Computer Chess Club Archives




Subject: Re: Null-Move: Difference between R = 2 and R = 3 in action

Author: Robert Hyatt

Date: 11:56:12 07/21/02

Go up one level in this thread

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.
>>>>I did not ask about single example from endgame but about
>>>>the middle game or about rating improvement.
>>>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.
>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_...

This page took 0.02 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.