Author: Robert Hyatt
Date: 08:32:57 01/16/06
Go up one level in this thread
On January 14, 2006 at 23:35:15, Stuart Cracraft wrote:
>On January 14, 2006 at 17:27:00, GeoffW wrote:
>
>>Hi Stuart
>>
>>>Where is this Winboard forum?
>>
>>http://wbforum.volker-pittlik.name/
>
>** Thanks
>>
>>You might like it as there is a specific programming sub forum
>>
>>>
>>>Also - why haven't they turned to Arena?
>>>
>>Lots of old loyal fans for Winboard, and apparently Winboard is more robust when
>>used with the Internet chess servers. I only use Arena myself, but i know that
>>Alessandro is updating Winboard to add some interesting new stuff
>>
>>
>>>Arena doesn't have ability to play a program on ICS/FICS automatically?
>>It does have this feature, it basicially works but is a bit buggy from what I
>>recollect other people saying
>>
>>Changing subject, your post a while back where you posted a snippet of code for
>>late move reductions, any chance you could repost it please as I cant find it
>>now.
>>The reason I ask is I added the same trick to my prog, it seemed great at first
>>as it reduced node count hugeley, now I have played a few games with it though
>>it is badly reducing strength
>
>I have this in my main PVS loop (after the first move has been searched
>before the loop.) The legals includes the pre-loop move. So I have to have
>searched 4 or more legal moves, not pseudo-legal, before I can start tossing
>moves out as long as no prune is set, no extensions and no reductions.
>
>#ifdef LATEMOVEREDUCTION
> // late move reduction, i.e. the poorly named history pruning, follows.
> if (prune == 0 && extension == 0 && reduction == 0 && legals > 3 &&
>
>!(sml[mvi].cap!=0||sml[mvi].pro!=0||hheuristic[stm][sml[mvi].from][sml[mvi].to]>0))
>{
> extension=-1;
> }
>#endif
>
>>
>>Have you got some results now as to the effect it had on your program ?
>>
>> Regards Geoff
>
>Here's the test I did to respond to your question:
>
>with Late Move Reduction:
>
> 1 second per move, 300 Win-at-Chess position, score=206.
>
>without Late Move Reduction:
>
> score=204
>
>I know this is too close to call because it is < 1% difference.
>At 5 seconds per move, the difference was 2% in favor of LMR.
>
>But, and this is the big thing, I've wanted to call my program
>"selective" for a long time - and now I can. Sounds petty, but it's fun.
>
>Stuart
Let me add that WAC is but one test you need to do. You can rip out most of
your positional evaluation code and do better at WAC as they are mainly
tactical. (they are all tactical, but some programs solve a few on purely
positional grounds, luckily enough). Doing better at tactical tests might be
accompanied by doing worse in actual games, unless that is tested as well...
Deciding whether a change is good or bad is non-trivial. I've certainly made
enough of these decisions wrongly to learn to be more careful in the future
(hence the current eval rewrite to eliminate lots of garbage).
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