Author: Ricardo Gibert
Date: 13:23:39 04/24/05
Go up one level in this thread
On April 24, 2005 at 15:05:41, John Merlino wrote: >On April 24, 2005 at 14:31:52, Jack Lad wrote: > >>[d] 6nr/p2rkp1n/1pQRq1pp/1N2P3/8/4BN1P/PPP2PP1/2K4R w >> >>1.Nc7 or Nfd4? >> >>Or can they both mate in the same number of moves? > >Playing through the lines, it appears that: > >1.Nc7 is a Mate in 9. > >1.Nfd4 is a Mate in 11. > >jm Your "Playing through the lines,..." raised an alarm bell in my mind, so I decided to feed this to Ruffian. First I fed it it the position after 1.Nc7 and got this after 10 minutes on my 1.3Ghz Centrino: Ruffian 1.0.1 UCI 13 MB: D1 00:00 9.15 Rxd6 exd6 Qxd6 D2 00:00 M1 Rxd6 Qe8 D2 00:00 9.94 Qf5 Nd5 Ke8 D3 00:00 12.46 Qf5 Nd5 Kf8 Rxd7 D4 00:00 15.43 Qf5 g4 Qxc2 Qxc2 Rxd6 exd6 Kxd6 D4 00:00 14.21 Rxc7 Qxc7 Kf8 Rxe6 fxe6 Qxa7 D5 00:00 14.79 Rxc7 Rxe6 fxe6 Qxc7 Kf8 Qc8 Ke7 Bxh6 D6 00:00 15.42 Rxc7 Rxe6 fxe6 Qxc7 Kf8 Qb8 Kf7 Qxa7 Ne7 Bxh6 D6 00:00 14.72 Nf8 Nxe6 fxe6 Rxd7 Nxd7 Qd6 Kd8 Qxe6 Ne7 D7 00:00 15.89 Nf8 Nxe6 fxe6 Rxd7 Nxd7 Rd1 Nxe5 Qc7 Nd7 Rxd7 Kf6 D7 00:00 15.40 Rxc7 Rxe6 fxe6 Qxc7 Kf8 Qb8 Kf7 Qxa7 Ne7 Bxh6 Nf8 D8 00:01 19.14 Rxc7 Rxe6 Kf8 Re8 Kg7 Qxc7 Ng5 Nxg5 hxg5 Bxg5 Nh6 D8 00:02 18.00 Nf8 Nxe6 fxe6 Rxd7 Nxd7 Rd1 Kf7 Rxd7 Ne7 Rxa7 Rc8 Qxb6 D9+ 00:03 18.35 Nf8 D9 00:09 22.01 Nf8 Rhd1 Rh7 Nxe6 Nxe6 Qxd7 Kf8 Rxe6 fxe6 Qxh7 g5 Qxa7 D9 00:10 19.99 Rxc7 Rxe6 Kf8 Re8 Kg7 Qxc7 Ng5 Nxg5 hxg5 Qxa7 b5 Bxg5 D9 00:19 19.05 Qf5 g4 Qxc2 Kxc2 Rxc7 Qxc7 Kf8 Qxa7 Kg7 Qxb6 Ne7 D10+ 00:20 19.40 Qf5 D10 00:39 M10 Qf5 Nd4 Nhf6 Nxf5 gxf5 Rxd7 Nxd7 Qd6 Kd8 Rd1 Ngf6 exf6 Kc8 Qxd7 Kb7 Qd5 Kxc7 Bf4 Kc8 Qd7 D10 00:54 25.83 Nf8 Rhd1 Rh7 Nxe6 Nxe6 Qc8 Rxd6 exd6 Kf6 Qc3 Nd4 Qxd4 Ke6 d7 Kf5 d8Q D10 00:58 21.75 Rxc7 Rxe6 Kf8 Re8 Kg7 Qxc7 Ng5 Bd4 Ne6 Rxe6 b5 Rd6 b4 Qxa7 D11+ 01:06 22.10 Rxc7 D11 01:12 23.05 Rxc7 Rxe6 fxe6 Qxc7 Kf8 Rd1 Ne7 Qd8 Kf7 Qxh8 b5 Qxh7 Ke8 Qh8 Kf7 Bxh6 b4 D12+ 01:22 23.40 Rxc7 D12 01:38 