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Up Topic The Rybka Lounge / Test Positions / a hard nut to crack.
- - By user923005 (****) [us] Date 2016-01-21 17:31
Kg2 is supposed to be the best move (and indeed, it may be a winning move) but it appears that the second most obvious move (cxd6) probably wins.
My question is, do any of your engines pop right up with Kg2, or is it extremely subtle?
I am running a batch of hard nuts at two hours each and this one seems interesting.

5bbr/3R4/3np2N/N1PkPp2/r1pP2P1/2p1PKpP/5p2/B4B1n w - - 0 1


Matefinder-x64-mingw:
2/2  00:00   72k  3,421k  -1.72  Nxg8 Rxa5
3/4  00:00   98k  3,644k  -2.52  Nxg8 Rxa5 Nf6+ Kc6 Bxc3
4/5  00:00   129k  3,795k  -2.04  Nxg8 Rxa5 Nf6+ Kc6 Bxc3
5/6  00:00   281k  4,534k  -1.61  Nxg8 Rxa5 cxd6 Rxa1 Rc7
6/8  00:00   349k  4,711k  -0.83  Nxg8 Rxg8 Bxc3 Rg7 Rxg7 Bxg7
7/10  00:00   380k  4,636k  -0.51  Nxg8 Rxa5 cxd6 c2 Nf6+ Kc6 Rc7+ Kb5 Bb2
8/10  00:00   413k  4,636k  -0.44  Nxg8 Rxa5 cxd6 g2 Bxg2 f1Q+ Bxf1 Rxg8
9/10  00:00   442k  4,604k  -0.44  Nxg8 Rxa5 cxd6 g2 Bxg2 f1Q+ Bxf1 Rxg8 Rc7
10/14  00:00   493k  4,612k  -0.41  Nxg8 Rxg8 Bxc3 Rg7 Rxg7 Bxg7 exd6 Bh6 gxf5 exf5 d7 Bg5
11/14  00:00   554k  4,651k  -0.33  Nxg8 Rxg8 Bxc3 Rg7 Rxg7 Bxg7 exd6 Bh6 gxf5 exf5 d7 Bg5
12/21  00:00   795k  4,845k  +0.06  Nxg8 Rxa5 cxd6 g2 Bxg2 f1Q+ Bxf1 Rxa1 Nf6+ Kc6 Rc7+ Kb6 Nd7+ Kb5 Bxc4+ Kb4 Bxe6
13/32  00:00   1,457k  5,147k  +0.37  Nxg8 Rxa5 cxd6 Kc6 Rc7+ Kb6 Bxc3 fxg4+ hxg4 Rxg8 Bxa5+ Kxa5 Rh7 g2 Bxg2 Bxd6 exd6 Rf8+ Ke4 Ng3+ Ke5 f1Q
14/32  00:00   3,605k  5,332k  +2.31  cxd6 g2 Bxg2 f1Q+ Bxf1 Bh7 Rc7 Bxd6 Bxc4+ Rxc4 Rxc4 Bg6 gxf5 exf5 exd6 Rxh6 Kg2
15/32  00:00   4,958k  5,497k  +1.91  cxd6 g2 Bxg2 f1B Bxf1 Rxh6 Bxc3 Rh7 Rc7 Bxd6 gxf5 exf5 exd6 Rxc7 dxc7 Be6 Bg2 Kd6 Bxh1
