Author: Robert Hyatt
Date: 07:43:30 01/20/01
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On January 20, 2001 at 10:10:30, Dieter Buerssner wrote: >On January 20, 2001 at 00:10:45, Robert Hyatt wrote: > >>Two things. 1. You have to correct mate scores to be relative to the current >>ply when you store them. 2. You only do this if you are storing an EXACT score. >>I once had a _horrible_ bug because I was also adjusting bounds (which can be >>mate scores at times) and adjusting the bounds will play hell with the search >>for mates.. :) > >I cannot see, why adjusting lower bound or upper bound scores is wrong. >If you have a lower bound score, that says, that this is a mate to 10 or better >from the root position, and you are 2 plies down in the search, this means, >that the score is a mate in 9 or better from this position. If you later >hit the same position 4 plies down from the root position, you know, that >this line yields a mate in 11 or better from the root. > >I must be missing something ... > >Dieter If the lower bound is mate in 30, and you correct this to mate in 20 because you are at ply=20, you just changed the bound, which is wrong. Just as arbitrarily changing _any_ bound will result in alpha/beta behaving bizarrely. Best advice is to say "try it, you won't like it." I debugged this for a month before I finally figured it out.
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