> Bent four is hard for me. Is this right?
> Without tree search, right playout result is maybe
>
> If many ko threats are left, and white to move.
> W lib is 4, W is 0% live.
> W lib is 5, W is 66% live. white has to play J8.
> W lib >= 6, W is 66% live.
>
> If there is no ko threat, and white to move.
> W lib is 4, W is 0% live.
> W lib is 5, W is 100% live. white has to play J8.
> W lib >= 6, W is 100% live.
Hello Hiroshi,
here is what I think about the status of the top right corner, assuming that
white goes first.
(If Black goes first he just takes one liberty and reduces it to a case where
White goes next)
The basic sequence inside is White J8, Black G8 capture, White H9. White can
choose to start this sequence at any time. Black has no good first move inside
- Black always plays the outside liberties until W starts to play inside.
What happens next depends on both the number of outside liberties and on ko
threats.
1. with 2 or fewer liberties, W loses the semeai
2. with 3 or 4 liberties, it becomes a ko where white needs to find one more ko
threat than black. After the basic sequence, black takes a liberty, then White
needs to throw in at J8, black captures at J9, and white needs to find the
first threat.
3. with 5 or more liberties, white threatens to extend on J9 instead of throw
in at J8, and win the semeai without ko. Therefore, after the basic sequence,
Black needs to start the ko immediately by throwing in at J9. White captures
first, and black makes the first ko threat.
I hope this makes it a little bit clearer.
In the examples I made from your first example, B has ko threats in the other
corner, which W can eliminate by playing there first. W has 0 ko threats, and
no way to create threats even with two moves.
Regarding percentages in playouts, I guess it depends on how your program
handles taking liberties, and playing ko threats. I am pretty sure that Fuego
does not understand any of this, and it just gets “solved" in the tree search.
However if this comes up earlier in the game, maybe with still many liberties,
I have no idea how it will distort things.
Martin_______________________________________________
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