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I have just released Amoeba version 2.7.
You can download binary for windows (x86 & x64) or linux (x64) here:

https://github.com/abulmo/amoeba/releases/tag/v2.7

I expect an elo increase around 40 over Amoeba 2.6

I hope you will enjoy it.

Thank you, Richard.

Another nice improvement. Thanks.

Richard, thx

Below is Amoeba2.7 macOS executable compiled with ldc2:

https://www.dropbox.com/s/g6aol1036jawb ... r.zip?dl=0

A position Amoeba has some trouble to analyze:

[d] r3bk2/2P1npp1/2qNp2p/3pP2P/5PP1/Q2B1K2/1R6/8 w - - 5 46

Hope this helps to improve the engine.

Maarten Claessens wrote:A position Amoeba has some trouble to analyze:

[d] r3bk2/2P1npp1/2qNp2p/3pP2P/5PP1/Q2B1K2/1R6/8 w - - 5 46

Hope this helps to improve the engine.

Not using an engine here, but wouldn't you just play 1.Qxa8 Qxa8 2.Rb8 Qc6 3. Bb5 +-?

Indeed but look at this (Amoeba with 512 Mb hash): Up to ply 23 the engine wants to play Rb8?? and then needs quite some time to find the right move.

Maarten Claessens wrote:Indeed but look at this (Amoeba with 512 Mb hash):