16/32  00:00   5,131k  5,482k  +2.46  cxd6 g2 Bxg2 f1B Bxf1 Rxh6 Bxc3 Rh7 gxf5 Rxa5 Rxh7 Bxh7 e4+ Kc6 Bxa5 exf5 d5+ Kd7 Bxc4 fxe4+ Ke3 Bxd6 Bb5+ Ke7 exd6+ Kxd6 Kd4 Bf5 Bb4+ Kc7
17/36  00:01   5,721k  5,507k  +2.63  cxd6 g2 Bxg2 f1B Bxf1 Rxh6 Bxc3 Rh7 gxf5 Rxa5 Rxh7 Bxh7 e4+ Kc6 Bxa5 exf5 d5+ Kc5 d7 Be7 Kf4 c3 Bxc3 fxe4 Bg2
18/36  00:01   7,512k  5,573k  +2.61  cxd6 g2 Bxg2 f1B Bxf1 Rxh6 Bxc3 Rh7 gxf5 Rxa5 Rxh7 Bxh7 e4+ Kc6 Bxa5 exf5 d5+ Kc5 d7 Be7 d6 Bg5 Bg2 Kc6 exf5 Bxf5 d8Q Bxd8 Bxd8 Be6 Kf4+ Kd7
19/37  00:03   21,637k  5,781k  +4.68  cxd6 g2 Bxg2 f1B Bxf1 Ng3 Nxg8 Rxg8 Kxg3 Ke4 Bxc3 Ra3 Bg2+ Kd3 Bb4 Ra4 Bf1+ Kxe3 Bc3 f4+ Kg2 Ra2+ Kg1 Rxa5 Bxa5 Kxd4 Rf7 Bh6
20/48  00:05   30,239k  5,834k  +4.98  cxd6 g2 Bxg2 f1Q+ Bxf1 Ng3 Nxg8 Rxg8 Kxg3 Ke4 Bxc3 Ra3 Bg2+ Kd3 Bb4 Ra4 Bf1+ Kxe3 Bc3 Bh6 Nxc4+ Ke4 Rf7 Bf4+ Kf2 Ra2+ Nb2 Be3+ Ke1 Ra1+ Ke2 Rxf1 Kxf1 Bxd4 Bxd4 Kxd4 gxf5 Kxe5 Nc4+ Kd5
21/48  00:06   36,302k  5,760k  +5.08  cxd6 g2 Bxg2 f1B Bxf1 Ng3 Nxg8 Rxg8 Kxg3 Ke4 Bxc3 Ra3 Bg2+ Kd3 Bb4 Ra4 Bf1+ Kxe3 Bc3 Bh6 Nxc4+ Ke4 Rf7 Bf4+ Kf2 Ra2+ Nb2 Be3+ Ke1 Ra1+ Ke2 Rxf1 Kxf1 Bxd4 Bxd4 Kxd4 gxf5 Kxe5 Nc4+ Kd5 fxe6 Kxc4 d7
22/48  00:08   48,753k  5,687k  +4.37  cxd6 Bxh6 Rc7 Bxe3 Kxe3 f4+ Kxf4 Kxd4 d7 Bh7 Rc8 Rxa5 Rxh8 Rd5 Rxh7 g2 Bxg2 Kd3 Bf1+ Kd2 Bxc4 c2 Bb2 Ke1 Rf7 f1Q+ Bxf1 Kxf1 Ke3+ Kg2 g5 Rxe5+ Kf4 Rd5 h4
23/48  00:10   59,136k  5,686k  +5.16  cxd6 g2 Bxg2 f1Q+ Bxf1 Ng3 Nxg8 Rxg8 Kxg3 Ke4 Bxc3 Ra3 Bg2+ Kd3 Bb4 Ra4 Bf1+ Ke4 Rb7 Bh6 Nxc4 f4+ exf4 Bxf4+ Kg2 Ra2+ Kg1 Kxd4 d7 Bh2+ Kh1 Rf2 Ba5 Rxf1+ Kxh2 Kxc4 d8Q Rxd8
24/58  00:22   127,552k  5,696k  +5.76  cxd6 g2 Bxg2 f1B Bxf1 Ng3 Nxg8 Rxg8 Kxg3 Ke4 Bxc3 Bh6 Bxc4 Bxe3 Bxe6 f4+ Kg2 f3+ Kf1 Rh8 Nb3 Rxh3 Nc5+ Kf4 Rf7+ Kg5 Ne4+ Kg6 Nf2 Rh2 Rxf3 Bxd4 d7 Rh8 Rh3 Rf8 Bf5+ Kf7
