Author: Michael Yee
Date: 17:34:28 10/11/05
Go up one level in this thread
On October 11, 2005 at 19:52:46, chandler yergin wrote: >On October 11, 2005 at 19:43:59, Michael Yee wrote: > >>On October 11, 2005 at 17:46:02, chandler yergin wrote: >> >>>I apologize if I have offended anyone. >>>A case of "Apples & Oranges" again.. >>>Misunderstandings.. >>>Stephen, and a few others here, know I seldom voice "Opinions"; >>>I Post facts.. >>>That way... if someone differs from the Post, they should attack the Fact, >>>not the Poster. >>>It doesn't always work that way... >>>Everything I have Posted about Computer Chess Programs..I gave the Link >>>Everything else I have Posted about Engines, Analysis Modules, is directly >>>from the Chessbase Manual. It therefore refers to the Top Commercial >>>Programs only.. Fritz, & Shredder >>>Many of you that Program your own Engines 'tweak' them as you desire, >>>and have a lot of fun. >>>Players mostly use the Top Commercial Programs to assist in their play >>>and improve their expertise. >>>Thanks to a recent Post by Dan H. some of the confusion has been cleared up. >>>Chessbase does use Mini/Max and so does indeed search every legal move >>>for every position. >>>So the "Apples & Oranges" now are just the difference between the Top >>>Commercial Programs and the others. >>>I find it very intersting that some of the 'lesser' Engines are really >>>kicking Butt! Congrats to all! Keep it up... >>>A Swift Kick only hurts for a little while.. >>>;) >>>Chan >> >> >>The posts from Dan don't say that chessbase uses minimax and searches every >>legal move for every position. > >I know he didn't say it.. I said it! > > In fact, he said something almost the >>opposite--that if a program worked that way, it would be crushed. > >Just plain wrong..sorry. >> >>You actually supplied evidence of the answer in one of your other posts (where >>you provide a description of the analysis output). The analysis window reported: >> >>search depth = 12 (selective depth 40) >>positions searched = 4.2 x 10^7 > >I was using an example.. the type of info the Analysis Module window shows. > >> >>If the analysis module really searched every position up to depth 12 >>(approximately 20 moves, 20 replies to each of those moves, 20 replies to each >>of those replies, etc.), then it would have searched >> >>20^12 = 4.1 x 10^15 positions >> >>This is way more than what was reported in the analysis window. (And the 20 is a >>very low estimate of average moves per position anyway.) Instead, >> >>4.32^12 = 4.22 x 10^7 >> >>shows a branching factor that's more like 4--i.e., the program was not searching >>every move in every position. >> >>Michael > Michael, Please read the Chessbase Manual! >Do you have Chessbase? Do you have Fritz or Shredder? >If so Start the engine look at the Analysis Window as I have requested. >You will find what I said. EVERY Legal move in the position is evaluated. >It's the way it works. Like it or not. Some commercial engines I have include an old fritz 7, shredder 9 uci, fruit 2.2, and gandalf 6. I've analyzed positions before (e.g., during some of the recent World Championship games from Argentina). What I see are depths, selective depths, and node counts that are not consistent with a program that searches every legal move in every position. You're right that engines do look at each move in the root (initial) position (as Dann noted in another post). If that's what you meant, then I agree. But you seem to referring to *all* positions (not just the root). You yourself computed a while ago an estimate of the number of move sequences that can happen from the start position. Given the nodes per second you see in the analysis windows, how could the engine possibly be following all move sequences (even taking into account transpositions)? Michael
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