Code: Select all

FEN: r3bk2/2P1npp1/2qNp2p/3pP2P/5PP1/Q2B1K2/1R6/8 w - - 5 46 

Amoeba 2.7:
  1/7	00:00	         201	801,435	+2.64	Rb2b8
  2/9	00:00	         330	892,615	+2.62	Rb2b8 d5d4+ Kf3f2
  3/11	00:00	         761	1,133,621	+7.69	Rb2b8 Qc6xc7 Qa3xa8
  4/8	00:00	       1,092	1,283,347	+7.90	Rb2b8 d5d4+ Kf3f2 Qc6xc7 Qa3xa8
  5/11	00:00	       3,205	1,654,108	+8.60	Rb2b8 d5d4+ Kf3f2 Qc6h1 Qa3xa8 Qh1h2+ Kf2e1
  6/18	00:00	       4,619	1,903,015	+9.50	Rb2b8 d5d4+ Kf3f2 Qc6h1 Qa3xa8 Qh1h2+ Kf2e1 Qh2g3+ Ke1d2
  7/15	00:00	       5,486	1,902,878	+9.50	Rb2b8 d5d4+ Kf3f2 Qc6h1 Qa3xa8 Qh1h2+ Kf2e1 Qh2g3+ Ke1d2 Qg3xf4+ Kd2c2
  8/15	00:00	       7,056	1,943,908	+9.50	Rb2b8 d5d4+ Kf3f2 Qc6h1 Qa3xa8 Qh1h2+ Kf2f3 Qh2h3+ Kf3f2 Qh3h2+ Kf2f3 Qh2h3+ Kf3f2
  9/18	00:00	      17,330	2,058,585	+9.77	Rb2b8 d5d4+ Kf3f2 Qc6h1 Qa3xa8 Qh1h2+ Kf2f3 Qh2h3+ Kf3f2 Qh3h2+ Qa8g2 Qh2xf4+ Qg2f3 Qf4d2+ Kf2f1
 10/21	00:00	      53,332	2,008,919	+12.21	Rb2b8 d5d4+ Kf3f2 Qc6h1 Qa3xa8 Qh1h2+ Qa8g2 Qh2xf4+ Qg2f3 Qf4h2+ Kf2f1 Ne7c8 Nd6xe8 Kf8xe8
 11/22	00:00	      97,009	2,172,907	+13.96	Rb2b8 d5d4+ Kf3f2 Qc6h1 Qa3xa8 Qh1h2+ Qa8g2 Qh2xf4+ Qg2f3 Qf4d2+ Kf2f1 Ne7c8 Rb8xc8 Qd2c1+ Kf1f2 Qc1e3+
 12/27	00:00	     153,787	2,274,262	+13.15	Rb2b8 g7g6 Rb8xa8 d5d4+ Kf3f2 Qc6xc7 Nd6xe8 Qc7c3 Ne8f6+ Kf8g7 Qa3xe7 Qc3d2+ Bd3e2 Qd2xf4+ Kf2g1 Qf4xe5
 13/29	00:00	     326,541	2,248,299	+17.28	Rb2b8 g7g5 Rb8xa8 d5d4+ Kf3f2 Qc6xc7 Ra8xe8+ Kf8g7 Re8xe7 Qc7xe7 Nd6f5+ e6xf5 Qa3xe7 f5xg4 f4xg5
 14/19	00:00	     368,552	2,288,362	+15.83	Rb2b8 d5d4+ Kf3f2 Qc6xc7 Rb8xa8 g7g6 Nd6xe8 Qc7c3 Ne8c7+ Kf8g7 Nc7xe6+ Kg7h7 Qa3xe7 Qc3d2+ Bd3e2 Qd2e3+ Kf2e1
 15/27	00:00	     464,798	2,400,271	+16.52	Rb2b8 g7g6 Rb8xa8 d5d4+ Kf3f2 Qc6xc7 Nd6xe8 Qc7c3 Ne8c7+ Kf8g7 Nc7xe6+ Kg7h7 Qa3xe7 Qc3d2+ Bd3e2 Qd2e3+ Kf2e1 Qe3g1+ Ke1d2
 16/23	00:00	     522,622	2,428,835	+16.54	Rb2b8 g7g6 Rb8xa8 d5d4+ Kf3f2 Qc6xc7 Nd6xe8 Qc7c3 Ne8c7+ Kf8g7 Nc7xe6+ Kg7h7 Qa3xe7 Qc3d2+ Bd3e2 Qd2e3+ Kf2e1 Qe3g3+ Ke1f1 Qg3h3+ Kf1g1
 17/30	00:00	     572,354	2,442,393	+16.54	Rb2b8 g7g6 Rb8xa8 d5d4+ Kf3f2 Qc6xc7 Nd6xe8 Qc7c3 Ne8c7+ Kf8g7 Nc7xe6+ Kg7h7 Qa3xe7 Qc3d2+ Bd3e2 Qd2e3+ Kf2e1 Qe3g3+ Ke1f1 Qg3h3+ Kf1g1 Qh3g3+ Kg1f1
 18/33	00:00	   1,287,748	2,365,205	+19.39	Rb2b8 d5d4+ Kf3f2 g7g5 Rb8xa8 Qc6xc7 Ra8xe8+ Kf8g7 Re8xe7 Qc7xe7 Nd6f5+ e6xf5 Qa3xe7 f5xg4 f4xg5 g4g3+ Kf2xg3 h6xg5 Qe7xg5+ Kg7f8 Qg5d8+ Kf8g7
 19/31	00:00	   1,406,907	2,368,794	+19.39	Rb2b8 d5d4+ Kf3f2 g7g5 Rb8xa8 Qc6xc7 Ra8xe8+ Kf8g7 Re8xe7 Qc7xe7 Nd6f5+ e6xf5 Qa3xe7 f5xg4 f4xg5 g4g3+ Kf2xg3 h6xg5 Qe7xg5+ Kg7f8 Qg5d8+ Kf8g7 Qd8xd4
 20/42	00:00	   2,027,578	2,380,571	+19.57	Rb2b8 d5d4+ Kf3f2 g7g5 Rb8xa8 Qc6xc7 Ra8xe8+ Kf8g7 Re8xe7 Qc7xe7 Nd6f5+ e6xf5 Qa3xe7 f5xg4 f4xg5 g4g3+ Kf2xg3 h6xg5 Qe7xg5+ Kg7f8 Qg5d8+ Kf8g7 Qd8xd4 Kg7h6
 21/36	00:01	   4,284,451	2,399,749	+21.71	Rb2b8 g7g5 Rb8xa8 Qc6xc7 Nd6xe8 Qc7c6 Ne8c7+ Qc6xa8 Qa3xa8+ Kf8g7 Qa8d8 Ne7c6 Nc7xe6+ f7xe6 Qd8f6+ Kg7g8 Qf6xe6+ Kg8g7 Qe6xc6 g5xf4 Qc6xd5 Kg7f8 Kf3xf4 Kf8g7
 22/36	00:02	   6,614,278	2,441,230	+23.56	Rb2b8 g7g5 Rb8xa8 Qc6xc7 Nd6xe8 Qc7c6 Ne8c7+ Qc6xa8 Qa3xa8+ Kf8g7 Qa8d8 Ne7c6 Nc7xe6+ f7xe6 Qd8f6+ Kg7g8 Qf6xe6+ Kg8g7 Qe6g6+ Kg7f8 Qg6xh6+ Kf8e7 Qh6xc6 g5xf4 Qc6xd5 Ke7f8 Kf3xf4
 23/34	00:02	   7,063,758	2,456,902	+22.76	Rb2b8 g7g5 Rb8xa8 Qc6xc7 Nd6xe8 Qc7c6 Ne8c7+ Qc6xa8 Qa3xa8+ Kf8g7 Qa8d8 Ne7c6 Nc7xe6+ f7xe6 Qd8f6+ Kg7g8 Qf6xe6+ Kg8g7 Qe6g6+ Kg7f8 Qg6xh6+ Kf8f7 Qh6g6+ Kf7f8 Qg6h6+ Kf8f7 Qh6g6+ Kf7f8 Qg6f6+ Kf8g8 Qf6xc6 g5xf4