25/58  00:24   141,577k  5,703k  +5.63  cxd6 g2 Bxg2 f1B Bxf1 Ng3 Nxg8 Rxg8 Kxg3 Ke4 Bxc3 Bh6 Bxc4 Bxe3 Bxe6 f4+ Kg2 Rf8 Nb3 Ra2+ Kf1 Rf2+ Ke1 Kd3 Ba1 f3 Rc7 Re2+ Kd1 Ke4 Bf5+ Kf4 e6 Rh8 Bd3 Rh2 Rf7+ Kg3 Bc3 R2xh3 Nd2 Rh1+ Kc2
26/58  00:45   256,024k  5,607k  +5.79  cxd6 g2 Bxg2 f1Q+ Bxf1 Nf2 Rc7 Bxd6 Kxf2 Bxe5 Rc5+ Kd6 Nxc4+ Rxc4 Rxc4 Bf6 Nxg8 Bh4+ Kf3 Rxg8 Be2 Be1 gxf5 Rf8 Bd3 Rh8 Kg2 Rg8+ Kf1 Ra8 Kxe1 Rxa1+ Kf2 Rh1 f6 Rxh3 Rxc3 Rh6
27/58  00:50   283,732k  5,610k  +5.86  cxd6 g2 Bxg2 f1Q+ Bxf1 Ng3 Nxg8 Rxg8 Kxg3 Ke4 Bxc3 Ra3 Bg2+ Kd3 Bb4 Ra4 Rb7 Kxe3 Nxc4+ Kxd4 Na5 Kxe5 Nc6+ Kf6 Bc3+ Kg6 Ne5+ Kh6 d7 Be7 Bd2+ Kg7 d8Q Rxd8 Bg5 Ra3+ Kh2 Re8 Bxe7 Rxe7 Rxe7+ Kf6 Nc6 Rc3 Re8 f4
28/58  01:12   404,411k  5,561k  +5.99  cxd6 g2 Bxg2 f1Q+ Bxf1 Ng3 Nxg8 Rxg8 Kxg3 Ke4 Bxc3 Ra3 Bg2+ Kd3 Bb4 Ra4 Rb7 Kxe3 Nxc4+ Kxd4 Na5 Ke3 Bc5+ Kd3 Nc6 fxg4 h4 Bh6 d7 Bf4+ Kf2 Ra2+ Kg1 Be3+ Bxe3 Kxe3 d8Q Rxd8 Nxd8 Kf4 Nxe6+ Kg3 Bf1 Kxh4 Nd4 Ra4 Nc6 Re4 Kf2
29/58  01:53   630,901k  5,545k  +6.43  cxd6 g2 Bxg2 f1Q+ Bxf1 Ng3 Nxg8 Rxg8 Kxg3 Ke4 Bxc3 Ra3 Bg2+ Kd3 Bb4 Ra4 Rb7 Kxe3 Nxc4+ Kxd4 Na5 Kxe5 Nc6+ Kf6 Bc3+ Kg6 Ne5+ Kh6 Bd2+ f4+ Bxf4+ Rxf4 Kxf4 Bxd6 Be4 Rh8 h4 Bb8 Bg2 Bd6 Ke4 Bc5 Bf3 Rg8 g5+ Rxg5 Nf7+ Kg6 Nxg5
30/64  03:22   1,115,443k  5,510k  +6.80  cxd6 g2 Bxg2 f1Q+ Bxf1 Ng3 Nxg8 Rxg8 Kxg3 Ke4 Bxc3 Ra3 Bg2+ Kd3 Bb4 Ra4 Rb7 Bg7 Bf1+ Kxe3 Bc3 Rxa5 Bxa5 Kxd4 d7 Bxe5+ Kf2 Bf6 Rc7 fxg4 Rxc4+ Kd5 Rc8 Rg5 Bg2+ Kd6 d8R+ Bxd8 Rxd8+ Ke7 Ra8 Rf5+ Kg3 gxh3 Ra7+ Kf6 Bc3+ e5 Ra6+ Kf7 Kxh3
31/64  07:34   2,491,871k  5,482k  +8.13  cxd6 g2 Bxg2 f1Q+ Bxf1 Nf2 Kxf2 Ke4 Nxg8 Ra2+ Be2 Rxg8 Nb7 Rc2 Nc5+ Kd5 Na4 fxg4 hxg4 Bh6 Nxc3+ Kc6 Rc7+ Kb6 Rxc4 Rf8+ Kg3 Rxe2 Nxe2 Bxe3 Rc7 Bf2+ Kh3 Ra8 Bc3 Be3 Kg3 Re8 Kf3 Bg5 d5 exd5 Bd4+ Ka6 Nc3 Rf8+ Kg3 Bf4+ Kg2
