Author: Robert Hyatt
Date: 11:59:37 09/28/04
Go up one level in this thread
On September 28, 2004 at 13:59:58, Steve Maughan wrote:
>Bob,
>
>>What I do is this: When I get a hash hit, and the draft is not enough to let
>>me stop the search at that point, I then test the table draft against the
>>depth I would use for a null move search at this point. If the table draft is >= that depth, and the table entry says "No way I would fail high here" then
>>there is no point in trying a null-move search, if a normal move search would
>>not fail high...
>
>Interesting - I know that you alluded to this in the past but this is the first
>time the penny has dropped for me as to exactly what you're doing.
>
>So to use example numbers:
>
>Alpha = 100
>Beta = 101
>Depth to Go = 5 ply
>
>Hash Score = 50
>Hash Bound = UPPER
>Hash Draft = 4 ply
>
>In this case you'd skip the null move - seems sensible.
>
>Do you know how much is it worth in speedup?
>
>Thanks for the explanation,
>
>Steve
Since WAC141 has been a hot topic, here is crafty with the normal avoid-null
stuff as I explained:
9 3.95 -1.20 1. Kf1 a5 2. Rxh5 gxh5 3. Rxh5 Re1+
4. Kxe1 Nxh5 5. Qg5+ Kf8 6. Qh6+ Kg8
7. Qxh5
9 4.42 +1 1. Qxf4!!
9 4.67 +3 1. Qxf4!!
9 5.16 +M 1. Qxf4!!
9 50.78 Mat06 1. Qxf4 Bxf4 2. Rxh5 gxh5 3. Rxh5 Bh6
4. Rxh6 Qh2+ 5. Kxh2 Kf8 6. Rh8#
9-> 50.78 Mat06 1. Qxf4 Bxf4 2. Rxh5 gxh5 3. Rxh5 Bh6
4. Rxh6 Qh2+ 5. Kxh2 Kf8 6. Rh8#
time=50.78 cpu=99% mat=-1 n=79749173 fh=98% nps=1.57M
Here is same thing but without the avoid-null stuff so it always tries a null
move:
9 3.93 -1.20 1. Kf1 a5 2. Rxh5 gxh5 3. Rxh5 Re1+
4. Kxe1 Nxh5 5. Qg5+ Kf8 6. Qh6+ Kg8
7. Qxh5
9 4.40 +1 1. Qxf4!!
9 4.75 +3 1. Qxf4!!
9 5.22 +M 1. Qxf4!!
9 49.51 Mat06 1. Qxf4 Bxf4 2. Rxh5 gxh5 3. Rxh5 Bh6
4. Rxh6 Qh2+ 5. Kxh2 Re2 6. Rh8#
9-> 49.51 Mat06 1. Qxf4 Bxf4 2. Rxh5 gxh5 3. Rxh5 Bh6
4. Rxh6 Qh2+ 5. Kxh2 Re2 6. Rh8#
time=49.51 cpu=99% mat=-1 n=80501452 fh=98% nps=1.63M
So about 1.5% better here. Other positions might be even better...
Note ignore the time and just look at total nodes. second run was not a full
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