Author: Vincent Diepeveen
Date: 15:52:57 08/10/00
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Christophe, a pawn is 1000 centipawns in DIEP. Every new ply diep usually has a new score as it is using a lot of knowledge in its evaluation. If your evaluation is every iteration nearly the same, i can imagine MTD works, like the original implementations in cilkchess using an evaluation which is always material based, +0.60 means the position is incredible lost for you usual. If your scores keep jumping up and down, then MTD is a very bad algorithm, especially using 1000 centipawns with a score jump of normally quite much, we talk about a huge number of researches. No program can afford MTD then. Apart from that MTD causes another obvious things: it's bad for move ordering, and the predicted move in an MTD program usually is gonna lose time during pondering for you, as it fills hashtables with crap. On August 09, 2000 at 16:01:49, Christophe Theron wrote: >On August 09, 2000 at 05:41:22, Andrew Williams wrote: > >>On August 08, 2000 at 15:56:04, Christophe Theron wrote: >> >>>On August 06, 2000 at 16:36:15, Vincent Diepeveen wrote: >>> >>>>Show me an MTD program that uses less nodes a ply as DIEP does. >>>> >>>>What diep is doing is very simple in search: >>>> >>>> PVS (starting with -infinite) >>>> check extensions >>>> checks in qsearch >>>> nullmove R=3 >>>> no other crap. no pruning. Perhaps at WMCC i prune a bit, >>>> but that's because against computers playing is different. >>>> >>>> Yet i'm missing programs using less nodes a ply with MTD. >>>> I"m missing *any* deep searching program that uses MTD actually. >>> >>> >>>Anmon, a french chess program, uses MTD(f). It is a strong program. >>> >>>If you are not pruning in the tree, then MTD(f) should be better for you. I >>>don't use MTD(f) because I use the value of alpha and beta to prune in the tree, >>>and with MTD(f) this kind of pruning makes the search really unstable (you get a >>>fail-high, and when you re-search with a higher window you get a fail-low, >>>oops). >>> >>> >>> >>> Christophe >> >> >>What you can do in these cases is to use the external bounds instead of >>alpha and beta. By "external bounds" I mean the bounds that have been >>established in the mtdf() loop which is driving the alphab-beta search. >> >>Cheers >> >>Andrew > > >Thanks for the idea. > > > Christophe
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