32/64  09:29   3,131,620k  5,498k  +8.56  cxd6 g2 Bxg2 f1Q+ Bxf1 Nf2 Kxf2 Ke4 Nxg8 Ra2+ Be2 Rxg8 Nb7 Bh6 Nc5+ Kd5 Na4 Bxe3+ Kxe3 f4+ Kxf4 Rxa4 Ke3 Kc6 Rc7+ Kb6 Bxc3 Rh8 Bxc4 Rxh3+ Kd2 Rh2+ Kd3 Ra3 Bxe6 Rh3+ Kc2 Rh2+ Kc1 Rh3 Kb2 Ra8 Kc2 Rah8 Bd5 Rb8 e6
33/65  11:28   3,790,582k  5,507k  +8.98  cxd6 g2 Bxg2 f1Q+ Bxf1 Nf2 Kxf2 Ke4 Nxg8 Ra2+ Be2 Rxg8 Nb7 Rc2 Nc5+ Kd5 Na4 fxg4 hxg4 Bh6 Nxc3+ Kc6 Rc7+ Kb6 Rxc4 Kb7 Rb4+ Kc6 Kf3 Rc1 Bb5+ Kb7 Bd7+ Ka8 Ra4+ Kb7 Bxe6 Rd8 Ke4 Rb8 Bb2 Rc2 Rb4+ Ka7 Nb5+ Ka6 Nc7+ Ka7 Rxb8 Kxb8 Ba3 Bg5 Nd5 Bh4 Ne7
34/65  13:44   4,536,580k  5,505k  +9.15  cxd6 g2 Bxg2 f1Q+ Bxf1 Nf2 Kxf2 Ke4 Nxg8 Ra2+ Be2 Rxg8 Nb7 Kd5 Nc5 Rc2 Na4 fxg4 hxg4 Bh6 Nxc3+ Kc6 Rc7+ Kb6 Rxc4 Kb7 Rb4+ Kc6 Kf3 Rc1 Bb5+ Kb7 Bd7+ Ka8 Ra4+ Kb7 Bxe6 Rb8 Ke4 Bg5 Rb4+ Ka7 Bb2 Rc2 Nb5+ Ka6 Nc7+ Ka7 Ra4+ Kb7 Ba1 Re2 Nd5 Ra8 Rxa8 Kxa8 Nf4
35/65  17:08   5,686,527k  5,526k  +9.37  cxd6 Bxh6 Rc7 Bxe3 Kxe3 f4+ Kxf4 Kxd4 Nc6+ Kc5 Bxc3 Kb5 d7 Bh7 d8Q Rxd8 Nxd8 g2 Rb7+ Ka6 Bd4 Rb4 Ra7+ Kb5 Bxg2 Be4 Kxe4 f1Q Bxf1 Ng3+ Kf4 Nxf1 Rb7+ Ka4 Rc7 Nd2 Nxe6 Kb3 g5 Rb8 g6 Rg8 g7 Kc2 Nc5 Rd8 Kf5 Nf3 Be3 Kc3 e6 Ra8 Ra7 Rc8 e7
36/65  22:26   7,467,921k  5,545k  +9.48  cxd6 g2 Bxg2 f1Q+ Bxf1 Nf2 Nxg8 Rxg8 Kxf2 Ke4 Nb7 Ra2+ Be2 Kd5 Nc5 Rc2 Na4 fxg4 hxg4 Bh6 Nxc3+ Kc6 Rc7+ Kb6 Rxc4 Kb7 Rb4+ Kc6 Kf3 Rc1 Bb5+ Kb7 Bd7+ Ka8 Ra4+ Kb7 Bxe6 Rb8 Ke4 Bg5 Rb4+ Ka7 Bb2 Rxb4 Bxc1 Rb8 Kf5 Bh4 g5 Rf8+ Kg4 Be1 Nd5 Ka6 g6 Kb5
37/76  38:53   13,066,729k  5,599k  +10.11  cxd6 Bxh6 Rc7 Bxe3 Kxe3 f4+ Kxf4 Kxd4 Nc6+ Kc5 Bxc3 Kb5 d7 Bh7 d8R Rxd8 Nxd8 g2 Rb7+ Ka6 Bd4 Rb4 Ra7+ Kb5 Bxg2 Be4 Kxe4 f1Q Bxf1 Ng3+ Kf4 Nxf1 Rb7+ Ka4 Rc7 Rb8 Rxc4+ Kb5 Rc5+ Ka4 Nxe6 Nd2 Bc3 Nb3 Rc4+ Ka3 Kf5 Ra8 g5 Nc1 Nc5 Na2 Bd4 Nb4 Rc3+ Ka2 Rc1 Rf8+ Kg4 Ka3 Ra1+ Na2 g6
Parent - - By kgburcham (***) [us] Date 2016-01-22 01:16
5bbr/3R4/3np2N/N1PkPp2/r1pP2P1/2p1PKpP/5p2/B4B1n w - - 0 1


