Author: Robert Hyatt
Date: 07:42:25 05/16/03
Go up one level in this thread
On May 15, 2003 at 21:47:20, Jon Dart wrote: >Ernst Heinz did this by using standard test suites, for example Win at Chess, or >ECM (Encyclopedia of Chess Middlegames). He found that the solve rate didn't >really change much with forward pruning on, but the number of nodes searched for >a fixed ply depth decreased 20-50% (this is from the chapter on AEL pruning in >his book Scaleable Search in Computer Chess). He also used other testing >methods, including game play, as detailed in the book. I don't think this methodology is reasonable. For example, suppose your forward-pruning speeds you up by a factor of four. Comparing same-search-depth runs means the FP version will move in 1/4th the time of the non-FP version. Suppose the FP version does worse on three positions? But if you run it for 4x longer, so that it has the same time limit as the non-FP version, the three positions are now "back to normal"??? I think the _right_ way to test is with a fixed time limit so that a version that can go deeper will go deeper. After all, that is the _purpose_ of FP in the first place... > >--Jon > >On May 15, 2003 at 18:17:09, Russell Reagan wrote: > >>I would like to know how to test whether or not a forward pruning method is >>reliable. >> >>I have one idea to test when and if a method is reliable, and I'd like to know >>if it's a good idea or not, and also what other methods might be used to test >>the reliability of forward pruning methods. >> >>My idea requires a collection of games, and two versions of a program. One >>version would have forward pruning turned off, and the other would have it >>turned on. You would feed each version of the program the same game, and let >>each do a search on the initial position to the same fixed depth. If both >>versions report the same move and score, and the version using forward pruning >>had a lower time to depth, then the forward pruning is reliable (so far). If the >>version using forward pruning reported different results, then the forward >>pruning method is not reliable for this type of position. You make the next move >>in the game, and repeat the search and compare the results for each position in >>the game. Then you repeat the process for each game. >> >>When I think about testing the reliability of null-move using this method, I >>think the test would do well. I would expect the test to tell us that in most >>positions, null-move is reliable, and I would expect it to fail for some endgame >>positions, and so this test would tell us that null-move was good forward >>pruning, but to turn it off in the endgame (or detect zugzwang, or however you >>choose to guard against it). I haven't had time to test this though, since I >>just thought of it and I'm not at home. >> >>I am basing all of this on the assumption that the strength forward pruning >>provides is not that it finds better moves at the same depth, but that it >>finishes searching a particular depth in a shorter amount of time, allowing the >>search to go deeper, which is where the added strength comes from. Is this >>correct? >> >>Comments, please...
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.