Author: Robert Hyatt
Date: 11:20:24 03/08/04
Go up one level in this thread
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... This is a problem because the oroginal hash info on the fail low will cause any re-search to a shallower depth to instantly fail low... and there starts the loop. BTW... I have seriously hurt my right hand, and as a result, I can't use it for at least four weeks as it recovers from surgery. As a result, my explanations will likely be a bit short and/or cryptic for obvious reasons... But I'll still try to respond as necessary to questions, but typing/programming will be very slow for a while. :(
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