8 processor(s) found, POPCNT available
NUMA configuration with 1 node(s), offset 0
8192 MB Hash
Nalimov 6 men EGTB available - 999 MB cache
Engine: Houdini 4 Pro x64 (8192 MB)
by Robert Houdart

12/53   0:00   +3.34++  1.cxd6 (13.453.439) 16131  TB:2
12/53   0:00   +3.20   1.cxd6 g2 2.Bxg2 f1Q+ 3.Bxf1 Rxh6 4.Bxc3 Rh7 5.gxf5 exf5 6.Rd8 Rf7 7.Bg2 Ra2 8.Bxh1 Rh2 9.Bg2 Rxg2 10.Kxg2 f4 11.e4+ Kxe4 12.Nxc4 Rg7+ 13.Kf2 Bxc4 14.Rxf8 (13.553.300) 16096  TB:2
13/53   0:00   +3.33++  1.cxd6 (15.055.811) 16189  TB:2
13/53   0:01   +3.58   1.cxd6 g2 2.Bxg2 f1Q+ 3.Bxf1 Rxh6 4.Bxc3 Rh7 5.gxf5 exf5 6.Rd8 Rg7 7.Rxf8 Be6 8.Rb8 Bd7 9.Rb7 Ng3 10.Rxd7 Rxd7 11.Kxg3 Rg7+ 12.Kf4 Ra7 13.Nxc4 Rxc4 14.Bxc4+ (16.563.082) 16302  TB:2
14/53   0:01   +3.64   1.cxd6 g2 2.Bxg2 f1Q+ 3.Bxf1 Rxh6 4.Bxc3 Rh7 5.gxf5 exf5 6.Rd8 Rg7 7.Rxf8 Be6 8.Rb8 Bd7 9.Rb7 Ng3 10.Rxd7 Rxd7 11.Kxg3 Rg7+ 12.Kf4 Ra7 13.Nxc4 Rxc4 14.Bxc4+ (21.099.569) 16785  TB:2
15/53   0:01   +3.79++  1.cxd6 (28.247.697) 17447  TB:2
15/53   0:01   +3.73   1.cxd6 g2 2.Bxg2 f1Q+ 3.Bxf1 Rxh6 4.Bxc3 Rh7 5.gxf5 Rxa5 6.Rxh7 Bxh7 7.e4+ Kc6 8.Bxa5 exf5 9.exf5 Bxf5 10.Bxc4 Bxh3 11.Bb4 Bg7 12.d5+ Kb6 13.e6 Be5 14.d7 (29.478.452) 17473  TB:2
16/53   0:02   +3.58--  1.cxd6 g2 (41.731.553) 17925  TB:2
16/56   0:04   +3.68   1.cxd6 g2 2.Bxg2 f1Q+ 3.Bxf1 Rxh6 4.Bxc3 Rh7 5.gxf5 Rxa5 6.Rxh7 Bxh7 7.e4+ Kc6 8.Bxa5 exf5 9.exf5 Bg8 10.e6 Bxd6 11.Bxc4 Ng3 12.f6 Bh7 13.Ba2 Bf5 14.h4 (76.479.912) 19115  TB:8
17/57   0:05   +3.68   1.cxd6 g2 2.Bxg2 f1Q+ 3.Bxf1 Rxh6 4.Bxc3 Rh7 5.gxf5 Rxa5 6.Rxh7 Bxh7 7.e4+ Kc6 8.Bxa5 exf5 9.exf5 Bg8 10.e6 Bxd6 11.Bxc4 Ng3 12.f6 Bh7 13.Ba2 Bc2 14.d5+ (109.771.603) 19588  TB:19
17/58   0:21   +3.83++  1.Ke2 (471.404.554) 22035  TB:23
17/59   0:22   +4.14++  1.Ke2 (485.418.679) 22004  TB:23
other best move - reduce depth to 14
14/61   0:22   +4.92++  1.Ke2 (487.891.768) 21990  TB:23
14/61   0:22   +4.36   1.Ke2 Ra2+ 2.Bb2 Rxb2+ 3.Kf3 Rb4 4.c6 Bf7 5.Nxf7 g2 6.Bxg2 f1B 7.Bxf1 Rxh3+ 8.Bxh3 Rb2 9.Kf4 Rf2+ 10.Kg5 c2 11.c7 c1Q 12.c8Q Ke4 13.Nxd6+ Bxd6 14.Nxc4 (489.277.546) 21959  TB:23
15/61   0:22   +4.54++  1.Ke2 (490.324.024) 21940  TB:23
15/61   0:22   +4.90++  1.Ke2 (491.691.948) 21923  TB:23
15/61   0:22   +5.03   1.Ke2 Ra2+ 2.Bb2 Rxb2+ 3.Kf3 Rb4 4.c6 Bf7 5.Nxf7 g2 6.Bxg2 f1B 7.Bxf1 Rxh3+ 8.Bxh3 Rb2 9.Kf4 Rf2+ 10.Kg5 c2 11.c7 c1Q 12.c8Q Ke4 13.Nxd6+ Bxd6 14.Nxc4 (492.449.637) 21910  TB:23
16/61   0:23   +5.23++  1.Ke2 (508.532.823) 21820  TB:31
