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Subject: Re: "ALL node" definition

Author: Robert Hyatt

Date: 21:41:51 02/22/03

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On February 22, 2003 at 16:44:10, Dezhi Zhao 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...
>
>Dr. Hyatt,
>
>I am considering the case with transpostion table. At ALL node, is move ordering
>still irrelevant with tree size or search time? I think move ordering could
>still play a role here. Imagine you start with move_a that leads to a new
>poistion and forces many replacements. Later you search move_b whose subtree
>position entry was just overwriten. If you had started with move_b, you could
>have returend immeadiately with a hit.


That is what ETC is about.  I have tried it and found it didn't work for me.
It made the tree smaller, but it made the search slower so it was essentially
a "wash".  Which means, for Crafty, that ordering at ALL nodes is irrelevant
since I don't do anything with ordering there now beyond what I had already
mentioned...

>
>In this case, moves could be sorted by transpostion hits or other criteria to
>maximize utilization of transpostion table, instead of possibility of cut-off.
>Has anybody spent some effort on this?

Again, search for ETC.  that is exactly what it is...

>
>dzhao



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