Author: Dann Corbit
Date: 19:54:03 01/13/01
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On January 13, 2001 at 21:44:45, Howard Exner wrote: >Here are some results by Tiger 13 and Century 3on an Athlon 900. > >Tiger 13 avoids Qe4 at 3:03 by choosing Ka6 at depth 13. >Later on the same ply it changes to b3 at 4:27 then b4 at 7:21. > >Century 3 has this output > >0:52 12th ply Qe4 +1.66 >2:18 13th ply Qe4 -1.29 > >Will not avoid the move Qe4 till the next >iteration in 14:22, playing b4. > >That seems like quite a long delay as the eval swung +2.95. >Given that Qe4 had -1.29 after 2:18 when it took an extra 12:04 >to resolve that b4 is better, why such a long delay? It's called fail low, followed by massive fail high. The program has to research the entire tree. A particularly bad combination. ;-) I am sure that it would play the correct move as soon as the fail high occurs, if the time ran out. It just might have a faulty evaluation of the true value if it has to move early. That would get corrected on later plies. On crafty, for instance, when the fail high occurs, you will see ++ <new move> but no score and it will just keep pounding until the time runs out or until it resolves the score correctly. When that happens, it has already found a move and knows that the move is better, but it does not know how much better or if there is an even better alternative [which is pretty rare after a fail high but definitely does happen].
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