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Subject: Re: why don't chess engines simplify enough

Author: James Swafford

Date: 05:40:39 01/25/06

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On January 25, 2006 at 04:19:17, Ross Boyd wrote:

>On January 25, 2006 at 01:34:54, Joseph Ciarrochi wrote:
>
>>We learn early on that if we have a winning advantage, we want to eliminate any
>>chance of counterplay by our openent. We usually would like to simplify the
>>position.
>>
>>I've noticed that rybka and other engines often won't simplify the position , if
>>there is the slightest loss of points (say -.1). So lets say black and white
>>still have q's on the board, but black has a clearly winning advantage (+6). if
>>black gets the chance, it should trade those queens (assume this really is a
>>good idea).
>>
>>
>>Are there any engines that will do this?, i.e., take a slight decrease in
>>advantage to simplify the position and garuntee the win?
>
>Hiarcs springs to mind.... it will occasionally throw away material to simplify
>into an easy win. You will see this kind of behaviour in most engines that use
>egtbs... ie. they will throw wood to get a tablebase win/mate.
>

I've observed this behaviour (even in my own stuff), and it's not because
of any programming-for-simplification.  It's just a side effect of the
search seeing a win from TB's with N men on the board, and having to
throw one away to reach that position since it doesn't have N+1 men TB's.

Not quite the same as gracefully simplifiying down...

--
James



>In my engine I don't do anything to simplify (apart from the above)... although,
>I have an idea in the pipeline which I call "waypoints" which is a type of late
>middle-game recognizer code that will actively force the search towards easily
>won endgames. It will be used mainly for hyper-aggressive endgame pruning. I
>expect its play to appear stark raving mad to the trained eye - even though it
>should still retain the win.
>
>On the flip side, when its losing/defending it will doggedly try to keep the
>game complicated, uncertain and in uncharted waters.
>
>Well, that's the idea in theory...
>
>Ross



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