24/74	06:00	1,065,652,781	2,956,577	+3.89	Qa3xa8 Qc6xa8 Rb2b8 Qa8a4 Rb8xe8+ Qa4xe8 Nd6xe8 Kf8xe8 Bd3b5+ Ke8f8 f4f5 Kf8g8 f5f6 g7xf6 e5xf6 Ne7c8 Bb5d7 Nc8b6 c7c8Q+ Nb6xc8 Bd7xc8 Kg8h7 Kf3e3 e6e5 Bc8f5+ Kh7g8 Bf5c8 Kg8f8

 25/52	06:01	1,068,141,281	2,954,203	+4.18	Qa3xa8 Qc6xa8 Rb2b8 Qa8a4 Rb8xe8+ Qa4xe8 Nd6xe8 Kf8xe8 Bd3b5+ Ke8f8 f4f5 Kf8g8 f5f6 g7xf6 e5xf6 Ne7c8 Bb5d7 Nc8b6 c7c8Q+ Nb6xc8 Bd7xc8 Kg8f8 Bc8b7 Kf8e8 Kf3f4 Ke8d8 Kf4e5 Kd8d7
 26/68	06:02	1,070,062,752	2,952,790	+4.29	Qa3xa8 Qc6xa8 Rb2b8 Qa8a4 Rb8xe8+ Qa4xe8 Nd6xe8 Kf8xe8 Bd3b5+ Ke8f8 f4f5 Kf8g8 f5f6 Ne7c8 Bb5d7 Nc8b6 c7c8Q+ Nb6xc8 Bd7xc8 Kg8f8 Bc8d7 Kf8g8 Kf3e3 Kg8f8 Ke3d4 Kf8g8 Bd7c8 Kg8h7 Bc8b7
 27/47	06:03	1,073,212,971	2,950,300	+4.88	Qa3xa8 Qc6xa8 Rb2b8 Qa8a4 Rb8xe8+ Qa4xe8 Nd6xe8 Kf8xe8 Bd3b5+ Ke8f8 f4f5 e6xf5 g4xf5 Ne7c8 Bb5d7 Nc8b6 c7c8Q+ Nb6xc8 Bd7xc8 g7g6 h5xg6 f7xg6 f5xg6 Kf8g7 Bc8f5 h6h5 e5e6 Kg7f6 e6e7 Kf6xe7
 28/58	06:05	1,076,301,050	2,948,129	+4.88	Qa3xa8 Qc6xa8 Rb2b8 Qa8a4 Rb8xe8+ Qa4xe8 Nd6xe8 Kf8xe8 Bd3b5+ Ke8f8 f4f5 e6xf5 g4xf5 Ne7c8 Bb5d7 Nc8b6 c7c8Q+ Nb6xc8 Bd7xc8 g7g6 h5xg6 f7xg6 f5xg6 Kf8g7 Bc8f5 h6h5 e5e6 Kg7f6 e6e7 Kf6xe7 g6g7
 29/58	06:06	1,080,262,656	2,946,653	+4.88	Qa3xa8 Qc6xa8 Rb2b8 Qa8a4 Rb8xe8+ Qa4xe8 Nd6xe8 Kf8xe8 Bd3b5+ Ke8f8 f4f5 e6xf5 g4xf5 Ne7c8 Bb5d7 Nc8b6 c7c8Q+ Nb6xc8 Bd7xc8 g7g6 h5xg6 f7xg6 f5xg6 Kf8g7 Bc8f5 h6h5 e5e6 Kg7f6 e6e7 Kf6xe7 g6g7

Up to ply 23 the engine wants to play Rb8?? and then needs quite some time to find the right move.

Very strange indeed.

I found the line up to 3.Bb5 in about 4 seconds.

Humans have nice pruning.

