Author: Ron Murawski
Date: 14:18:37 07/22/02
Go up one level in this thread
On July 19, 2002 at 23:01:01, Robert Hyatt wrote: >On July 19, 2002 at 12:46:57, Ron Murawski wrote: > >>On July 19, 2002 at 01:54:47, Steffen Jakob wrote: >> >>>On July 18, 2002 at 23:52:40, Ron Murawski wrote: >>> >>>>On July 18, 2002 at 22:24:13, K. Burcham wrote: >>>> >>>>> >>>>>here GM Timman 2623 FIDE played 14.Nxf6 >>>>>is there any program that prefers to exchange Knights at f6, instead of the pawn >>>>>capture at e7? >>>>> >>>>>kburcham >>>>> >>>>> >>>>> >>>>> [D] rnbq1r2/4ppkp/p2p1np1/3N4/1p1N4/4Q2P/PPP2PP1/2KR1B1R w - - 0 1 >>>> >>>>On a 1.8GHz AMD, it takes the latest Horizon beta 14.12 seconds to find Nb6. >>>>Horizon agrees with Chessmaster that this is the best move. >>>> >>>>Depth Score Time Nodes pv >>>> 4 47 44 16293 Nxe7 Re8 Re1 Kh8 >>>> 4 115 44 16673 Nxf6 exf6 Qe4 Ra7 >>>> 4 128 49 17552 Nxb4 Kh8 Qh6 Ra7 >>>> 4 137 49 19005 Bc4 Kh8 Nxe7 Ra7 >>>> 5 79? 55 30021 Bc4 Bb7 Ne6+ fxe6 Bxa6 >>>> 5 115 60 35197 Nxb4 Kh8 Qf3 Ra7 Bc4 >>>> 5 142 60 41915 Nxe7 Bb7 Ndf5+ Kh8 Qh6 d5 >>>> 6 128 82 103073 Nxe7 Re8 Re1 Kh8 Bc4 Ra7 >>>> 7 111 143 279955 Nxe7 Re8 Re1 Bb7 f3 Be4 Bd3 Rxe7 fxe4 >>>> 8 82? 247 652614 Nxe7 Re8 Re1 Qc7 Qf3 Ra7 Kd2 >>>> 8 82 478 1481058 Nxe7 Kh8 Qf3 d5 Nxc8 Ng8 >>>> 9 61 604 1889811 Nxe7 Re8 Qf3 Rxe7 Qxa8 Bb7 Qa7 Bxg2 Qxe7 Qxe7 >>>> Bxg2 >>>> 9 111! 1412 4493054 Nb6 Qxb6 Nf5+ Bxf5 Qxb6 Bxh3 Rxh3 >>> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ >>>That is a weird PV! >>> >>>Greetings, >>>Steffen. >>> >> >>Yes, it *is* a weird pv. I have noticed weird lines in Horizon's pv from time to >>time, but they tend to get replaced quickly. Most of the time the first move in >>the pv is correct, but every once and a while Horizon can lose a game due to >>this. I suppose it is caused by search instabilities. I've been searching for >>this bug for a long time. When I again try and find/fix this bug I will attempt >>to choose a "better" sequence of 64-bit random numbers for my Zobrist hashing. >>I'm running out of ideas as to the cause of the occasional pv weirdness. >> >>Ron >> >>>> 9 114 1648 5265170 Nb6 Bb7 Nxa8 Bxa8 Be2 Bxg2 Rhg1 Be4 Qg5 >>>> 10 89 2422 7893348 Nb6 Bb7 Nxa8 Bxa8 Kb1 e5 Nf3 Bxf3 Qxf3 d5 >>>> 11 117 5471 17568997 Nb6 Ra7 Nxc8 Rb7 Nxd6 exd6 Bc4 Rc7 Bb3 >>>> >>>>Ron > >Did you possibly get a fail high, and then run out of time before you got >a score? If so the PV is useless and depending on how you back it up, it >could be corrupt even. Hi Bob, No, that is not the case. As you can see from the above example at depth 9 the pv went weird and has a score associated with it. It resolved into a more believable pv about 2 1/2 seconds later. This type of behavior is usually associated with fairly substantial swing in the eval score and almost always on a fail high. I'm still looking for the bug... Ron
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