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Subject: Re: Is the crafty approach to pondering the right one?+suggestion

Author: Bruce Moreland

Date: 09:31:44 05/25/00

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On May 24, 2000 at 19:23:16, Roberto Waldteufel wrote:

>My program does precisely what you describe - it ponders by simply searching as
>if it were to play for the oponent. Have you noticed a significant improvement
>by focusing only on the predicted move? My reasoning in adopting this approach
>was that the predicted move would be the root PV move in our method, which takes
>the lion's share of the search time anyway, so the time investment in the other
>moves is only a modest, and some advantage is achieved whatever the oponent
>plays. Maybe I should switch to Crafty's method?

The PV takes most of the time, but you still have to get a ply less.  If you
search for 3 minutes, on position P, you'll get to D plies.  If you choose a
successor of position P and search for three minutes, you'll get to
approximately D plies again.

So what we've really got to choose between here is:

1) Picking the best move and searching to D plies.

  - or -

2) Searching all of them to D-1, then relying on the hash table to have anough
information that we'll get through D plies somewhat faster than we would have
when it comes time to search it.  This is a clearly inferior solution if the
predicted move is made, but you have to balance this against the idea that you
might have some efficiency gain if the opponent makes a move that wouldn't have
been predicted.

I haven't done any experiments but I think the first way must be better.  You
predict a lot of the time, and therefore you receive the full benefit.  You
throw your opponent off with an instantaneous reply in some cases.

Weighed against this some increased efficiency getting to depth D-1.  Maybe it's
better but I doubt it.

bruce



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