BrendanJNorman wrote:

Maarten Claessens wrote:Indeed but look at this (Amoeba with 512 Mb hash):

Code: Select all

FEN: r3bk2/2P1npp1/2qNp2p/3pP2P/5PP1/Q2B1K2/1R6/8 w - - 5 46 

Amoeba 2.7:
  1/7	00:00	         201	801,435	+2.64	Rb2b8
  2/9	00:00	         330	892,615	+2.62	Rb2b8 d5d4+ Kf3f2
  3/11	00:00	         761	1,133,621	+7.69	Rb2b8 Qc6xc7 Qa3xa8
  4/8	00:00	       1,092	1,283,347	+7.90	Rb2b8 d5d4+ Kf3f2 Qc6xc7 Qa3xa8
  5/11	00:00	       3,205	1,654,108	+8.60	Rb2b8 d5d4+ Kf3f2 Qc6h1 Qa3xa8 Qh1h2+ Kf2e1
  6/18	00:00	       4,619	1,903,015	+9.50	Rb2b8 d5d4+ Kf3f2 Qc6h1 Qa3xa8 Qh1h2+ Kf2e1 Qh2g3+ Ke1d2
  7/15	00:00	       5,486	1,902,878	+9.50	Rb2b8 d5d4+ Kf3f2 Qc6h1 Qa3xa8 Qh1h2+ Kf2e1 Qh2g3+ Ke1d2 Qg3xf4+ Kd2c2
  8/15	00:00	       7,056	1,943,908	+9.50	Rb2b8 d5d4+ Kf3f2 Qc6h1 Qa3xa8 Qh1h2+ Kf2f3 Qh2h3+ Kf3f2 Qh3h2+ Kf2f3 Qh2h3+ Kf3f2
  9/18	00:00	      17,330	2,058,585	+9.77	Rb2b8 d5d4+ Kf3f2 Qc6h1 Qa3xa8 Qh1h2+ Kf2f3 Qh2h3+ Kf3f2 Qh3h2+ Qa8g2 Qh2xf4+ Qg2f3 Qf4d2+ Kf2f1
 10/21	00:00	      53,332	2,008,919	+12.21	Rb2b8 d5d4+ Kf3f2 Qc6h1 Qa3xa8 Qh1h2+ Qa8g2 Qh2xf4+ Qg2f3 Qf4h2+ Kf2f1 Ne7c8 Nd6xe8 Kf8xe8
 11/22	00:00	      97,009	2,172,907	+13.96	Rb2b8 d5d4+ Kf3f2 Qc6h1 Qa3xa8 Qh1h2+ Qa8g2 Qh2xf4+ Qg2f3 Qf4d2+ Kf2f1 Ne7c8 Rb8xc8 Qd2c1+ Kf1f2 Qc1e3+
 12/27	00:00	     153,787	2,274,262	+13.15	Rb2b8 g7g6 Rb8xa8 d5d4+ Kf3f2 Qc6xc7 Nd6xe8 Qc7c3 Ne8f6+ Kf8g7 Qa3xe7 Qc3d2+ Bd3e2 Qd2xf4+ Kf2g1 Qf4xe5
 13/29	00:00	     326,541	2,248,299	+17.28	Rb2b8 g7g5 Rb8xa8 d5d4+ Kf3f2 Qc6xc7 Ra8xe8+ Kf8g7 Re8xe7 Qc7xe7 Nd6f5+ e6xf5 Qa3xe7 f5xg4 f4xg5
 14/19	00:00	     368,552	2,288,362	+15.83	Rb2b8 d5d4+ Kf3f2 Qc6xc7 Rb8xa8 g7g6 Nd6xe8 Qc7c3 Ne8c7+ Kf8g7 Nc7xe6+ Kg7h7 Qa3xe7 Qc3d2+ Bd3e2 Qd2e3+ Kf2e1