M10 Rxc7 Rxe6 Kf8 Qd6 Re7 Rxe7 g5 Rxf7 Kxf7 e6 Kg6 Ne5 Kg7 Qd7 Kf6 Ng4 Kf5 e7 Kg6 e8Q D12 03:41 24.59 Nf8 Nxe6 fxe6 Rxd7 Nxd7 Rd1 Kf7 Bxh6 g5 Rxd7 Ne7 Nxg5 Kg6 Qxe6 Kh5 g4 Kh4 Rxe7 Rxh6 Qxh6 D13+ 03:58 24.94 Nf8 D13 09:29 25.22 Nf8 Nxe6 fxe6 Rxd7 Nxd7 Rd1 Kf7 Bxh6 g5 Rxd7 Ne7 Nxg5 Kg6 Qxe6 Kh5 g4 Kh4 Rxe7 Rf8 Bxf8 Kxg5 Rxa7 D14+ 10:33 25.57 Nf8 Note that it acquired a mate score a few times only to lose again. Ultimately, a mate was not found. This doesn't prove there isn't a shorter mate, but it does suggest, I think, that "Playing through the lines,..." is a dubious thing to do. I cleared the hash tables and then fed it the position after 1.Rxe6 and after only 2 minutes I got this: Ruffian 1.0.1 UCI 13 MB: D1 00:00 12.40 Nd6 D2 00:00 11.95 Nd6 Kd8 D3 00:00 12.85 Nd6 Ng5 Bxg5 hxg5 Nxg5 D4 00:00 12.47 Nd6 Rd8 Rd1 Kf8 D5 00:00 12.82 Nd6 Rd8 Nc8 Kf7 Nxa7 Ne7 Qxb6 D6 00:00 12.87 Nd6 Nf8 Rd1 Rh7 Qc8 Rg7 D7 00:00 13.68 Nd6 Rd8 Nc8 Kf8 Qxe6 Re8 Qd6 Kg7 Nxa7 D8 00:00 14.63 Nd6 Nf8 Qa8 Rd8 Qxa7 Nd7 Bxb6 Rb8 Bc7 Rf8 D9+ 00:01 14.98 Nd6 D9 00:02 15.23 Nd6 Nf8 Qa8 Rd8 Qxa7 Rd7 Qxb6 Nh7 Qc6 Kd8 Rd1 D10+ 00:04 15.58 Nd6 D10 00:04 15.65 Nd6 Nf8 Qc4 g5 Nd4 Rxd6 exd6 Kf7 d7 Ke7 Qb4 Kxd7 Qxf8 a6 D10 00:10 19.22 Rd1 Nf8 Ng5 hxg5 Bxg5 Kf7 Rxd7 Ne7 Rxa7 Kg8 Bxe7 Rh5 Qe8 D11+ 00:12 19.57 Rd1 D11 00:24 M13 Rd1 Ngf6 exf6 Nxf6 Rxd7 Nxd7 Qd6 Ke8 Nc7 Kd8 Ne5 Rh7 Nc6 Kc8 Nb5 Nb8 Qxb8 Kd7 Qb7 Ke8 Nd6 Kf8 Bxh6 Rxh6 Qf7 D12 00:39 M11 Rd1 Ngf6 Rxd7 Nxd7 Qd6 Ke8 Nc7 Kd8 Nxe6 Ke8 Ng7 Kd8 e6 Nhf6 e7 Kc8 Qc6 Kb8 Bf4 Ne5 Bxe5 D13 01:16 M10 Rd1 Ngf6 exf6 Nxf6 Rxd7 Nxd7 Qd6 Ke8 Nc7 Kd8 Nxe6 Ke8 Ng7 Kf7 Qxd7 Kg8 Ne6 h5 Qg7 D14 02:16 M10 Rd1 Ngf6 exf6 Nxf6 Rxd7 Nxd7 Qd6 Ke8 Nc7 Kd8 Nxe6 Ke8 Ng7 Kf7 Qxd7 Kg8 Ne6 h5 Qg7 It reached the same depth 5 times faster and does not seem to be in any danger of losing the mate score it found. Chess is so much easier when you just grab the Queen!
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