Author: Robert Hyatt
Date: 08:59:34 03/09/04
Go up one level in this thread
On March 08, 2004 at 20:12:52, J. Wesley Cleveland wrote: >On March 08, 2004 at 14:20:24, Robert Hyatt wrote: > >>On March 08, 2004 at 13:20:26, J. Wesley Cleveland wrote: >> >>>On March 07, 2004 at 13:47:03, Robert Hyatt wrote: >>> >>>>On March 06, 2004 at 22:20:32, Will Singleton wrote: >>>> >>>>>On March 06, 2004 at 20:45:17, scott farrell wrote: >>>>> >>>>>>On March 06, 2004 at 20:02:13, GeoffW wrote: >>>>>> >>>>>>>Hi Dan >>>>>>> >>>>>>>Thanks for the extensive analysis, that was a lot of output so I summarised the >>>>>>>times to avoid the obvious Bishop takes rook >>>>>>> >>>>>>> >>>>>>>Amy-net-087............00:16 >>>>>>>Aristarch 4.41.........00:02 >>>>>>>DeepSjeng..............00:04 >>>>>>>Delfi-440..............00:13 >>>>>>>Dragon_45..............01:23 >>>>>>>ELChinito 3.25.........00:06 >>>>>>>Glc300.................00:05 >>>>>>>Gothmog................01:31 >>>>>>>Kke-253................00:08 >>>>>>>Ktulu..................00:23 >>>>>>>List512................00:04 >>>>>>>Patzer 3.61.......... >00:35 not resolved >>>>>>>Quark-232-net..........00:53 >>>>>>>Ruffian_202............00:03 >>>>>>>Ruffian_210........... 00:04 >>>>>>>Smarthink-017a.........00:10 >>>>>>>Yace...................01:06 >>>>>>>Shredder 7.04..........00:03 >>>>>>> >>>>>>> >>>>>>>This is seemingly a good test position to separate the elite programs from the >>>>>>>merely good ones, the real top programs can see and resolve this threat in less >>>>>>>than 5 seconds. >>>>>>> >>>>>>>I have only got to improve my program by a factor of 300 to get there, Arrrrrgh >>>>>>>! >>>>>>> >>>>>>>It looks as though my program is the only one that really suffers from a nodes >>>>>>>explosion though. >>>>>> >>>>>>Instead of trying to solve the fail low at depth 12, and cause a node explosion, >>>>>>on the fail low - go back to either depth 11 to reasearch, or depth 1. This way >>>>>>the hash will know that the captures will fail, and start choosing seemingly >>>>>>poorer moves at lower depths, but the fail low will be solved in many less >>>>>>nodes. After seeing the faillow at depth 12, it might solve it using the hash at >>>>>>depth 9. >>>>>> >>>>>>Scott >>>>>> >>>>> >>>>>I do something like that, and I think it can help for some score drops. (I >>>>>don't have fail-lows, I have score drops at the root (pvs, window wide open or >>>>>closed).) Note that the ply changes from 12 to 9 after the bad score, allowing >>>>>a new move selection in a shorter time. >>>>> >>>>>8 191 20 62537 Bxf6 exf6 g6 Bf2 Bc6 Qg4 Qd8 >>>>>9 187 35 115687 Bxf6 gxf6 g6 hxg6 >>>>>10 173 49 169855 Bxf6 gxf6 g6 hxg6 fxg6 Bf2 Qd8 >>>>>11 131 95 334767 Bxf6 gxf6 g6 Qg5 Nd7 hxg6 fxg6 Nxg6 hxg6 Bxg6 Qd8 >>>>>12 -293 646 2281714 Bxf6 gxf6 Ng6 hxg6 fxg6 Nxg6 Bc6 Ne7 Rxe7 Qh4 h5 >>>>>9 -293 646 2281715 Bxf6 >>>>>9 131 765 2698812 b4 >>>>>10 105 890 3143214 b4 Rf3 bxa3 bxa3 Bxa3 h6 g6 Rf1 Bc6 Bf2 >>>>>11 105 1162 4192271 b4 axb4 axb4 Rf4 b3 >>>>>12 99 1968 7109127 b4 axb4 Bxf6 exf6 g6 hxg6 hxg6 bxa5 Rxa5 >>>>>13 106 3434 12510952 b4 axb4 axb4 Rf4 Ra2 Qg2 b3 Bb1 Ra1 Bf2 Nd7 h6 g6 >>>>> >>>>>That's amateur 2.80 on a p4 2.8ghz. >>>>> >>>>>Will >>>> >>>> >>>>here is a technical issue question: >>>> >>>>you fail low on move x. you back up 4 plies. what do you do if move x is >>>>searched first and it fails low instantly??? back up 4 more? repeat? etc? >>>> >>>>I found problems trying this in Crafty a good while back. As in a loop that >>>>won't end until time runs out... >>> >>>I think you misread what he is doing. If he gets the equivalent of a fail low at >>>the root at ply n, he widens the search window and restarts the search at ply >>>n-3(a form of iterative deepening). I tried something similar with Crafty and it >>>helped quite a bit on fail lows. The problem is that after a fail low, the hash >>>table is of little use, esp. with failsoft, and move ordering goes to pot. >> >> >>Perhaps you missed my point here... >> >>If you reduce the depth in Crafty, _how_ do you guarantee that when you back up >>N plies and start the search, you don't get the fail-low move sorted first to >>search? If you do, you die. It will _always_ fail low and you enter a loop >>that won't terminate until time runs out. That is the problem here, at least in >>Crafty. you get an infinite loop that will eventually have to play the very move >>that failed low... Not what you intended... > >If your search window on the retry is (-infinity, infinity), it won't fail low >;) Correct. But then you get the _same_ loop anyway. Now the fail-low move will agaim appear best because no cutoffs via hash can happen, you get back to the same depth, with the same best move, get the same fail-low again. Repeat until tired. :) This doesn't happen often, but when it does, it is a game-loser...
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