 15/27	00:00	     464,798	2,400,271	+16.52	Rb2b8 g7g6 Rb8xa8 d5d4+ Kf3f2 Qc6xc7 Nd6xe8 Qc7c3 Ne8c7+ Kf8g7 Nc7xe6+ Kg7h7 Qa3xe7 Qc3d2+ Bd3e2 Qd2e3+ Kf2e1 Qe3g1+ Ke1d2
 16/23	00:00	     522,622	2,428,835	+16.54	Rb2b8 g7g6 Rb8xa8 d5d4+ Kf3f2 Qc6xc7 Nd6xe8 Qc7c3 Ne8c7+ Kf8g7 Nc7xe6+ Kg7h7 Qa3xe7 Qc3d2+ Bd3e2 Qd2e3+ Kf2e1 Qe3g3+ Ke1f1 Qg3h3+ Kf1g1
 17/30	00:00	     572,354	2,442,393	+16.54	Rb2b8 g7g6 Rb8xa8 d5d4+ Kf3f2 Qc6xc7 Nd6xe8 Qc7c3 Ne8c7+ Kf8g7 Nc7xe6+ Kg7h7 Qa3xe7 Qc3d2+ Bd3e2 Qd2e3+ Kf2e1 Qe3g3+ Ke1f1 Qg3h3+ Kf1g1 Qh3g3+ Kg1f1
 18/33	00:00	   1,287,748	2,365,205	+19.39	Rb2b8 d5d4+ Kf3f2 g7g5 Rb8xa8 Qc6xc7 Ra8xe8+ Kf8g7 Re8xe7 Qc7xe7 Nd6f5+ e6xf5 Qa3xe7 f5xg4 f4xg5 g4g3+ Kf2xg3 h6xg5 Qe7xg5+ Kg7f8 Qg5d8+ Kf8g7
 19/31	00:00	   1,406,907	2,368,794	+19.39	Rb2b8 d5d4+ Kf3f2 g7g5 Rb8xa8 Qc6xc7 Ra8xe8+ Kf8g7 Re8xe7 Qc7xe7 Nd6f5+ e6xf5 Qa3xe7 f5xg4 f4xg5 g4g3+ Kf2xg3 h6xg5 Qe7xg5+ Kg7f8 Qg5d8+ Kf8g7 Qd8xd4
 20/42	00:00	   2,027,578	2,380,571	+19.57	Rb2b8 d5d4+ Kf3f2 g7g5 Rb8xa8 Qc6xc7 Ra8xe8+ Kf8g7 Re8xe7 Qc7xe7 Nd6f5+ e6xf5 Qa3xe7 f5xg4 f4xg5 g4g3+ Kf2xg3 h6xg5 Qe7xg5+ Kg7f8 Qg5d8+ Kf8g7 Qd8xd4 Kg7h6
 21/36	00:01	   4,284,451	2,399,749	+21.71	Rb2b8 g7g5 Rb8xa8 Qc6xc7 Nd6xe8 Qc7c6 Ne8c7+ Qc6xa8 Qa3xa8+ Kf8g7 Qa8d8 Ne7c6 Nc7xe6+ f7xe6 Qd8f6+ Kg7g8 Qf6xe6+ Kg8g7 Qe6xc6 g5xf4 Qc6xd5 Kg7f8 Kf3xf4 Kf8g7
 22/36	00:02	   6,614,278	2,441,230	+23.56	Rb2b8 g7g5 Rb8xa8 Qc6xc7 Nd6xe8 Qc7c6 Ne8c7+ Qc6xa8 Qa3xa8+ Kf8g7 Qa8d8 Ne7c6 Nc7xe6+ f7xe6 Qd8f6+ Kg7g8 Qf6xe6+ Kg8g7 Qe6g6+ Kg7f8 Qg6xh6+ Kf8e7 Qh6xc6 g5xf4 Qc6xd5 Ke7f8 Kf3xf4
 23/34	00:02	   7,063,758	2,456,902	+22.76	Rb2b8 g7g5 Rb8xa8 Qc6xc7 Nd6xe8 Qc7c6 Ne8c7+ Qc6xa8 Qa3xa8+ Kf8g7 Qa8d8 Ne7c6 Nc7xe6+ f7xe6 Qd8f6+ Kg7g8 Qf6xe6+ Kg8g7 Qe6g6+ Kg7f8 Qg6xh6+ Kf8f7 Qh6g6+ Kf7f8 Qg6h6+ Kf8f7 Qh6g6+ Kf7f8 Qg6f6+ Kf8g8 Qf6xc6 g5xf4

