Author: Robert Hyatt
Date: 13:40:12 02/02/00
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On February 02, 2000 at 14:39:18, Pete R. wrote: >I ran both Fritz 5.32 and Crafty 17.7 to 16 ply, and while they agree that Bg5 >is best they do not eval a clear win until you feed it to them. If you give >them 1. Bg5 Nc5, Crafty finds the Bxd8 Nxa4 O-O-O +- continuation before Fritz >does. But neither one of them sees this from the root position. This is yet >another example of a position where the search depth is sufficient to cover the >solution, but the programs don't see it until you give them a hint. >Specifically the position after 1. Bg5 Nc5 takes 12 ply for both Crafty and >Fritz to see the win, but since I ran them both to 16 ply, they should have seen >the win from 2-ply back, but didn't. Of the programs I have, Hiarcs 7.32 is >fastest to see the win (and eval it as such) in the position after Bg5 Nc5, but >is as blind as the others to see this winning line from the root. > >In theory alpha-beta should cover this, i.e. a 16 ply search should find >something that a 12 ply search finds from a position 2 ply down the road, but >reality is different. This is another example where a bunch of shorter searches >backsolved would be superior to a deep search from the root. One possiblility is that Nc5 is not the best reply to Bg5? That will make this behave as you explain.
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