Author: chandler yergin
Date: 19:02:16 10/11/05
Go up one level in this thread
On October 11, 2005 at 21:56:32, Dann Corbit wrote: >On October 11, 2005 at 21:53:24, chandler yergin wrote: > >>On October 11, 2005 at 21:34:44, Dann Corbit wrote: >> >>>On October 11, 2005 at 21:10:59, chandler yergin wrote: >>> >>>>On October 11, 2005 at 20:58:29, Dann Corbit wrote: >>>> >>>>>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. >>>> >>>>If I didn't understand it, I wouldn't have posted it. >>>>To have a meaningful dialog about anything, both parties should have the >>>>same consensus about the meaning. >>>>I Posted my meaning; was looking for constructive comments by those that had a >>>>different view. I sure got them.. but instead of commenting on specifics, >>>>they were just personal attacks, with nothing constructive, >>>>I appreciate your review! Please add where you believe I err. >>>>Thanks and sincere Best Wishes, >>>>Chan >>> >>>You err in thinking that chess programs use mini/max to search. >> >>Chessbase does! Ask them. > >If they swear on a stack of Bibles that they use mini/max, I have already >PROOVED that they are lying. But I know they would not say anything so utterly >ridiculous. > >>> They use a more >> >>You say 'they' without being specific. > >I mean each and every chess engine that they distribute does not use mini/max. > >>>sophisticated variant called alpha/beta which cuts the branching factor from 20 >>>to around 6. Then they trim that further with lots of speculation that >>>typically results in a branching factor of under 3. Notice that this does not >>>mean that it seaches half as many nodes, but that in a 17 ply search it is >>>searching less than one trillionth as many nodes as it would with a full width >>>search. >>> >>>You err in thinking that a ply is the same as fullmove. A ply is 1/2 of a full >>>move and constitues one turn for a player of a given color. >> >>You err.. as many have before. >>My Quote: >>"Yes I understand the common terminology of Ply. >>That's why I was careful & precise to note that "for analysis purposes" >>Chessbase considers 1 ply(= half moves, i.e. one move for each side) and >>evaluates every legal move in a position 1/2 ply at a time, which is 1 >>iteration." > >Right. That's utterly wrong. Chess engines search a ply at a time and not 1/2 >ply at at time. Semantics...Chessbase considers 1 ply(= half moves, i.e. one move for each side) Of course the Program searches after every move. 1. e4 Search 1. ...e5 Search Please lets not get hung up on semantics. > >>> >>>You err in thinking that professional chess programs examine every node during a >>>search. No I don't >> >> They search a microscopic fraction of the total number of nodes. >> >>Of course! >> Take >>>a bathtub full of water. Now take an eyedropper and get some of the water. >>>Squeeze gently to eek out the smallest drop you can create. On a 17 ply search >>>the ratio between nodes examined and nodes ignored is less than the ratio of >>>water in the bathtub to that drop you just made. >>> >>>>>>>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)? >> >>I did not compute anything, I was quoting from an example given in the Manual. >>It was an Example they used to illustrate. > >That word you keep using. I don't think it means what you think it means. > >>>>>> >>>>>>That was Dann, not me.. >>>>>>> >>>>>>>Michael
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