Author: Robert Hyatt
Date: 15:28:59 09/28/04
Go up one level in this thread
On September 28, 2004 at 16:33:40, martin fierz wrote: >On September 28, 2004 at 14:59:37, Robert Hyatt wrote: > >>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 >>PGO compile... > >just a very short correction: it's 1.0% better, not 1.5%, do you still have one >of those P4's with math bugs? :-) > >cheers > martin No, that was my math bug. I just did a quick subtract, got 1M and rounded to 1.5%... :)
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