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Subject: Re: CCC Retirement

Author: Stuart Cracraft

Date: 09:57:32 01/16/06

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On January 16, 2006 at 11:32:57, Robert Hyatt wrote:

>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).

Yes - I need to add other test suites besides WAC, but my initial goal was
simply to get to the point of reasonable tactical play. I do not think
266/300 on WAC at 5 seconds a move on a 3.2ghz P4 is yet there.

Beyond this, it is a question of how much I can do at one time and single
goals are easier for me. Trying to handle multiple simultaneous goals is
not something that I wish to do in my hobby.

I am currently adding terminal node full evaluation and surprised it has not
worsened my WAC results but improved them slightly. For example, I have
mobility, some pawn generation, a little king safety, etc. These helped do
a couple percent better on WAC.

That's the kind of conservative improvement I am looking for. I am past
the point of believing that something I add is going to have a 10 position
or 20 position improvement at this stage.

Stuart



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