Author: Tord Romstad
Date: 11:40:37 01/27/04
Go up one level in this thread
On January 26, 2004 at 17:14:34, Dann Corbit wrote:
> /* ----------==== INTERNAL ITERATIVE DEEPENING ====----------- */
>
> /* If we're not doing a NULL move and we don't have a hash move and we're
> * at least 3 ply away from the quiescence search, then try to get a good
> * guess for the best move by doing a shallower search from here. */
> if (depth >= 3 && !do_null) {
> w = search(on_move, ply, depth-2, alpha, beta, do_null, 1);
> /* Re-search properly if the previous search failed low, so that we
> * know we're getting a good move, not just the move with the highest
> * upper bound (which is essentially random and depends on the search
> * order.) */
> if (w <= alpha)
> w = search(on_move, ply, depth-2, -32500, alpha+1, do_null, 1);
> }
Hi Dann,
Are you sure it is a good idea to re-search if the first IID search
fails low? I have never tried this myself, but at first sight it
doesn't look like a good idea to me. When the reduced-depth search
fails low, it is likely that the full-depth search will also fail low.
At fail low nodes, move ordering doesn't matter much, because you have
to search all moves anyway.
Tord
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