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Re: [computer-go] Pseudo liberties: Detect 2 unique liberties?


Mark Boon Apr 1, 2009 1:03 PM
Posted in group: Computer Go Archive
I can confirm, with a bit of optimization, counting real liberties is
only marginally slower than counting pseudo-liberties. So there's
really no benefit that I can see from using pseudo liberties.

Mark


On Wed, Apr 1, 2009 at 8:49 AM, Álvaro Begué <alvaro...@gmail.com> wrote:
> When John Tromp and I were thinking about these things in 2007 we
> decided to switch to counting real liberties instead of
> pseudo-liberties. Someone (Rémi?) told us that in the end the
> performance difference wasn't very large, and we verified this.
>
> Álvaro.
>
>
> On Wed, Apr 1, 2009 at 2:08 PM, Isaac Deutsch <i...@gmx.ch> wrote:
>> Hi
>>
>> I'm currently using the method described here to detect if a group is in
>> atari (1 real liberty):
>>
>> http://computer-go.org/pipermail/computer-go/2007-November/012350.html
>>
>> Thus I store the number of pseudo libs, the sum and the sum of squares for
>> each group.
>>
>> Now for heavy playouts, it would be useful if I could somehow modify this so
>> I can easily detect if a group can be put into atari (meaning it has exactly
>> 2 real liberties).
>>
>> My intuition tells me it should be possible by also storing the sum of
>> positions^3. However, I can't quite wrap my head around how to do the check.
>> Has anyone looked into this before, and found an answer? I like this approach
>> because it's so easy and fast.
>>
>> Regards,
>> Isaac
>> --
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