Author: Joachim Rang
Date: 02:59:47 05/05/05
Go up one level in this thread
But needs a bit longer ;-): 3h30 min on my Pentium M 1.6 GHz (see analysis
below). It seems to be a pruning problem for most chess programs. After Rf6 and
hxg5, white plays with a piece down for many, many plies. Reason enough for most
(all?) programs to reduce this variation. For example Shredder needs depth 24 to
see that Rf6 is the best move. After 17.Rf6 hxg5 18.Raf1 it needs only depth 17
to see that white has equalled. So in the root position Shredder reduces the
tree after 17.Rf6 by 4 plies. If I turn down the selctivity of Shredder by
changing "Playing Style" to "Soid" and disablng "Forward Pruning" by setting it
to "0", Shredder finds Rf6 already on depth 16 (8 plies less). Below are the
analysis, first with the default values and second with the "brute force"
settings (note that I restricted in the latter case the analysis to Rf6 only,
since I just wanted to find out on which iteration sees that Rf6 equals).
rn3rk1/p2q1pp1/4p2p/2ppP1NQ/P7/2P1P3/2P3PP/R4RK1 w - -
Engine: Shredder 9 UCI (256 MB)
von Stefan Meyer-Kahlen
11/22 0:01 -1.10 1.Sh3 Sc6 2.Sf4 Sa5 3.Sd3 Dc7 4.Tab1 Sc4
5.Tb5 Sxe3 6.Txc5 (498.618) 388
12/23 0:02 -0.96 1.Sh3 Sc6 2.c4 dxc4 3.Tad1 Dc7 4.Tf4 Sxe5 (998.178) 411
13/23 0:03 -1.06 1.Sh3 Sc6 2.c4 dxc4 3.Tad1 Dc7 4.Td6 Tad8
5.Tfd1 Sb4 6.De2 Sd5 7.e4 (1.577.835) 412
14/28 0:08 -0.91 1.Sh3 Sc6 2.c4 Se7 3.Sf4 dxc4 4.De2 Dc7
5.Dxc4 Dxe5 6.e4 Tad8 7.Sd3 Dd4+
8.Dxd4 (3.612.615) 428
15/30 0:18 -1.15 1.Sh3 Sc6 2.Sf2 c4 (7.919.652) 434
15/34 0:21 -1.14++ 1.Sf3 (9.336.177) 434
15/34 0:24 -1.13 1.Sf3 Sc6 2.Dg4 Dc7 3.Df4 Da5 (10.656.681) 431
16/30 0:34 -1.18 1.Sf3 Sc6 2.Dg4 Dc7 3.Df4 Da5 4.Ta3 Tab8
5.e4 c4 6.Kh1 Tb2 7.exd5 Dxd5 8.Taa1 Td8
9.Tac1 (14.996.718) 437
16/30 0:35 -1.17++ 1.Sh3 (15.657.034) 435
16/32 0:45 -0.94 1.Sh3 Sc6 2.Sf2 Dc7 3.Sg4 c4 4.e4 (19.640.732) 435
17/40 1:21 -0.99 1.Sh3 Sc6 2.Sf2 Se7 3.e4 Sg6 4.De2 Tfe8
5.c4 Sxe5 6.exd5 exd5 7.cxd5 Dxd5
8.Tad1 Dc4 9.Dxc4 Sxc4 (35.229.072) 433
18/37 1:54 -1.02 1.Sh3 Sc6 2.Sf2 Se7 3.e4 Sg6 4.De2 Tfe8
5.c4 Tad8 6.cxd5 exd5 7.Db5 dxe4
8.Dxd7 Txd7 9.Sxe4 Txe5 10.Tae1 (49.952.118) 436
19/38 2:55 -0.96 1.Sh3 Sc6 2.Sf2 Se7 3.e4 Sg6 4.De2 Dc7
5.exd5 exd5 6.c4 d4 7.Sd3 Tae8
8.Tae1 Sxe5 9.Sxe5 f6 10.Dh5 Txe5 (76.876.626) 437
20/41 5:56 -0.90 1.Sh3 Sc6 2.Sf2 Se7 3.e4 Sg6 4.Tfd1 Dc7
5.exd5 exd5 6.Df5 Se7 (154.131.394) 432
21/52 10:29 -0.87 1.Sh3 Sc6 2.Sf2 Se7 3.e4 Sg6 4.Tfd1 Dc6
5.exd5 exd5 6.c4 d4 7.Sd3 Tac8 8.c3 De4