16/61   0:23   +5.65++  1.Ke2 (515.409.267) 21776  TB:33
16/61   0:23   +4.82--  1.Ke2 Ra2+ (521.801.729) 21763  TB:33
16/94   0:29   +6.76++  1.Ke2 (633.068.500) 21298  TB:308
16/94   0:29   +6.74   1.Ke2 Ra2+ 2.Bb2 Rxb2+ 3.Kf3 Rb4 4.c6 g2 5.Bxg2 f1Q+ 6.Bxf1 Bh7 7.c7 Be7 8.Nf7 fxg4+ 9.Kf4 Ng3 10.Nxh8 Nh5+ 11.Kxg4 Ke4 12.Rxd6 Bf5+ 13.Kxh5 c2 14.c8Q (633.228.504) 21292  TB:310
17/94   0:30   +6.46--  1.Ke2 Ra2+ (649.971.704) 21253  TB:321
17/94   0:32   +7.02++  1.Ke2 (686.689.647) 21236  TB:341
17/94   0:32   +7.07   1.Ke2 Ra2+ 2.Bb2 Rxb2+ 3.Kf3 Rb4 4.c6 g2 5.Bxg2 f1Q+ 6.Bxf1 Bh7 7.c7 Be7 8.Nf7 fxg4+ 9.Kf4 Ng3 10.Nxh8 Bg5+ 11.Kxg5 Ke4 12.exd6 Rb5+ 13.Kf6 Rf5+ 14.Kxe6 (699.616.544) 21201  TB:345
18/94   0:35   +7.36++  1.Ke2 (754.511.608) 21159  TB:374
18/94   0:35   +7.02   1.Ke2 Ra2+ 2.Bb2 Rxb2+ 3.Kf3 Rb4 4.c6 g2 5.Bxg2 f1Q+ 6.Bxf1 Bh7 7.c7 Be7 8.Nf7 fxg4+ 9.Kf4 Ng3 10.Nxh8 Nh5+ 11.Kxg4 Ke4 12.Rxd6 Bf5+ 13.Kxh5 c2 14.c8Q (756.752.282) 21146  TB:374
19/94   0:39   +7.31++  1.Ke2 (825.407.175) 21116  TB:405
19/94   0:41   +7.58   1.Ke2 Ra2+ 2.Bb2 Rxb2+ 3.Kf3 Rb4 4.c6 g2 5.Bxg2 f1Q+ 6.Bxf1 Bh7 7.c7 Be7 8.Nf7 fxg4+ 9.Kf4 Ng3 10.Nxh8 Bg5+ 11.Kxg5 Ke4 12.exd6 Rb5+ 13.Kf6 c2 14.Nxc4 (885.944.023) 21134  TB:431
20/94   0:56   +7.89++  1.Ke2 (1.210.054.626) 21422  TB:509
20/94   1:00   +8.01   1.Ke2 Ra2+ 2.Bb2 Rxb2+ 3.Kf3 Rb4 4.c6 g2 5.Bxg2 f1Q+ 6.Bxf1 Bh7 7.c7 Be7 8.Nf7 fxg4+ 9.Kf4 Ng3 10.Nxh8 Bg5+ 11.Kxg5 Ke4 12.exd6 Rb5+ 13.Kf6 c2 14.Nxc4 (1.305.730.995) 21445  TB:554
21/94   1:25   +8.18   1.Ke2 Ra2+ 2.Bb2 Rxb2+ 3.Kf3 Rb4 4.c6 g2 5.Bxg2 f1Q+ 6.Bxf1 Bh7 7.c7 Be7 8.Nf7 fxg4+ 9.Kf4 Ng3 10.Nxh8 Nh5+ 11.Kxg4 Ke4 12.Rxd6 Bf5+ 13.Kxh5 c2 14.c8Q (1.853.974.092) 21757  TB:703
22/94   1:46   +7.84--  1.Ke2 Ra2+ (2.339.755.289) 21993  TB:775
22/94   3:17   +8.52++  1.Ke2 (4.479.477.693) 22628  TB:1.584
22/94   3:34   +8.59   1.Ke2 Ra2+ 2.Bb2 Rxb2+ 3.Kf3 Rb4 4.c6 g2 5.Bxg2 f1Q+ 6.Bxf1 Bh7 7.c7 Be7 8.Nf7 fxg4+ 9.Kf4 Ng3 10.Nxh8 Nh5+ 11.Kxg4 Ke4 12.Rxd6 Bf5+ 13.Kxh5 c2 14.c8Q (4.856.777.293) 22594  TB:1.712
23/94   4:16   +8.23--  1.Ke2 Ra2+ (5.837.392.592) 22719  TB:1.877
Parent - By user923005 (****) [us] Date 2016-01-22 04:31
It seems likely Ke2 is a bit better.
I added an option to matefinder to turn off null move reductions, and it still can't find the better move.  I guess that the problem is that the knight capture also wins.
However, it does solve the first 3 in this set much more quickly:

