Author: KarinsDad
Date: 06:46:52 01/19/99
Go up one level in this thread
On January 19, 1999 at 08:17:30, Robert Hyatt wrote: >On January 19, 1999 at 01:57:31, KarinsDad wrote: > >>On January 18, 1999 at 18:53:02, Robert Hyatt wrote: >> >>[snip] >> >>>This is a classic question that can be answered experimentally. There is no >>>'holy grail' for all programs. The iteration-to-iteration swings can cause each >>>program to have different. >> >>Robert, >> >>What is iteration to iteration swings? Is this when you search one more ply >>deeper? >> >>Isn't the difference in "optimal" alpha beta window between programs due to >>their evaluation function? Or am I missing something? Is there any other >>components (within a program) which would give varying results in an optimal >>alpha beta window between programs? > >think about the value of a 'tempi'. Most good chess books would say that >3 tempi are worth about a pawn (hence why gambits work). Which means that if >you search one ply deeper, the side getting the extra move should see some sort >of advantage to the extra move he gets. So for an N ply search, you could see >scores like this: ply=1 +30, ply=2, 0, ply=3, +35, ply=4, +5, etc... > Ok, so this explains what iterative swing is (makes sense). It also seems to imply that my conjecture about an optimal alpha beta window being based on a given evaluation function is correct (although you didn't really answer that question). If that is correct, then it would seem to me that it implies that a given alpha beta window would work fine for certain types of positions, but that for different types of positions, you would get more fail lows / fail highs for the same evaluator and that you would have to do more re-searches. Is this correct? KarinsDad > > > >> >>Thanks :) >> >>KarinsDad >> >>> >>>Try it with different windows, over a large test of positions, and just pick the >>>window that works best (produces the fastest time-to-depth.) One trick.. watch >>>your odd/even score swings (if you have them). And if you see them in your >>>program, anticipate by correcting the window so that the odd/even swings don't >>>take you over the edge too frequently...
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