at .

Fujimura refused to accept this, claiming that Black could win by playing as in Dia 3. This looks just like another seki, and an inferior one at that; but Fujimura argued that the white stones were all dead. He pointed out that after Dia 3, White could do nothing more, so Black could finish the rest of the game. He could the go round the board eliminating all of White's ko threats, and finally play the sequence in Dia 4 which produces a ko. White has no ko threats, so he loses his stones.

The position behaves similarly to the "bent four in the corner" (for an explanation of the bent four rule, see "Life and Death" in BGJ 57). As the bent four is unconditionally dead under Japanese rules, Fujimura argued in an article in "Kido" magazine that the corner stones should be unconditionally dead as in Dia 3. and that this should be made a new rule.

It was quickly pointed out that Black would not necessarily be able to erase all Whites ko threats; a seki or double ko both provide unerasable threats, so a ruling making Fujimura's group unconditionally dead would not always be logically justifiable. (The same is of course true of the bent four rule).

A year-long controversy on this question led the Nihon Kiin to look into it. They decided that the bent four rule could not be extended by analogy, but that their rules committee should draft a new rule to cover Fujimuras position.

Thirty years later, the new rule has still not been made, and the whole question seems to have been quietly forgotten.

Oh well, I suppose it isnt likely to happen again.