Author: Christophe Theron
Date: 20:58:44 10/07/99
Go up one level in this thread
On October 07, 1999 at 22:55:42, Dave Gomboc wrote:
>On October 07, 1999 at 00:58:07, Christophe Theron wrote:
>
>>On October 06, 1999 at 21:52:28, Nicolas Carrasco wrote:
>>
>>>Now I am examining how my Alpha Beta cut off's are working!
>>>
>>>I would be extreamly pleased to know how many nodes your chess engine make at
>>>the initial position (if possible without move ordering) at the following
>>>depths:
>>
>>For Chess Tiger 12.0 (with move ordering and selection) the results are:
>>
>>2- 46
>>3- 606
>>4- 2088
>>5- 3929
>>6- 10102
>>7- 31441
>>
>>
>> Christophe
>
>Your odd/even effect is quite a bit larger than I'm used to seeing. Asymmetric
>pruning?
>
>Dave
The odd/even effect depends on the position. For example going from level 2 to
level 3 takes a lot of work, apparently because the first sequence of capture
begins, or maybe checks (?). At that time the move ordering stored from the
previous level becomes completely wrong apparently.
If you look at the increasing (cumulative) branching factor you get:
2 to 3: 14.0x
3 to 4: 3.4x
4 to 5: 1.9x
5 to 6: 2.6x
6 to 7: 3.1x
So this is not an odd/even effect. Sometimes the odd to even is high, but
sometimes the even to odd is higher.
As I said, the behaviour is different in each position. Also, at deeper depth it
tends to be smaller.
Christophe
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