iterative deepening & a/b pruning

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iterative deepening & a/b pruning

Postby Folkert van Heusden » 22 Jul 2013, 07:25

Hi,

When performing iterative deepening, why shouldn't I re-use the calculated alpha/beta of the previous iteration?
I googled this and found some people saying "don't do this, use -inf/+inf" but I don't understand why.


regards
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Re: iterative deepening & a/b pruning

Postby Ron Murawski » 23 Jul 2013, 05:01

Hi Folkert,

When you finish a search to an arbitrary depth, you have no alpha/beta bounds, you have an exact value -- let's call this value 'score'. I use (score-margin) as the new alpha and (score+margin) as the new beta. where 'margin' is somewhere between 15 to 50 centipawns.

Ron
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Re: iterative deepening & a/b pruning

Postby Folkert van Heusden » 23 Jul 2013, 12:47

Ron Murawski wrote:When you finish a search to an arbitrary depth, you have no alpha/beta bounds, you have an exact value -- let's call this value 'score'. I use (score-margin) as the new alpha and (score+margin) as the new beta. where 'margin' is somewhere between 15 to 50 centipawns.


Ah indeed. I must experiment with this. Thanks!
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