Author: scott farrell
Date: 01:28:08 05/18/03
Go up one level in this thread
On May 16, 2003 at 10:42:25, Robert Hyatt wrote: >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... maybe you can run the non-fp version, and time how long it takes to find the solution. Rhen allow a maximum time control for the fp version equal to the solve time - if it solves in less, success, if it doesnt solve in time = failure. Scott > > > > >> >>--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...
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