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Subject: Re: "ALL node" definition

Author: Robert Hyatt

Date: 18:46:44 02/23/03

Go up one level in this thread

On February 23, 2003 at 10:30:26, Tony Werten wrote:

>On February 21, 2003 at 23:48:52, Robert Hyatt wrote:
>>On February 21, 2003 at 13:26:34, Alvaro Jose Povoa Cardoso wrote:
>>>Could someone please define what "ALL node" is and axplain how do we process
>>>these type of nodes?
>>>Best regards,
>>>Alvaro Cardoso
>>If you look at a perfectly ordered alpha/beta tree, after you search the first
>>branch at a node to establish alpha, you search the rest of the branches, and
>>at each successor you search only one node (the refutation move).  But at the
>>next ply below that you have to search _all_ moves.  This alternates down
>>through the tree.  At "all" nodes, move ordering is totally irrelevant.  At
>>successors to all nodes, you get "cut" nodes where you only need to search one
>>move, if you can search a good move first...
>If you're sure the other moves don't give a cutoff, why bother searching them at
>all ?

I am not sure, as I said.  92% of the time the _first_ move causes a cutoff
if one occurs.  That only leaves 8% for the rest.  What is the probability
that the good captures, the hash move, the killer moves and a few history
moves won't cause a cutoff but a move left over will?  Very low.  But _not_

However, this is what forward pruning ideas are based on, and several programs
are using the idea to good effect, at the risk of overlooking something that
is obscure.  I just haven't elected to take that "jump" yet, but it is on my
list of things to play with.

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