Author: Christophe Theron
Date: 19:38:33 03/29/01
Go up one level in this thread
On March 29, 2001 at 16:01:51, Tony Werten wrote:
>On March 29, 2001 at 15:12:21, Christophe Theron wrote:
>
>>On March 29, 2001 at 14:39:34, Tony Werten wrote:
>>
>>>On March 29, 2001 at 14:21:16, Christophe Theron wrote:
>>>
>>>>On March 29, 2001 at 13:49:06, Tony Werten wrote:
>>>>
>>>>>On March 29, 2001 at 13:31:59, Christophe Theron wrote:
>>>>>
>>>>>>On March 29, 2001 at 09:14:57, Robert Hyatt wrote:
>>>>>>
>>>>>>>On March 29, 2001 at 06:22:13, Jouni Uski wrote:
>>>>>>>
>>>>>>>>On March 29, 2001 at 06:17:50, Alexander Kure wrote:
>>>>>>>>
>>>>>>>>>On March 29, 2001 at 04:37:19, Tony Werten wrote:
>>>>>>>>>
>>>>>>>>>>Hi all,
>>>>>>>>>>
>>>>>>>>>>until what depth do various programs probe the tablebases ?
>>>>>>>>>>
>>>>>>>>>>cheers,
>>>>>>>>>>
>>>>>>>>>>Tony
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>Hi Tony,
>>>>>>>>>
>>>>>>>>>In London 2000, I let Nimzo 8 play with a depth of 6 plies, but later I came to
>>>>>>>>>the conclusion that 8 plies might be better overall. This is indeed the default
>>>>>>>>>setting of NimzoX and Varguz playing on ICC.
>>>>>>>>>
>>>>>>>>>Greetings
>>>>>>>>>Alex
>>>>>>>>
>>>>>>>>Sorry one stupid question: is this the first or last 6/8 plys?
>>>>>>>>
>>>>>>>>Jouni
>>>>>>>
>>>>>>>
>>>>>>>His statement would make no sense if it were the _last_ 6-8 plies. Those
>>>>>>>are the ones that kill performance if you aren't careful. The first 6-8 plies
>>>>>>>don't cost a thing.
>>>>>>
>>>>>>
>>>>>>
>>>>>>But it could also mean it probes TBs in all the plies except the last 6/8.
>>>>>>
>>>>>>Meaning that if Nimzo is doing a X plies search, then the program probes the TBs
>>>>>>in the tree for all nodes that have a distance from the root below or equal to
>>>>>>X-6 (or X-8).
>>>>>
>>>>>Could be but that would mean, with an average depth of 10 to 12, you'd be
>>>>>probing the first 4 to 6 ply. I mean, it helps but it could help more.
>>>>>
>>>>>That is, not counting extensions, but you if you search 10 ply, you don't know (
>>>>>at ply 8 ) how many plies are still coming.
>>>>>
>>>>>cheers,
>>>>>
>>>>>Tony
>>>>
>>>>
>>>>But you know how many plies you have done since the root position...
>>>
>>>2 possibilities:
>>>- We are talking about different things
>>>- I don't get it
>>>
>>>Might be both.
>>>
>>>Tony
>>
>>
>>You don't know how many extensions you are going to do, so you just ignore
>>extensions and assume you are going to search full width the same number of
>>plies as your iteration number.
>>
>>So at iteration 10, stop probing TBs after two moves from the root (assuming
>>like Nimzo that you don't probe in the last 8 plies of search).
>>
>>That is why I say "you know how many plies you have done since the root
>>position...".
>
>But then you don't have almost no depths where you probe. (In your example only
>ply 1 and 2 )
Yes, but your NPS does not go too low then.
It's a compromise between speed of search and accuracy of the evaluation.
Don't forget that accessing a TB slot can be as expensive as searching 1000
nodes (depends on your program). And that many TB accesses are just a waste of
time because they are not going to have any influence on your main line.
I'm not saying that 8 plies like in Nimzo is the right number (actually I'm not
even sure that Nimzo does it this way).
In Tiger I stop accessing the tablebases a few plies before I reach the horizon.
If I don't do that the program gets much weaker because of the dramatically
slower NPS.
Christophe
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