Author: Dann Corbit
Date: 17:58:29 10/11/05
Go up one level in this thread
On October 11, 2005 at 20:47:54, chandler yergin wrote: >On October 11, 2005 at 20:34:28, Michael Yee wrote: > >>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). > >No Michael, and as Shakespeare said.. "Aye, there lies the rub.." >Please re-read my Post carefully. >Well.. here.. >"Start your Engine for a position or at any part of a game. >Look at the analysis window >What do you see? >The analysis module should show the following: >The name of the Engine >The search depth (brute force selective) Example "12/40" means that all >variations were >searched to a depth of 12 ply, while some promising continuations were checked >down to 40 ply. >Next should show the move currently being investigated. Example f4-d6 (3/47) >meaning number 3 of 47 legal moves in the position. >Next it will show the speed at which the program is running. >Example: 403kN/s means it is looking at 403,000 nodes (= positions) per second. >This is normal on a 400MHz processor. >The main variation for example shows "=(0.00)", then the best sequence of moves >the program has found so far, the amount of time it has spent computing on the >position,(1 min. 46 sec) and the number of positions it has examined >(41937kN =41,973,000) >The evaluation expressed in units of a pawn, always from the point of view of >White >"+0.53) means the program thinks White has an advantage of about half a pawn; >" (-3.52" indicates Black is more than a piece up. If Mate is found the Program >stops calculating and displays the Mate. (Mate in 6)." > >What if anything is incorrect in the above? There is nothing wrong in the statements above. The problem is in your failure to understand what they mean. >>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)? > >That was Dann, not me.. >> >>Michael
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