9.cxd4 Dxd4+ (271.280.228) 430
22/53 25:46 -1.10 1.Sh3 Sc6 2.Sf2 De8 3.e4 f5 4.Dxe8 Tfxe8
5.exd5 exd5 6.Tad1 Tad8 7.Sd3 c4
8.Sb4 Sxb4 9.cxb4 Txe5 10.Tf4 Tb8
11.b5 Kf7 12.Tff1 Ke6 (668.333.153) 432
22/53 32:47 -1.09++ 1.Sf3 (849.660.464) 431
22/53 42:22 -1.09 1.Sf3 Sc6 2.c4 Tab8 3.Tad1 (1.092.825.411) 429
23/50 89:16 -1.08 1.Sf3 Sc6 2.Dh4 Dc7 3.c4 Tab8 4.cxd5 exd5
5.c3 Sxe5 (2.298.358.059) 429
24/54 166:30 -1.05 1.Sf3 Sc6 2.g4 f5 3.exf6 Txf6 4.Tf2 Taf8 (4.309.196.380)
431
24/65 210:01 -1.04++ 1.Tf6 (5.470.786.966) 434
24/65 236:09 -0.69++ 1.Tf6 (6.170.600.715) 435
24/68 480:54 +0.07 1.Tf6 hxg5 2.Taf1 Db7 3.T6f3 Sd7
4.Dxg5 Dc7 (13.209.904.577) 457
rn3rk1/p2q1pp1/4p2p/2ppP1NQ/P7/2P1P3/2P3PP/R4RK1 w - -
Engine: Shredder 9 UCI (256 MB)
von Stefan Meyer-Kahlen
9/23 0:01 -3.67 1.Tf6 hxg5 2.Tf3 g4 3.Tg3 Dc7 4.Txg4 Sd7
5.Tg5 (681.878) 489
10/22 0:02 -3.71 1.Tf6 hxg5 2.Tf3 g4 3.Tg3 Dc7 4.Txg4 Sd7
5.Th4 f5 (1.305.688) 493
11/27 0:05 -3.49 1.Tf6 hxg5 2.Tf3 g4 3.Tg3 Dc7 4.Txg4 Sd7
5.Tg5 f5 6.exf6 Sxf6 7.Dh6 (2.860.441) 506
12/29 0:11 -3.61 1.Tf6 hxg5 2.Tf3 g4 3.Tg3 Dc7 4.Txg4 Sd7
5.Tg5 g6 6.Dh6 Sxe5 7.Tf1 (6.113.967) 514
13/29 0:28 -3.58 1.Tf6 hxg5 2.Tf3 g4 3.Tg3 Sc6 4.Txg4 f6
5.exf6 Txf6 6.Tf4 Taf8 7.Taf1 e5
8.Txf6 (14.867.223) 520
14/33 1:00 -3.58 1.Tf6 hxg5 2.Tf3 g4 3.Dxg4 Sc6 4.Tg3 f6
5.exf6 Txf6 (31.256.192) 518
15/34 2:40 -3.33++ 1.Tf6 hxg5 (81.977.841) 509
15/36 5:07 -2.94 1.Tf6 hxg5 2.Taf1 Sc6 3.T1f3 g4
4.T3f4 g6 5.Txg6+ fxg6 6.Dxg6+ Dg7
7.Dxe6+ Kh7 8.Dxc6 Dxe5 (153.833.100) 499
16/38 11:05 -2.69++ 1.Tf6 hxg5 (326.573.412) 490
16/39 21:06 -2.19++ 1.Tf6 hxg5 (600.037.480) 473
16/42 46:31 -0.01 1.Tf6 hxg5 2.Taf1 Db7 3.T6f3 g4
4.Tg3 (1.240.183.456) 444
17/43 70:28 +0.06 1.Tf6 hxg5 2.Taf1 Db7 3.T6f3 Sd7
4.Txf7 Txf7 5.Dxf7+ Kh8 6.Dh5+ Kg8 (1.801.332.076) 426
On May 04, 2005 at 01:04:09, Randy Lovelace wrote:
>[D] rn3rk1/p2q1pp1/4p2p/2ppP1NQ/P7/2P1P3/2P3PP/R4RK1 w - - 0 17
>
>
>Can any program find Rf6?
>
>[Event "URS-ch06 Odessa qf1 "]
>[Site "?"]
>[Date "1929.01.01"]
>[Round "?"]
>[White "Bernstein, A"]
>[Black "Sorokin, N"]
>[Result "1-0"]
>[ECO "C17"]
>[Opening "French"]
>[Variation "Winawer, advance, Bogolyubov variation"]
>
>1.e4 e6 2.d4 d5 3.Nc3 Bb4 4.e5 c5 5.Bd2 Ne7 6.a3 Bxc3 7.bxc3 b6 8.Nf3 Ba6
>9.Bxa6 Nxa6 10.O-O Qd7 11.a4 Nb8 12.Be3 Nf5 13.dxc5 Nxe3 14.fxe3 bxc5 15.
>Ng5 O-O 16.Qh5 h6 17.Rf6 Nc6 18.Rxh6 gxh6 19.Qxh6 f6 20.exf6 Ne5 21.Rf1
>Rab8 22.Rf4 Rb1+ 23.Kf2 Rxf6 24.Qxf6 1-0
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