Author: Dave Gomboc
Date: 13:41:17 03/28/00
Go up one level in this thread
On March 28, 2000 at 13:27:59, Andrew Dados wrote: >On March 28, 2000 at 13:14:59, Dave Gomboc wrote: > >>On March 28, 2000 at 12:17:14, Tom Kerrigan wrote: >> >>>On March 28, 2000 at 11:08:59, Bas Hamstra wrote: >>> >>>>Question is: is move ordering very important near the root and less important >>>>near the leafs? Bob Hyatt says so. One mistake near the root costs millions of >>>>nodes. On the other hand almost all nodes are leafnodes, so bad ordering near >>>>the leafs costs millions of nodes too. >>> >>>I think so. At least in my program, hash table size does not matter much. (See >>>previous posts in this thread.) >>> >>>>Has anyone measured if you search somewhat deeper if you do extensive ordering >>>>near the root and cheap (just MVV/LVA) ordering near the leafs and in the >>>>qsearch? >>> >>>Because SEE only improves things by ~%10 over MVV/LVA, I don't think doing SEE >>>at the root and MVV/LVA otherwise would make much sense. You can do searches to >>>improve move ordering, which is the idea behind internal interative deepening. >>>So yes, people are doing this, and I believe it works, although I haven't tried >>>it myself. >>> >>>-Tom >> >>I have yet to figure out why people who use iterative deepening and understand >>why it works do not also use internal iterative deepening. Could somebody >>enlighten me? >> >>Dave > >It will only work when node you do it at will fail high, otherwise it's waste of >nodes... so eg Bob does it along PV and only when no good move from HT... Some >programs have 'double null move', which accomplishes pretty much the same. > >-Andrew- (I wasn't suggesting to use it everywhere.) I don't understand how double null-move accomplishes pretty much the same (no doubt because I'm not exactly sure what you mean by "double null move" ;-). Let's say you have depth 7 left to go, and you see that don't have a good move from the hash table. IID will pick a move using searches of depths 1-7... and the searches at low depths are no more wasted than they are with normal iterative deepening. What will "double null move" do in this circumstance? Dave
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