Author: James Swafford
Date: 05:59:37 10/14/02
Go up one level in this thread
On October 14, 2002 at 06:34:43, Vincent Diepeveen wrote:
>On October 14, 2002 at 04:29:41, Daniel Clausen wrote:
>
>>On October 13, 2002 at 22:48:10, Jeremiah Penery wrote:
>>
>>>On October 13, 2002 at 21:40:42, Robert Hyatt wrote:
>>>
>>><snip>
>>>
>>>>You are _totally_ wasting your breath...
>>>
>>>I don't mind too much wasting my breath, as long as some decent discussion comes
>>>from it. :)
>>
>>As if that ever happened on this board when the subject was related to DB. ;)
>>
>>Sargon
>
>the marketing hype created by IBM is so big that we'll never end
>talking about it, like they talked for well over 100 years about
>The Turk automata that won from Napoleon.
>
>it's pretty weird to see people argument that the thing searched 18
>ply fullwidth based upon some mainlines, despite statements and
>theoretical impossibilities to do so :)
Please defend that statment. Why is it theoretically impossible
to search 18 ply full width? Doing some back of the envelope
calculations, I get
4.0^18 = 68.7 B nodes
3.9^18 = 43.6 B nodes
3.8^18 = 27.3 B nodes.
(27.3 B nodes) / (.126 B/Sec) == 217 seconds < 4 minutes.
What's impossible about a bf of 3.8 and a search of 217 seconds?
Note Hsu didn't claim 18 ply _every_ search. He said 12 ply
and up to another 6.
--
James
>
>Amazingly no one ever talks about shredder here. Shredder always shows
>longer mainlines. Some years ago i had a selective search in diep which
>checked the principal variation of diep further.
>
>In the end i threw it out.
>
>Now suppose you have 480 processors idling, i'm so amazed no one can
>understand that in order to get more nodes a second, the only
>important thing, even the chat yesterday Hsu was only talking
>about nodes a second NOT about search depths, it is important to
>give them jobs.
>
>So splitting a position at the end of the pv 1 deeper is not so stupid
>here. The rest is from hashtable and extensions.
>
>The only interesting question this Jeremiah Penery guy should ask himself
>is: "WHAT WAS IBM BUSY DOING?"
>
>Answer: getting as many nodes a second as possible against kasparov
>
>Now how do you get as many as possible CPUs to work in order to
>get more nodes a second, with just a small search depth?
>
>All we know is that even at 11 ply search depths they didn't manage
>to get the full potential of the cpu's. In fact 126 MLN nodes a second
>is a lot less than 480 x 2.25 MLN nodes a second = 1.08 BLN
>
>126 MLN nodes a second is 11.7% from that.
>
>That's basically based upon the last seconds of the 3 minute search.
>
>the first few seconds not many processors had a job out of 480.
>
>So what i do then is to already let them split mainline second ply
>after root. I put a bunch of processors there, despite possibly
>getting a different alfabeta score.
>
>For a 2 processor setup that's horrible for the speedup (gives a
>very bad speedup). For 480 processors it's great, getting them
>busy is very important!
>
>In fact we see from the deepblue paper in 2001 that it was already
>taking processors from a search job if it took a bit too long to
>search it! Then it resplitted and added more cpu's. That automatically
>means that you get a longer PV.
>
>Best regards,
>Vincent
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