24/74	06:00	1,065,652,781	2,956,577	+3.89	Qa3xa8 Qc6xa8 Rb2b8 Qa8a4 Rb8xe8+ Qa4xe8 Nd6xe8 Kf8xe8 Bd3b5+ Ke8f8 f4f5 Kf8g8 f5f6 g7xf6 e5xf6 Ne7c8 Bb5d7 Nc8b6 c7c8Q+ Nb6xc8 Bd7xc8 Kg8h7 Kf3e3 e6e5 Bc8f5+ Kh7g8 Bf5c8 Kg8f8

 25/52	06:01	1,068,141,281	2,954,203	+4.18	Qa3xa8 Qc6xa8 Rb2b8 Qa8a4 Rb8xe8+ Qa4xe8 Nd6xe8 Kf8xe8 Bd3b5+ Ke8f8 f4f5 Kf8g8 f5f6 g7xf6 e5xf6 Ne7c8 Bb5d7 Nc8b6 c7c8Q+ Nb6xc8 Bd7xc8 Kg8f8 Bc8b7 Kf8e8 Kf3f4 Ke8d8 Kf4e5 Kd8d7
 26/68	06:02	1,070,062,752	2,952,790	+4.29	Qa3xa8 Qc6xa8 Rb2b8 Qa8a4 Rb8xe8+ Qa4xe8 Nd6xe8 Kf8xe8 Bd3b5+ Ke8f8 f4f5 Kf8g8 f5f6 Ne7c8 Bb5d7 Nc8b6 c7c8Q+ Nb6xc8 Bd7xc8 Kg8f8 Bc8d7 Kf8g8 Kf3e3 Kg8f8 Ke3d4 Kf8g8 Bd7c8 Kg8h7 Bc8b7
 27/47	06:03	1,073,212,971	2,950,300	+4.88	Qa3xa8 Qc6xa8 Rb2b8 Qa8a4 Rb8xe8+ Qa4xe8 Nd6xe8 Kf8xe8 Bd3b5+ Ke8f8 f4f5 e6xf5 g4xf5 Ne7c8 Bb5d7 Nc8b6 c7c8Q+ Nb6xc8 Bd7xc8 g7g6 h5xg6 f7xg6 f5xg6 Kf8g7 Bc8f5 h6h5 e5e6 Kg7f6 e6e7 Kf6xe7
 28/58	06:05	1,076,301,050	2,948,129	+4.88	Qa3xa8 Qc6xa8 Rb2b8 Qa8a4 Rb8xe8+ Qa4xe8 Nd6xe8 Kf8xe8 Bd3b5+ Ke8f8 f4f5 e6xf5 g4xf5 Ne7c8 Bb5d7 Nc8b6 c7c8Q+ Nb6xc8 Bd7xc8 g7g6 h5xg6 f7xg6 f5xg6 Kf8g7 Bc8f5 h6h5 e5e6 Kg7f6 e6e7 Kf6xe7 g6g7
 29/58	06:06	1,080,262,656	2,946,653	+4.88	Qa3xa8 Qc6xa8 Rb2b8 Qa8a4 Rb8xe8+ Qa4xe8 Nd6xe8 Kf8xe8 Bd3b5+ Ke8f8 f4f5 e6xf5 g4xf5 Ne7c8 Bb5d7 Nc8b6 c7c8Q+ Nb6xc8 Bd7xc8 g7g6 h5xg6 f7xg6 f5xg6 Kf8g7 Bc8f5 h6h5 e5e6 Kg7f6 e6e7 Kf6xe7 g6g7

Up to ply 23 the engine wants to play Rb8?? and then needs quite some time to find the right move.

Very strange indeed.

I found the line up to 3.Bb5 in about 4 seconds.

Humans have nice pruning.

Well, 3. Bb5 is not the best move as that allows 3. ... Qc3+ with a perpetual check. 3. Rxe8+ is much stronger.

I applaud your ability to spot the first couple of moves in a mere 4 seconds though! That is impressive to me as within the first 5 seconds, I'm still taking stock of the position on the board and haven't even started to look at possible moves!

royb wrote:

BrendanJNorman wrote:

Maarten Claessens wrote:Indeed but look at this (Amoeba with 512 Mb hash):

