Author: Robert Hyatt
Date: 19:48:12 10/23/00
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On October 23, 2000 at 20:50:35, Ratko V Tomic wrote: >>>> GT has larger-than-life king safety scores. That >>>> is all. No different search paradigm or anything else. >>... >> Christophe specifically said that the search is the same for both >> programs. I took that as being true,as it seemed to match my >> impression after watching games. It speculates more. But it >> isn't searching _differently_ at all. > > >There is quite a bit of space in between, to paraphrase your earlier comment, >'large safety score and nothing else' and your current one 'is not searching >differently'. The hypothesis I sketched in the previous note is just one of many >conceivable ways in between, where one can say 'the search is the same' (i.e. it >is using the same iterative alpha-beta & support routines), yet the novelty >cannot be said to be merely in a new leaf evaluator (or its weight) but it would >be in a way how the inputs and outputs of the search are interacting across >iterations via pre/post-processors, as well as how much information is >transferred that way (is it just score, hash, history entries & killer moves, as >in most programs, or something extra which helps GT make fewer mistakes in >deciding to undertake apparently open ended king-side attack). > >While Christophe did say the search is the same (and one can parse that to mean >many things; even Botvinnik's program had alpha-beta search in the lower layer), >he also suggested, in response to dismissive comments about the GT style as >being just another king safety tweak, that you're welcome to go ahead and >increase the king-safety scores in Crafty and see how far that gets it. How do you think I arrived at the _present_ king safety scores? Here is the point: if you have a good search (and CT certainly appears to meet that criterion) so that you don't get out-searched very often, then you can be more speculative. If you do get out-searched, then you will have massive problems, as CSTal did in every group of games I watched it play vs Crafty. I'd be willing to bet that I can tune my aggressiveness way up, _and_ play that version using a big alpha machine (to be sure I don't get out-searched anywhere along the way) and the aggressive version would do fine. But as hardware becomes more equal, then the 'speculation' had better be right. Else the more accurate search will find the holes in the speculation and blow through them. We actually played tuned like this in several ACM events using Cray Blitz. And it worked quite well since we were out-searching all the micros by huge margins. But against more equal opponents like deep thought and hitech (and belle in the early 80's) this was not a wise thing to try.
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