Author: Amir Ban
Date: 14:29:22 01/15/98
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On January 15, 1998 at 07:24:55, Ernst A. Heinz wrote: >On January 15, 1998 at 07:19:48, Amir Ban wrote: > >> >>Often when you evaluate a node, you have a situation where you can >>record a bigger depth in the hash entry, but the eval info is less >>exact. What do you do in this case ? >> >>As an example, suppose your best move was e4 up to ply 6 with value >>+0.10, and then at ply 6 you find d4 is better. At ply 7 d4 is still >>best with value +0.20. When you evaluate e4 at ply 7, you have the >>choice of updating e4 to 7/LE 0.20 or leave it as 6/EQ 0.10. There are >>advantages and disadvantages either way. >> >>Amir > >Proven standard is depth having higher priority than bound type. >Many experiments of different researchers agree on this. > >It also holds for "DarkThought". > >=Ernst= I know this is the standard, and I have been doing it myself. Lately I deviated from this and I am pleased with the results so far. Here's a scenario that may show why depth-priority might do more harm than good: Suppose you do a windowed search, and it fails high. Many of the nodes in the subtree now have a hash entry which says GE beta. You are now going to open the window and redo the search, probably visiting all these nodes again at the same depth, but with a different alpha-beta window. If you think about it, all your hash info is useless because your new alpha-beta window already says it. Now, you could be gathering new and useful hash info at lower depths, but you are not recording because of your depth-priority, so you are stuck with the useless data. Amir
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