Author: Dave Gomboc
Date: 09:02:25 09/21/99
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On September 21, 1999 at 09:40:01, Robert Hyatt wrote: >First the precise formula: > >nodes=w^(floor D/2) + w^(ceil D/2) > >floor=round down, ceil=round up. For d even, this turns into > >nodes=2 * w ^ (d/2) > >for simplicity we generally drop the 2 and just say nodes=sqrt(w^d) > >With that out of the way, that is based on perfect move ordering. As move >ordering gets worse, nodes approaches w^d (pure minimax) which is why we spend >so much time on hash moves, killer moves, history moves, ordering the captures >in order of expected gain, etc. The more accurate the move ordering, the >closer we get to the true alpha/beta node count. As ordering becomes less >accurate, we drift toward the minimax node count. It may also be interesting to note that using completely random move ordering will visit w^(2d/3) nodes (IIRC!) Dave
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