Code: Select all

FEN: r3bk2/2P1npp1/2qNp2p/3pP2P/5PP1/Q2B1K2/1R6/8 w - - 5 46 

Amoeba 2.7:
  1/7	00:00	         201	801,435	+2.64	Rb2b8
  2/9	00:00	         330	892,615	+2.62	Rb2b8 d5d4+ Kf3f2
  3/11	00:00	         761	1,133,621	+7.69	Rb2b8 Qc6xc7 Qa3xa8
  4/8	00:00	       1,092	1,283,347	+7.90	Rb2b8 d5d4+ Kf3f2 Qc6xc7 Qa3xa8
  5/11	00:00	       3,205	1,654,108	+8.60	Rb2b8 d5d4+ Kf3f2 Qc6h1 Qa3xa8 Qh1h2+ Kf2e1
  6/18	00:00	       4,619	1,903,015	+9.50	Rb2b8 d5d4+ Kf3f2 Qc6h1 Qa3xa8 Qh1h2+ Kf2e1 Qh2g3+ Ke1d2
  7/15	00:00	       5,486	1,902,878	+9.50	Rb2b8 d5d4+ Kf3f2 Qc6h1 Qa3xa8 Qh1h2+ Kf2e1 Qh2g3+ Ke1d2 Qg3xf4+ Kd2c2
  8/15	00:00	       7,056	1,943,908	+9.50	Rb2b8 d5d4+ Kf3f2 Qc6h1 Qa3xa8 Qh1h2+ Kf2f3 Qh2h3+ Kf3f2 Qh3h2+ Kf2f3 Qh2h3+ Kf3f2
  9/18	00:00	      17,330	2,058,585	+9.77	Rb2b8 d5d4+ Kf3f2 Qc6h1 Qa3xa8 Qh1h2+ Kf2f3 Qh2h3+ Kf3f2 Qh3h2+ Qa8g2 Qh2xf4+ Qg2f3 Qf4d2+ Kf2f1
 10/21	00:00	      53,332	2,008,919	+12.21	Rb2b8 d5d4+ Kf3f2 Qc6h1 Qa3xa8 Qh1h2+ Qa8g2 Qh2xf4+ Qg2f3 Qf4h2+ Kf2f1 Ne7c8 Nd6xe8 Kf8xe8
 11/22	00:00	      97,009	2,172,907	+13.96	Rb2b8 d5d4+ Kf3f2 Qc6h1 Qa3xa8 Qh1h2+ Qa8g2 Qh2xf4+ Qg2f3 Qf4d2+ Kf2f1 Ne7c8 Rb8xc8 Qd2c1+ Kf1f2 Qc1e3+
 12/27	00:00	     153,787	2,274,262	+13.15	Rb2b8 g7g6 Rb8xa8 d5d4+ Kf3f2 Qc6xc7 Nd6xe8 Qc7c3 Ne8f6+ Kf8g7 Qa3xe7 Qc3d2+ Bd3e2 Qd2xf4+ Kf2g1 Qf4xe5
 13/29	00:00	     326,541	2,248,299	+17.28	Rb2b8 g7g5 Rb8xa8 d5d4+ Kf3f2 Qc6xc7 Ra8xe8+ Kf8g7 Re8xe7 Qc7xe7 Nd6f5+ e6xf5 Qa3xe7 f5xg4 f4xg5
 14/19	00:00	     368,552	2,288,362	+15.83	Rb2b8 d5d4+ Kf3f2 Qc6xc7 Rb8xa8 g7g6 Nd6xe8 Qc7c3 Ne8c7+ Kf8g7 Nc7xe6+ Kg7h7 Qa3xe7 Qc3d2+ Bd3e2 Qd2e3+ Kf2e1
 15/27	00:00	     464,798	2,400,271	+16.52	Rb2b8 g7g6 Rb8xa8 d5d4+ Kf3f2 Qc6xc7 Nd6xe8 Qc7c3 Ne8c7+ Kf8g7 Nc7xe6+ Kg7h7 Qa3xe7 Qc3d2+ Bd3e2 Qd2e3+ Kf2e1 Qe3g1+ Ke1d2
 16/23	00:00	     522,622	2,428,835	+16.54	Rb2b8 g7g6 Rb8xa8 d5d4+ Kf3f2 Qc6xc7 Nd6xe8 Qc7c3 Ne8c7+ Kf8g7 Nc7xe6+ Kg7h7 Qa3xe7 Qc3d2+ Bd3e2 Qd2e3+ Kf2e1 Qe3g3+ Ke1f1 Qg3h3+ Kf1g1
 17/30	00:00	     572,354	2,442,393	+16.54	Rb2b8 g7g6 Rb8xa8 d5d4+ Kf3f2 Qc6xc7 Nd6xe8 Qc7c3 Ne8c7+ Kf8g7 Nc7xe6+ Kg7h7 Qa3xe7 Qc3d2+ Bd3e2 Qd2e3+ Kf2e1 Qe3g3+ Ke1f1 Qg3h3+ Kf1g1 Qh3g3+ Kg1f1
 18/33	00:00	   1,287,748	2,365,205	+19.39	Rb2b8 d5d4+ Kf3f2 g7g5 Rb8xa8 Qc6xc7 Ra8xe8+ Kf8g7 Re8xe7 Qc7xe7 Nd6f5+ e6xf5 Qa3xe7 f5xg4 f4xg5 g4g3+ Kf2xg3 h6xg5 Qe7xg5+ Kg7f8 Qg5d8+ Kf8g7
 19/31	00:00	   1,406,907	2,368,794	+19.39	Rb2b8 d5d4+ Kf3f2 g7g5 Rb8xa8 Qc6xc7 Ra8xe8+ Kf8g7 Re8xe7 Qc7xe7 Nd6f5+ e6xf5 Qa3xe7 f5xg4 f4xg5 g4g3+ Kf2xg3 h6xg5 Qe7xg5+ Kg7f8 Qg5d8+ Kf8g7 Qd8xd4
 20/42	00:00	   2,027,578	2,380,571	+19.57	Rb2b8 d5d4+ Kf3f2 g7g5 Rb8xa8 Qc6xc7 Ra8xe8+ Kf8g7 Re8xe7 Qc7xe7 Nd6f5+ e6xf5 Qa3xe7 f5xg4 f4xg5 g4g3+ Kf2xg3 h6xg5 Qe7xg5+ Kg7f8 Qg5d8+ Kf8g7 Qd8xd4 Kg7h6
 21/36	00:01	   4,284,451	2,399,749	+21.71	Rb2b8 g7g5 Rb8xa8 Qc6xc7 Nd6xe8 Qc7c6 Ne8c7+ Qc6xa8 Qa3xa8+ Kf8g7 Qa8d8 Ne7c6 Nc7xe6+ f7xe6 Qd8f6+ Kg7g8 Qf6xe6+ Kg8g7 Qe6xc6 g5xf4 Qc6xd5 Kg7f8 Kf3xf4 Kf8g7
 22/36	00:02	   6,614,278	2,441,230	+23.56	Rb2b8 g7g5 Rb8xa8 Qc6xc7 Nd6xe8 Qc7c6 Ne8c7+ Qc6xa8 Qa3xa8+ Kf8g7 Qa8d8 Ne7c6 Nc7xe6+ f7xe6 Qd8f6+ Kg7g8 Qf6xe6+ Kg8g7 Qe6g6+ Kg7f8 Qg6xh6+ Kf8e7 Qh6xc6 g5xf4 Qc6xd5 Ke7f8 Kf3xf4
 23/34	00:02	   7,063,758	2,456,902	+22.76	Rb2b8 g7g5 Rb8xa8 Qc6xc7 Nd6xe8 Qc7c6 Ne8c7+ Qc6xa8 Qa3xa8+ Kf8g7 Qa8d8 Ne7c6 Nc7xe6+ f7xe6 Qd8f6+ Kg7g8 Qf6xe6+ Kg8g7 Qe6g6+ Kg7f8 Qg6xh6+ Kf8f7 Qh6g6+ Kf7f8 Qg6h6+ Kf8f7 Qh6g6+ Kf7f8 Qg6f6+ Kf8g8 Qf6xc6 g5xf4

