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Subject: Re: Extending Checks

Author: Aivaras Juzvikas

Date: 09:04:23 09/11/04

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On September 11, 2004 at 11:47:35, José Carlos wrote:

>On September 10, 2004 at 21:35:58, Stuart Cracraft wrote:
>
>>I read, somewhere, and I forget who, about
>>if 1 legal move, extend 2 ply,
>>2 or more legal moves, then 1 ply.
>>Anyone have any stats on the effects
>>on play of the above instead of
>>always extend 1 legal move. Does it
>>blow up?
>
>
>  I guess you read it in Ed's programming page about Rebel. He does that in
>qsearch, and regarding checking moves generation.
>  I tried his idea in my private program and it didn't work for me. It generated
>too many nodes, but I probably did something wrong.
>
>
>>How do people get around the cost
>>of determining that there is only
>>1 legal move?
>
>
>  If you're in check (you know it before generating moves) you can use a special
>move generator that generates only escapes from check (capturing checking piece,
>moving the king, putting a piece in between...). In that case, you know in
>advance the number of legal moves.

how about puttin a piece in between which uncovers attack on king by another
piece?this legal move generator doesnt look so simple to me somehow, am i
missing smth?

>
>  José C.
>
>
>>For me, that's an expensive operation
>>involving usually dozens of makemove/unmakemove's
>>with a test to see if the king is attacked,
>>at every single node, before doing the search
>>of the 1 move with the increased depth.
>>
>>Only rarely is it just 1 legal move to get
>>out of check. But the determination of that
>>is not rare. It has to be done for every
>>sweep of the moves at each node.
>>
>>Thanks,
>>
>>Stuart



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