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Subject: Re: Correct values if all moves are pruned?

Author: Severi Salminen

Date: 08:58:32 01/06/01

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>In fail-hard alpha-beta, the correct value for a fail-low is alpha.
>
>However, if you are using fail-soft, you should return the best bound that you
>are confident in. In this case, that bound would be material+gain+FMARGIN. This
>is not an estimate of what the score will be, but an upper bound on how high the
>score might be.

Well this is what I wanted, thanks! Now I just have to try if it really works in
practice...

>>2.I'm using now SEE and I wonder what is the "correct" value to return from
>>qsearch if I prune all captures: if(eval()+seescore(move)+MARGIN<=alpha)? Now I
>>just return alpha. If all moves result a score<=alpha should I return
>>eval+seescore or something else.
>
>Here as well, treat the pruned move as if it had the score eval+see+MARGIN,
>which is the best bound you get without search. If you return alpha you lose
>information about how bad this position is, and if you return eval+see the bound
>will often be to optimistic.

alpha seems to work, but I'll try eval+see+margin also.

>/Johan Melin




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