Author: Jeremiah Penery
Date: 06:13:15 12/01/99
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On December 01, 1999 at 09:02:29, Jeremiah Penery wrote: >On December 01, 1999 at 07:50:34, Inmann Werner wrote: >>and the hash entry is only used for stopping the search, >>if the found value is lower than alpha. > >But at a fail-high, EVERY MOVE for the next ply failed low - they will ALL be >less than alpha. I thought more about this. :) When this happens some random place in the tree, it probably isn't too bad. You may not have to ever re-search these positions, because they're pointless branches. The place where it really hurts is when you get a fail-high at the root, because that means you have to research everything from depth=2 and beyond, since all the ply 2 moves failed low. This will definitely affect the PV, and the speed. Previously, did you store a hash entry for each position for ply 2 moves, since they all failed low, or did you just put a random move in and mark it fail-low? I'm a bit confused - You didn't use the fail-low for move-ordering in the hash table, but isn't the first thing you do for move ordering to probe the hash table? You will find that this node is a fail-low node, and then you will search the other nodes first, or...? I'm thinking that it was somehow affecting move ordering, even if it was unintended.
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