Author: Vincent Diepeveen
Date: 13:36:15 08/06/00
Go up one level in this thread
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. On August 06, 2000 at 10:31:58, An drew Williams wrote: >On August 06, 2000 at 09:38:18, Vincent Diepeveen wrote: > >>On August 05, 2000 at 11:37:01, Larry Griffiths wrote: >> >>>Which Algorithm is considered the best now-adays. >> >>Depends upon what kind of program you make. >> >>If you have an evaluation function that has patterns which all deliver >>very small penalties and bonusses, from which the summation also adds up >>to a near to material only evaluation, then MTD is an interesting >>alternative. > >PostModernist uses MTD. It would be incorrect to describe its evaluation >as being "near to material-only". This opinion (on MTD) is one that Vincent >has expounded before, without much in the way of supporting evidence. > >> >>If the evaluation function is either big, using a pawn as being >>worth 1000 points instead of 1 point, the eval is huge, or having high scores >>for for example king safety and or passers, >>then you have only 1 option that outperforms >>*anything*, and that's nullwindow search also called principal variation >>search which is pretty easy to implement. >> >>Usually at the start of your program MTD looks interesting, if your >>program gets better (more knowledge in eval, less bugs in search and >>better move ordering), then PVS usually outperforms anything. >> > >I don't think there is any evidence anywhere that supports Vincent's opinion >about MTD. Just stating an opinion does not make it true :-) > >>My advice is to start with PVS and not look to the rest. >> >>>NegaScout? MTD? PVS? Others? I am looking to implement one of the best search >>>type algorithms in my program. I would like to get it into the 2000 rated range >>>as this has been my lifetime goal. Then, maybe install winboard or something so >>>it can compete against other programs to get a rating. >>>I dont like MTD as it seems to be complex. >>> >>>Larry. > >My advice would be to get a straight alpha-beta search working, starting >with bounds of -inf..+inf. This won't be terribly competitive, but you >can use it as a stable reference when you move on to more sophisticated >approaches. When you're happy with your alpha-beta search, try implementing >an aspiration-search, which is like alpha-beta except that you start with >bounds of score-50 .. score+50, where score is the value returned from the >previous iteration. You will need to provide some way of handling the case >where the returned score from *this* search falls outside this "window". >Once you've got your aspiration search working properly, you'll be in a >strong position to decide where you want to go with your program. > >Above all, have fun with your program! > >Andrew Williams
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