Author: Tony Werten
Date: 00:15:26 07/08/05
Go up one level in this thread
On July 07, 2005 at 15:43:03, Dann Corbit wrote:
>On July 07, 2005 at 15:01:26, Dann Corbit wrote:
>
>>On July 07, 2005 at 14:51:56, Gian-Carlo Pascutto wrote:
>>
>>>On July 07, 2005 at 14:37:19, Dann Corbit wrote:
>>>
>>>>On July 07, 2005 at 14:14:36, Gian-Carlo Pascutto wrote:
>>>>
>>>>>On July 07, 2005 at 13:56:04, Dann Corbit wrote:
>>>>>
>>>>>>On July 07, 2005 at 05:05:50, Gian-Carlo Pascutto wrote:
>>>>>>
>>>>>>>On July 05, 2005 at 14:37:46, Dann Corbit wrote:
>>>>>>>
>>>>>>>>The logfile does not consider the depth on-chip at the leaves. About 6 plies
>>>>>>>>more. So consider it really to be 16-18 plies.
>>>>>>>
>>>>>>>This is quite simply completely wrong, and contradicts what Hsu and Campbell
>>>>>>>published.
>>>>>>>
>>>>>>>http://sjeng.org/ftp/deepblue.pdf
>>>>>>
>>>>>>I read the paper. I was referring to this:
>>>>>>"This typically results in 4- or 5-ply searches plus quiescence in middlegame
>>>>>>positions and somewhat deeper searches in endgames."
>>>>>>
>>>>>>I did not see the contradiction. Can you please point it out ot me?
>>>>>
>>>>>The first number in the logs is the combined depth (excluding quiescence, but
>>>>>nobody counts that). The nominal depth was around 12 ply for the combined
>>>>>search, not 16-18.
>>>>
>>>>Then it represents the estimated maximum combined depth (last column of table
>>>>2)?
>>>
>>>No, that's another matter. Maximum depth is rather meaningless.
>>>
>>>Look at Page 5, 1)b) for the statement that the nominal depth is 12 ply on
>>>average. It's been a while since I read it but basically something like 12 (5)
>>>meant 12 - 5 = 7 ply software, 5 ply hardware, and then extensions and quiescene
>>>search.
>>
>>It makes me wonder why they got such excellent answers, then.
>
>If they could average 100M NPS, then a 3 minute search (40/2 average) would give
>18,000,000,000 {18 billion} nodes and 36 billion at 200 M (and I seem to recall
>a theoretical peak NPS rate of 1 billion).
>
>Since 6^12 = 2,176,782,336 [assuming a branching factor of 6 for pure
>alpha-beta with no pruning whatsoever, no null move, and with 36 moves average
>at each level] a 12 ply search should have taken only 21 seconds at 100 M NPS
>and 10.5 seconds at 200M.
>
>The math does not make sense to me.
Most report a loss of 1 ply of nominal depth for singular extensions (the way
wich DB was using them) Multiply your numbers with the BF (6 it seems) and they
do make sense.
Tony
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