Author: Vincent Diepeveen
Date: 17:26:51 01/03/06
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On January 03, 2006 at 12:18:58, Tord Romstad wrote: >On January 03, 2006 at 11:49:05, Robert Allgeuer wrote: > >>On January 03, 2006 at 10:49:54, Maurizio Monge wrote: >> >>>What you said is surely true. >>>But what i find strange is that, IIRC, the only quite new technic in computer >>>chess that can be found in fruit is history pruning, everything else is just a >> >>History pruning was already in use in SmarThink and other engines before as >>well. If I am not completely mistaken history pruning was invented by Sergej for >>SmarThink. > >It is possible that Sergei introduced the name "history pruning", but the >technique itself is very old; certainly much older than SmarThink. I no >longer remember where or when I heard about it for the first time, but it was >definitely not in this millennium. >"History pruning" is a really bad name for the technique, by the way. Since >a long time, I have been advocating to rename it to "late move reductions". Ed Schroder earns that credit probably. Somewhere in 80s. See his homepage. Basically not a single concept that has been described past 30 years and which works great nowadays, has been invented by that person in question. Chrilly Donninger described nullmove in 1991 or something, but the technique existed already in the 80s in commercial programs. Frans Morsch was the first to use it recursively in Fritz. Frans really needs some credits there. He *openly* told fritz was using this and how. It was the first time a new enhancement was given free within not too long after invention. Attacktables were used 1988 or so by gnuchess. They were not new. Start of 80s someone in a commercial eprom already had them. Extensions, even older than that. Usually at a certain point, so many programmers have debugged what giants before them invented, that then it leaks out to the scientific world who is doing a publishment. Right now it seems the scientific world is running behind bigtime on the internet and the internet is running behind years on what is in programs. There is at least a 30 tricks which i'm using in diep where i hear no one about. And please realize, diep has a very pathetic search when compared to certain other engines. The basic concepts are nullmove R=3, transposition tables and worlds biggest evaluation function. Vincent >The word "history" is misleading because the technique can be implemented >without using history counters. I currently use a combination of null move >threat detection and evaluation data to make my late move reduction decisions, >and don't use history counters at all. This seems to work clearly better, >at least in my program. > >The word "pruning" is misleading because most people don't use the idea >to prune moves, but only to reduce the search depth. > >"Late move reductions" is a much more appropriate name, and does a better >job of explaining what the idea is about: Reducing the depth for the less >interesting moves late in the move list. > >Tord
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