Author: Robert Hyatt
Date: 08:29:07 02/14/03
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On February 14, 2003 at 04:58:35, Peter McKenzie wrote: >On February 13, 2003 at 23:58:10, Robert Hyatt wrote: > >>On February 13, 2003 at 15:23:15, Peter McKenzie wrote: >> >>>Just wondering how many programs are using the Enhanced Tranposition Cutoffs >>>algorithm, or if people have tried it and had trouble with it. I think I'll >>>have a go at implementing it shortly. >> >>I tried it several years ago with no success. IE the cost was a wash with >>the reduced tree size, but that was all. I had to write a special "Make()" >>function that did nothing but update the hash signature so that I could >>probe to see if the new position would produce a quick cutoff. Since there >>was no gain (and no loss) I stopped using it. > >Where in the tree were you applying ETC? I tried several limiting approaches. The first attempt was to probe everywhere, but since I don't hash in the q-search I obviously didn't do anything there. I then modified it to not probe within N plies of the q-search, where N could be changed. However, no matter what I did, I couldn't get the cost of the hash probes to do more than break even with the savings in tree size, so I gave up. Note that this was quite a while ago, as in maybe 5 years ago, so it might well produce a different result today... although I doubt it based on the old results. > >> >>YMMV of course, and checker programs seem to report good results using this, >>but their tree is a different shape. >> ><snip>
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