Computer Chess Club Archives


Search

Terms

Messages

Subject: Re: no more comments???

Author: Robert Hyatt

Date: 10:20:29 07/23/02

Go up one level in this thread


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?  That is
where I get the benefit.  If just hash move is 1.5 times faster, I would suspect
you are not doing killers right.  IE getting captures into the killer list or
something similar...



>
>I still do not use hash tables to save generating moves and it is another gain
>that I can get from hash tables.

and from killer moves.



>
>Uri



This page took 0.09 seconds to execute

Last modified: Thu, 07 Jul 11 08:48:38 -0700

Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.