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Subject: Re: no more comments???

Author: Uri Blass

Date: 11:07:15 07/23/02

Go up one level in this thread


On July 23, 2002 at 13:20:29, Robert Hyatt wrote:

>On July 23, 2002 at 12:08:43, Uri Blass wrote:
>
>>On July 23, 2002 at 11:44:29, Robert Hyatt wrote:
>>
>>>On July 23, 2002 at 11:00:26, Uri Blass wrote:
>>>
>>>>On July 22, 2002 at 23:12:15, Robert Hyatt wrote:
>>>>
>>>>>On July 21, 2002 at 14:56:12, Robert Hyatt wrote:
>>>>>
>>>>>>On July 21, 2002 at 14:54:18, Robert Hyatt wrote:
>>>>>>
>>>>>>>On July 21, 2002 at 01:29:38, Uri Blass wrote:
>>>>>>>
>>>>>>>>On July 20, 2002 at 22:20:29, Robert Hyatt wrote:
>>>>>>>>
>>>>>>>>>On July 20, 2002 at 05:55:43, Uri Blass wrote:
>>>>>>>>>
>>>>>>>>>>On July 20, 2002 at 05:47:38, Gian-Carlo Pascutto wrote:
>>>>>>>>>>
>>>>>>>>>>>On July 20, 2002 at 02:52:11, Uri Blass wrote:
>>>>>>>>>>>
>>>>>>>>>>>>My question was not about comparing using hash tables
>>>>>>>>>>>>and not using hash tables but about comparing using hash tables
>>>>>>>>>>>>in the normal way and using hash tables
>>>>>>>>>>>>for all purposes except pruning.
>>>>>>>>>>>
>>>>>>>>>>>In the example given, the move ordering from hashtable is almost
>>>>>>>>>>>irrelevant, so all the gains are due to pruning.
>>>>>>>>>>>
>>>>>>>>>>>--
>>>>>>>>>>>GCP
>>>>>>>>>>
>>>>>>>>>>I did not ask about single example from endgame but about
>>>>>>>>>>the middle game or about rating improvement.
>>>>>>>>>>
>>>>>>>>>>Uri
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>I gave you an answer of sorts.  Best case is fine 70.  3x as many plies.
>>>>>>>>>Middlegame seems to be a factor of 2x in terms of time to reaching a specific
>>>>>>>>>depth.  So a fraction of a ply.  So from early middlegame to endgame sees this
>>>>>>>>>go from a fraction of a ply to (say) 30 additional plies...
>>>>>>>>>
>>>>>>>>>The 30 is important.  It doesn't just happen in fine 70.  It happens in lots
>>>>>>>>>of important king and pawn endings.
>>>>>>>>
>>>>>>>>I know that in simple endgames you can get big improvement thanks to using hash
>>>>>>>>tables for pruning.
>>>>>>>>
>>>>>>>>I also know that you can get a factor of 2 in the middle game from hash tables
>>>>>>>>when the comparison is between using hash tables and not using them.
>>>>>>>>
>>>>>>>>It did not answer my questions.
>>>>>>>>
>>>>>>>>Only Christophe answered them when he explained that I may get 10% speed
>>>>>>>>improvement in the middle game from pruning.
>>>>>>>>
>>>>>>>>Uri
>>>>>>>
>>>>>>>OK... I will take my usual approach and simply give you _real_ data.
>>>>>>>
>>>>>>>Three positions.  The first tactical, the second just a middlegame position
>>>>>>>with no real tactics, the last an endgame (fine70).  All three searched with
>>>>>>>normal hashing, and then using hashing as normal, but not allowing the hash
>>>>>>>stuff to produce a fail high, fail low, or exact score.  It can still tell me
>>>>>>>to avoid a null-move search.  The difference in times, then, is _totally_
>>>>>>>dependent on using the hash scores only, as everything else is identical.
>>>>>>>
>>>>>>>
>>>>>>>                 hashon         hashoff
>>>>>>>Tactical         48 secs        78 secs
>>>>>>>normal          118 secs       183 secs
>>>>>>>fine 70           0 secs        58 secs
>>>>>>>
>>>>>>>In fine 70, both searched to 18 plies.  hash on got right move (kb1
>>>>>>>winning a pawn).  hash off did not get right move.
>>>>>>>
>>>>>>>You can draw your own conclusions.  10% is obviously _way_ too low.  I
>>>>>>>said roughly a factor of two, for middlegames, which is pretty close in
>>>>>>>the first two.  In the last position we _know_ what hashing does.
>>>>>>>
>>>>>>
>>>>>>
>>>>>>I should add, if you _really_ don't think that I answered your question, then
>>>>>>maybe the question you actually _asked_ and the question you _meant_ to ask
>>>>>>are not the same thing.  I believe my previous post shows that I _did_
>>>>>>directly answer the question you asked.  _exactly_...
>>>>>
>>>>>
>>>>>I find it interesting that I answer the question, get accused of not answering
>>>>>the question, then I post _real_ data showing that I answered the question, and
>>>>>the discussion stops cold...
>>>>>
>>>>>why would that be???
>>>>
>>>>I thought that your data about being twice faster was about using big hash
>>>>tables against small hash tables and not about using hash tables for pruning
>>>>relative to using hash tables not for pruning.
>>>
>>>
>>>Think about it for a minute.  If you use a tiny hash on a big search, what
>>>are you doing?  Answer:  Using _no_ hash.  Using the "hash_move" is not a
>>>big winner to me in terms of tree size.  What it lets me do is search faster
>>>because I can try this move first without generating anything, and if I get
>>>a cutoff, I get it with less work and go faster.  If I disable the hash move,
>>>then killers and captures simply work better, and the overall difference is
>>>not very large.  Except for the speed loss.
>>>
>>>If you use history moves for ordering, hashing is not going to be a huge
>>>win if all you get is move ordering from it.  If you do pruning, then the
>>>question changes...
>>
>>I use hash moves only for ordering and it was clearly faster for me(about 1.5
>>times faster).
>>
>>I use also history tables and 2 killer moves.
>
>
>
>Do you do hash move and killer moves _before_ generating legal moves?

No.
I do not do it.
You are right that I can save there time.

I use the information about the number of legal
moves in my search in part of the cases for my extension rules
but even in these cases I can save the number of legal moves
in the hash tables and I may also consider to count the
number of legal moves without generating them before killer moves.

Uri



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