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Subject: Re: EGTB: Until what depth ?

Author: Robert Hyatt

Date: 06:12:04 03/30/01

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On March 29, 2001 at 22:23:44, Christophe Theron wrote:

>On March 29, 2001 at 15:34:45, Alexander Kure 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).
>>>
>>>I don't think that probing the TBs in the first 6/8 plies of the search makes
>>>any sense.
>>>
>>>
>>>    Christophe
>>
>>
>>Hi Christophe,
>>
>>Actually, Nimzo is probing his EGTB (kind of compressed Nalimov EGTB, where only
>>2 bits are stored for the information: win, draw or lost) in the q-search, to
>>look up if the current position is won, lost or a draw.
>>What i meant in my answer to Tony is that Nimzo probes the first 8 plies of the
>>*Nalimov* EGTBs in order to get the right move.
>>
>>Greetings
>>Alex
>
>
>
>I'm sorry Alex, but I do not understand what you mean.
>
>Do you mean that you probe the Nalimov TBs only in the first 8 plies of the
>search, which gives you a MOVE and a distance to mate if there is a TB hit only
>for the first 8 plies, and when you reach deeper ply depths you only get a
>partial information (win/draw/loss), but the partial info takes less time to
>find because it is more compressed (can be fully loaded in memory)?
>
>As you know I'm a little bit new to the EGTB world, so I'm certainly still
>missing some subtle tricks...
>
>
>
>    Christophe


That is correct...



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