Author: Dann Corbit
Date: 18:56:32 10/11/05
Go up one level in this thread
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. >> >>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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