Author: Robert Hyatt
Date: 18:33:23 02/21/00
Go up one level in this thread
On February 21, 2000 at 21:03:19, Christophe Theron wrote: >On February 21, 2000 at 16:52:03, Robert Hyatt wrote: > >>On February 21, 2000 at 13:33:58, Christophe Theron wrote: >> >>>On February 21, 2000 at 12:16:49, Tom Kerrigan wrote: >>> >>>>On February 21, 2000 at 11:37:52, Mark Taylor wrote: >>>> >>>>>An idea I had was to have a small incrmental value subtracted from the eval, >>>>>this small increment getting larger the deeper into the tree search the eval was >>>>>returned from. I had already done this for the values WON & LOST, but I >>>> >>>>This is a good idea. However, most chess programs have transposition tables. The >>>>ideas are not compatible, because ttables assume that a position's score is >>>>constant. You will probably want to have ttables instead of your penalty, >>>>because once in a while there are huge benefits to having a ttable. >>>> >>>>>What I did in the end I made the first search iteration look at positional eval >>>>>& material eval, then subsequent iterations looked at material eval only - but >>>>>this was really a cop out. >>>> >>>>Yeah, I think this just confuses things. A long time ago I think there was a >>>>program that ran on two CPUs. One CPU ran the regular evaluation function and >>>>one was material-only. They checked each other. But programs these days get >>>>along fine without material-only eval. >>>> >>>>-Tom >>> >>> >>>The very old program Tech (I think the author was Gillogly, correct my spelling >>>please, it was back in 1960) did this, but on only one processor I think. >>> >>>It played rather well, but was seriously handicaped by lack of deep positional >>>understanding. >>> >>> >>> Christophe >> >> >>No. Tech was a 1970+ program. > > >In the book "Echecs & Mips" written by Frédéric Louguet I have found: "1960: >Creation of the Tech program, first program able to compute complicated tactical >positions". > >I remember from articles written by David Levy that Tech used a deep tactical >search (whetever deep meant at that time), but that positional evaluation was >applied to the root moves only. > >I think this approach could be used by beginners in chess programming. The >program could be surprisingly strong (compared to beginner's usual programs). > > > Christophe that is correct. I thought you were talking about using two processors, one for the tactical search and one for the normal search (ie like Sun Phoenix did). Tech was all about being fast, at the expense of making gross positional errors deep in the search (if you can call 3-4-5 plies 'deep'. :) > > > >> The program that did two searches was called >>"Phoenix" by Jonathan Schaeffer. He ran a normal search with several >>workstations in parallel, and a "minix" search using several more workstations >>in parallel. Minix searched deeper looking only for tactical refutations of >>the moves being considered by the normal search. >> >>Tech was a very fast, very "dumb" type technology approach, which is where >>its name came from (tech). Jim occasionally posts on r.g.c.c and can be >>reached there.
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