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Subject: Re: What kinds of (forward) prunning are known?

Author: James Robertson

Date: 01:39:51 05/05/00

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On May 05, 2000 at 04:01:13, Jan Pernicka wrote:

>  Hi,
>I would like to know what kinds of pruning are known (and/or used). To be
>correct, I don't mean alfa-beta (which is safe), but I mean rather kinds of
>forward-pruning(FP) (ie: not always safe...). I use this one: when it's last ply
>to horizon AND  eval()>=beta AND not in check THEN return eval(). Are there
>several (probably more brutal (?)) techniques in use (except null-move)?

I think the below is more common as far as fp. The 50 can be any arbitrary
value, but in my opinion it should be at least 25. Just returning eval(), as in
your example, is possible too.

if (depth == 1 && eval() - 50 >= beta && !incheck()) return -quiesce();

Of course you can also try extended futility pruning and even extended extended
futility pruning. I would recommend DarkThought's webpage, as that is where I
learned most about pruning.

James

>
>  Thanks in advance
>
>     Jan
>
>PS: But FP is very risky because (IMHO) better still to play average moves
>    than excellent ones (but to make occasionally immediately loosing moves...)



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