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Subject: Re: Request advice from Chess programmers

Author: John Boyd

Date: 18:28:55 05/04/03

Go up one level in this thread


On May 04, 2003 at 11:41:58, Geoff wrote:


>The results I got for the mobility function  really hammered the nodes/per
>sec and didnt seem to help much in improving its chess knowledge. I might
>try the above idea as it sounds fairly easy to implement.

Yep, I'm thinking about trying it too.  I don't have ANY mobility scoring yet.

>I am pretty sure I have screwed up the code somewhere in the addition of
>killer moves. I will go and have a read of that Bruce Moreland site you
>mentioned see if I can see a mistake I have made

>> Here's a rough benchmark... on a P3-450 my engine (TRACE) searches
>> TSCP's bench
>> position to 6 ply in 4.8 seconds and visits 750,000 nodes. NPS are
>> about
>> 160,000.
>
>My version does 5,230,388 nodes at ply 6 in over 10 seconds on a P4 2.4 Gig
>Machine
>
>I think I have a bit of work to do to catch you up ;-)

HOLY SMOKES!! I'm going to have to get me one of those 2.4Ghz beasties!! :-)

>>NULL move mods
>> When you're ready... but believe me, its easy... look at Bruce
>> Moreland's
>> programming topics site. He gives excellent example code. Also, Faile
>> 1.4.4 uses
>> nullmove and is similar internally to TSCP.
>
> It looks like I need to do the NULL moves mod to get the biggest speed
>improvement. It might not be too bad  once I get into it.

Yep, its easy. I can send you my search() function with the nullmove stuff in
it. It'll also show you how to use the hash tables. Just let me know.

>> >>2. If you are using TSCP's attack() function, rewrite it. Instead of
>> looking for
>> >>pieces which attack a certain square, work outward from the square
>> and look for
>> >>a potential attacker. Its heaps faster.
>
>I coded this up last night, only took me a couple of hours . Here is Toms
>benchmark to ply 6
>
>Nodes: 5230388
>
>Before Mod
>    Best time: 14453 ms
>    Nodes per second: 361889
>
>After Mod
>     Best time: 10375 ms
>     Nodes per second: 504134
>
>Excellent improvement, took me over 500k nps

Great!

>Looks like I really need to tackle hash tables and Null move, both of those
>sound a bit daunting at the moment.
>But I have progressed pretty well so far, my modified version is
>consistently beating Toms orginal version already.

Good work.

>
>One of the things that is irritating me at the moment is when I play a
>tournament between 2 similar versions to measure the improvement I only get
>2 different games even if I play lots of rounds.
>The programs are of course so similar, I just get exact repeat games one for
>black, one for white, ad infinitum.
>I am trying to think of an elegant way to overcome this repeated game
>problem at the moment.

Are you using TSCP 1.81? It has book support and chooses randomly between
lines... so you will get some variety.

>
>Thanks for your help again.

You're welcome.

Ross




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