Author: Robert Hyatt
Date: 21:41:51 02/22/03
Go up one level in this thread
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
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.