Author: Nagendra Singh Tomar
Date: 18:27:18 10/25/02
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On October 25, 2002 at 20:10:17, Nagendra Singh Tomar wrote:
>Hello all,
>
>If we are using PVS search and assume that at the root, the 2nd move (searched
>with a zero window) turns out to be the best move. Since we are passing a zero
>window down to that subtree, at all the plys below, it will either fail-low or
>fail-high, so none of the plies will update the PV. In this case we will get a
>pv length of 1 (with only the root move in the PV).
>Is this true whenever any move other than the first move tried at the root lies
>on the PV.
>How do we fill the PV in such cases ? using trans table ?
>
>regds
>tomar
score = -alphabeta(board, -alpha-1, -alpha, depth-1);
if(score > alpha && score < beta)
{
score = -alphabeta(board, -beta, -score, depth-1);
OR
score = -alphabeta(board, -beta, -score+1, depth-1);
}
since the zero window search failed high and it returns
score, this means that the true score is >= score.
Now when we do a wide window search, if we want to store the PV
properly we have to pass alpha value less than the possible
score, else PV will not get updated (Note: PV gets updated only
for nodes where score > alpha.). So we pass -score+1
Am I right ?
regds
tomar
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