4rk2/2P2p2/p4P2/2p2b2/2p5/8/P7/2KR4 w - -

2b1rk2/5p2/p1P5/2p2P2/2p5/7B/P7/2KR4 w - -

brqqqqqk/B6q/R6q/Q2Nn2q/Q2nN2q/Q6r/Q6b/KQQQQQRB w - -

5bbr/3R4/3np2N/N1PkPp2/r1pP2P1/2p1PKpP/5p2/B4B1n w - -


The third problem crashes some engines (including Komodo with null move turned off after a few minutes of search).
Sting crashed on the 2nd one.
Parent - - By Akbarfan (***) Date 2016-01-22 01:27 Edited 2016-01-22 01:30
1. Kg2 is clearly a losing move:

After 1.Kg2

Analysis by Stockfish 090116 64 1T:
1...Txa1 2.h4 c2 3.Kh3 Txf1 4.h5 Tg1 5.Kh4 c1D 6.Sxc4 Lxh6 7.Sxd6 Kc6 8.Tb7 f1D 9.Tb6+ Kd5 10.Sxf5 exf5 11.Td6+ Ke4 12.Tg6 Dxe3 13.e6 fxg4 14.Txg4+ Kd5 15.c6 Lxe6
  -+  (-38.23)   Tiefe: 23/46   00:13:44  877MN, tb=17

Edit: ah, i see you mean 1.Ke2
Parent - By user923005 (****) [us] Date 2016-01-22 04:32
Yes, sorry.  I gave the wrong solution in my original post.
Up Topic The Rybka Lounge / Test Positions / a hard nut to crack.

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