The referee declared the game a draw at move 276 and an immediate rematch took place. Jiang Weijie won the rematch by resignation.
A different kind of quadruple ko
Last time, there were four separate kos between two entangled groups, and there was no way for either player to avoid the situation.
However, this time, there was a double ko on the right side as well as two half point (endgame) kos elsewhere on the board.
Why did Lee Sedol fight the ko?
Black (Lee) was winning by 1.5 points (not counting the kos).
However, if Lee wanted to avoid the ko fight, he’d have to spend another move on the right side to eliminate the ko, which would lose one point.
Furthermore, White would then be able to win both the half point kos, so Jiang would win the game by half a point.
Lee counted and realized that he couldn’t avoid the ko, without losing the game, so he played the quadruple ko and the game was ruled a draw.
If Lee had been winning the game by a margin of 2.5 points or more, he would have been able to avoid the quadruple ko and still win the game.
The Chinese A League
Lee Sedol is the team captain for Guangxi Province in the Chinese A League. He plays in the Chinese Weiqi League as what they call a ‘mercenary’ (what we might call an import in English). Jiang Weijie is also the captain of his team, Shandong Province.
Lightning strikes twice
This sort of triple or quadruple ko (which voids a game under some rulesets) is extremely rare, but this is already the second such event involving Lee Sedol.
There’s a great deal of complicated, large scale fighting in Lee’s games, and that might increase the likelihood of these sorts of shapes arising.
For further reading, here’s a link to Younggil’s commentary of the last quadruple ko game, between Lee Sedol and Gu Li.
In 2013, there was also an ‘Eternal Life’ game between Ahn Seongjun 5p and Choi Cheolhan 9p, which some readers might be interested in.
Is a triple ko or quadruple ko unlucky?
Traditionally a triple ko is thought to be unlucky. This is because of a story (and it probably is just a story) involving a triple ko game between Honinbo Sansa and Kashio Rigen (also probably not a real person) in 1582.
Supposedly, a game which ended in a triple ko was played in the presence of the warlord Nobunaga. Shortly afterwards, one of Nobunaga’s allies turned against him, surrounded the monastery where he was staying and Nobunaga lost his life.
There’s historical evidence for the part about Nobunaga and his ally, but not for the story about Honinbo Sansa and the triple ko game.
“The famous ‘Legend of the Triple Ko at Honnoji Temple’ is almost certainly an invention of the later Go world. There is no historical evidence for it in text where it should appear, such as the Nobunaga Koki, the annals of Nobunaga’s reign. The first reference to the legend was over 100 years later…” – The Go Companion, page 195.
However, the story lives on and there’s even a supposed game record featuring a triple ko floating around on the internet.
Because of this, a triple ko is still regarded as unlucky, at least in Asia.
A quadruple ko is only slightly different, but one thing we can say for sure is that it’s unlucky for Lee Sedol. In both the games he’s played which involved a quadruple ko, the referee intervened and he lost the mandated rematch.
Game record – Quadruple ko
Lee Sedol vs Jiang Weijie
Here’s the link to the rematch, which Jiang Weijie won, for anyone who’s interested.