Author: Robert Hyatt
Date: 12:33:00 08/14/05
Go up one level in this thread
On August 14, 2005 at 14:57:50, Brian Richardson wrote: >Just wondering if others see this behavior or not. > >In the position below, Tinker prefers Qc7 after a bit. > >[D]5rk/3b2p/1q1p1p1p/2p1p/1pP1P1P/1P1PQP/r2N2KR/7R/ b 0 1 > >However, in the "flipped" position (horizontally around a rank axis) >it does not like Qc2 (I think the flip is correct) > >[D]7r/R2n2kr/1p1pqp/1Pp1p1p/2P1P/1Q1P1P1P/3B2P/5RK/ w 0 1 > >When I ran this test with Crafty, and flipping, the moves are also a bit >different, as are the scores for each full ply. > >So, I'm wondering if this is an asymmetrical evaluation problem, or search >instability, or no big deal. > >Thanks Here's the thing for crafty. It is 100% symmetrical if you just flip the board along either axis. I test this all the time. But if you do a search, it might not be, because my move generator generates moves in a specific order, and if you flip the board, the move order will change (think about FirstOne() applied to a bitboard that is rotated, you get a different first or last bit set, etc... a 1-ply search should be perfect unless there are two moves with the same score, and flipping the board causes the generator to produce a different order for the two moves in questio... My "rule of thumb" is _everything_ is a big deal, until properly explained...
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