Author: Vasik Rajlich
Date: 00:56:09 02/04/06
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On February 04, 2006 at 03:21:12, Bernd Nürnberger wrote: >Hello, > >I have a question concerning the rate of beta cuts. My program prunes the tree >by doing a beta cut at about 5-10% of all nodes. This seems rather low to me. >Thus most moves that were generated are actually made. Nethertheless I am >getting rather low node counts and a mediocre first cut rate: for WAC (pos >1-300) at depth 8, my program searches about 69 M nodes with a first cut rate of >88%. > >Now to the question: is a cut rate of 5..10% common?? I often heard that most >moves generated are nether done because of beta cuts. That's not the case in my >program. >For WAC (depth 8) 88 M nodes are generated and 69 M nodes are done ! > >Configuration: >- Hash Table (1 M entries, deep/new two-level replacement) >- Razoring/(Extended) Futility Pruning >- Null Move (rather aggressive) >- Move Ordering: > x hash move (IID) > x winning + equals caps (by SEE, only x-rays capturer) > x killer 1 / killer 2 > x non-caps (history heuristics) > x losing caps >- PVS / aspiration search >- QS (prunes rather aggresively using SEE) >- plain vanilla eval (mat + pc-sq + boni/penality for castlings) > >Any comments appreciated :-) > >Bernd In a classical search without razoring-type stuff you'll fail high at well over 90% of nodes, and will need much fewer than 69M nodes to do 8 iterations. It's possible you have the alpha-beta logic mixed up. You might want to step through a sample variation move by move. For this the "Chant" tool (advertised here from the search engine page) is quite handy, it's what I use. Vas
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