Forum for Ten Thousand Year Ko
Is the problem with starting the ko actually that “the other player will take first” ? [#3119]
I kind of disagree with the way the thousand year ko is described here. If the problem was just that the other player will take the ko first, it would just mean that it's as if the player starting the ko has one less ko threat. In contrast my understanding is that the player who starts the ko has to waste a full move filling the common approach liberty. And this move does nothing apart from making the ko happen, because unlike in an approach ko, it does not improves the “odds” of eventually winning the ko, as it brings both players closer to winning the ko. (Of course just making the ko happen can be valuable in itself, and sufficiently so to be worth playing it.)
Let me know if I'm wrong. The formulation can probably be improved but I hope the idea's there.
Cheers,
Timm
The two are part and parcel of the same thing. Filling the shared liberty to make a more exciting ko means that the opponent gets to take that ko first.
As you point out, the disadvantage of converting the ko may well be worth it to one of the players. So in real life the ten thousand year ko is often fought. But that is another question.
I still disagree sorry. ;) After filling the shared liberty yes, the opponent will take first, but that is accessory. The true cost is that you've either given up sente or ignored a ko threat (more or less the same thing, basically you're one move short).
OK, let's take the first example on the page.
![[Diagram]](diagrams/4/f79917d19582cc910b6eeae4e31a1d93.png)
![[Diagram]](diagrams/37/1ff0b16c7c2cc597d8bb2019d122701d.png)
reaches a position worth 2 points for Black in the corner.
![[Diagram]](diagrams/14/5cea5eae4986f80943c4d5788a1dce76.png)
and 
reach a position worth 9 points for Black.
3 moves separate these positions, so we may think of each play gaining 2 1/3 points, although that is certainly debatable.
But then the opponent takes the ko, gaining 9 points. The main disadvantage lies in letting the opponent take the ko first. As the main page says. :)
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