Author: Robert Hyatt
Date: 07:08:04 03/22/00
Go up one level in this thread
On March 22, 2000 at 06:30:58, Jan Pernicka wrote: > Hi, >I think that quality of chess program depends strongly on "well-tuned" >extensions,i.e. to let the program to search deeper (e.g. 1 ply) after >special kinds of moves - > - example: While searching, I have 1 ply to horizon, so normally >after the next move the quiescence search will start( i will reach the horizon). >But when the move is, say, check I will add 1 more ply. So check is the >special kind of move in this case that causes extension (=adds 1 ply) > > Several questions arise: > 1) what kind of extensions(=EX) to use? > this is commonly known - checks, recaptures .... > you can surely develop many other criteria - especially after > watching a kind of "Tal-like" game :) , but: > 2) where (and when) to use extensions? > this is much more interesting question, because EX when don't used > carefully explodes the tree...., so you can't use EX carelessly > (i.e. not like rule: IF it's check THEN add 1 ply). I do just what you suggest can't be done. If I am in check at any ply in the tree, I extend by one ply, period. I qualify recapture extensions quite carefully so they don't get triggered, and I also use fractional extensions so that they don't explode too badly... (IE if one side is both in check _and_ only has one legal move to get out of check, I extend by 1.75 plies. > > (*)The CRUCIAL question is - how to reduce the amount of EX that are possible > to use ( to complete search in reasonable time)? This depends NOT > on the kinds of EX but more on situations (positions) WHERE they are > used. > > My opinion is that this could safely be used in the way: > - allow not more than 1 (or 2...) extensions in every branch > of the game tree > - but seem to me like "nothing special"... > > Do you know about some more sophisticated ways of solving this problem > (i.e. problem (*) ) or will there still be the equality: > strong chess program = fast chess program ? > > My opinion is that programs that only use exhaustive search (+ quescence > and a bit of EX as a spicery...) can only thanks to guys from Intel(C) > that they are better and better and, what is more important, they can't > develop too much... > - that means - given a depth d - to develop and then still refining a > program that searches just at the depth d (+ quesc...) (or more strictly: > - to choose a move if you are allowed to use not more then > N computer instructions (or ticks of processor!)...) can't produce > much better program than we started with... > > This seems that I tend to "return" to programs such as Shannon B types, > but it's not true. What I want is to refine exhaustive-searching > programs in the way I've just written. > > Another (and last...) question connected with this is: > When coputer beats computer - what are the common reasons > of that loss? > I think it could be: > 1) loss of piece in the middle of the game > 2) still more and more positional advantage during the game > 3) blunder in endgame > 4) wrong transition from middle game to endgame > 5) others > If you are more experienced, you could enrich/modify this list managed > by your opinion... > It would be also nice and MUCH MORE interesting to estimate the frequency > of results of the 1:0 (or 0:1) games (e.g: "point 1) - 10% of winning > games") > > Well, thank you for your patience and thank you in advance for your > suggestions, opinions,comments,critics and reactions at all... > > Jan Pernicka
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