Author: Robert Hyatt
Date: 16:39:43 06/22/05
Go up one level in this thread
On June 22, 2005 at 17:15:13, Bo Persson wrote: >On June 22, 2005 at 10:01:12, Vincent Diepeveen wrote: > >>On June 21, 2005 at 16:11:50, Bo Persson wrote: >> >>>On June 20, 2005 at 08:06:08, Vincent Diepeveen wrote: >>> >>>> >>>>If at 13 ply the score of other moves is 0.35 or so and from this root move it's >>>>0.400, then we have a 100 point difference between 0.300 and 0.400. >>>> >>>>Now we need possibly a 100 researches to get to 0.400, but at least 2 dozen or >>>>so. As we will use bounds 0.300 0.301 0.302 0.303 0.304, hoping that the score >>>>is close to 0.300 of iteration 12 of course. >>>> >>>>PVS is far superior in this as we can determine the true bound directly by >>>>taking the tree of 12 ply search depth. We add 1 ply to it and we already have a >>>>root score of real close to 0.400 to it. So for the price of a node or 50 using >>>>hashtables we directly determine a true bound or somethign real close to the >>>>true bound, where MTD needs 20+ researches for. >>>> >>>>Is my point clear now? >>> >>>This is the usual Vincent thing - he can't get it to work, so it just doesn't >>>work. >>> >>>Who said you had to add 1 millipawn for each research? You can accellerate the >>>step (+16, +32, +64, etc), until you step over the target, and then zoom in >>>again. >>> >>>To go from 0.300 to 0.400, my program tries this series: >>> >>>0.300 0.316 0.348 0.412 (fail low!) 0.380 0.396 0.404 0.400 >>> >>>That's eight (8) searches, not 100, not even 20+ ! >> >>>Bo Persson >> >>By not using step 1 initially you remove all advantages that MTD *might* offer. > >No. > >If the final score would actually be 0.301, I would go > >0.300 0.316 0.308 0.304 0.302 0.301 > >That's 6 null window searches. Not bad. > >Of course, if the new score just happened to be 0.316, I would find it really >fast! > >Why optimize for the 0.300 -> 0.301 case? Is that very frequent in your program? > > >Bo Persson This is a hopeless argument of course. The main problem I had in fooling with this was "lazy eval" caused way too many problems. Don D. suggested a fix that seemed reasonable later, but you don't want to let lazy eval trick you into failing the wrong direction just because the eval says <X or >Y and returning a bound that is too far off...
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