Author: Robert Hyatt
Date: 20:33:45 02/22/00
Go up one level in this thread
On February 22, 2000 at 13:09:03, Christophe Theron wrote: >On February 22, 2000 at 09:35:22, Robert Hyatt wrote: > >>On February 21, 2000 at 21:46:09, Christophe Theron wrote: >> >>>On February 21, 2000 at 21:33:23, Robert Hyatt wrote: >>> >>>>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). >>> >>> >>>No actually I missed the point in Tom's post. I did not know about Phoenix. >>> >>> >>> >>> >>>>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'. :) >>> >>> >>>Do you remember if he was doing a QSearch, or just used a SEE to terminate the >>>search? >>> >>> >>> Christophe >> >>No I don't, but Jim and I have corresponded regularly over the past 30 years, >>and I don't mind asking. What would be fun would be to see if he still has >>source code... :) >> >>Just to see how it would play on state-of-the-art hardware. > > >Yes, that would be great. But I thought his search was limited to 4 plies or so. > >Anyway, a PC version of this program would be a must for many collectors. > >As would be a version of Machack, or even a version of the IBM704 chess program. > >I don't understand this passion for old chess programs/hardware, but I admit I >love them too. I'm still delighted with ChessGenius for the Palm, which after >all is only a version of the Mephisto Roma (1987) running on slower hardware... >But I like to see it doing tactical blunders from time to time. It looks so >"human like"... And plays very well overall. > >Fernando would love it too. > I used to have the source for mac hack. But it was in PDP 10 assembly language, which renders it useless today of course. :) I'll certainly ask Jim about Tech/Tech II to see if it still exists somewhere. > > Christophe > > > > >>>>>> 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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