24/74	06:00	1,065,652,781	2,956,577	+3.89	Qa3xa8 Qc6xa8 Rb2b8 Qa8a4 Rb8xe8+ Qa4xe8 Nd6xe8 Kf8xe8 Bd3b5+ Ke8f8 f4f5 Kf8g8 f5f6 g7xf6 e5xf6 Ne7c8 Bb5d7 Nc8b6 c7c8Q+ Nb6xc8 Bd7xc8 Kg8h7 Kf3e3 e6e5 Bc8f5+ Kh7g8 Bf5c8 Kg8f8

 25/52	06:01	1,068,141,281	2,954,203	+4.18	Qa3xa8 Qc6xa8 Rb2b8 Qa8a4 Rb8xe8+ Qa4xe8 Nd6xe8 Kf8xe8 Bd3b5+ Ke8f8 f4f5 Kf8g8 f5f6 g7xf6 e5xf6 Ne7c8 Bb5d7 Nc8b6 c7c8Q+ Nb6xc8 Bd7xc8 Kg8f8 Bc8b7 Kf8e8 Kf3f4 Ke8d8 Kf4e5 Kd8d7
 26/68	06:02	1,070,062,752	2,952,790	+4.29	Qa3xa8 Qc6xa8 Rb2b8 Qa8a4 Rb8xe8+ Qa4xe8 Nd6xe8 Kf8xe8 Bd3b5+ Ke8f8 f4f5 Kf8g8 f5f6 Ne7c8 Bb5d7 Nc8b6 c7c8Q+ Nb6xc8 Bd7xc8 Kg8f8 Bc8d7 Kf8g8 Kf3e3 Kg8f8 Ke3d4 Kf8g8 Bd7c8 Kg8h7 Bc8b7
 27/47	06:03	1,073,212,971	2,950,300	+4.88	Qa3xa8 Qc6xa8 Rb2b8 Qa8a4 Rb8xe8+ Qa4xe8 Nd6xe8 Kf8xe8 Bd3b5+ Ke8f8 f4f5 e6xf5 g4xf5 Ne7c8 Bb5d7 Nc8b6 c7c8Q+ Nb6xc8 Bd7xc8 g7g6 h5xg6 f7xg6 f5xg6 Kf8g7 Bc8f5 h6h5 e5e6 Kg7f6 e6e7 Kf6xe7
 28/58	06:05	1,076,301,050	2,948,129	+4.88	Qa3xa8 Qc6xa8 Rb2b8 Qa8a4 Rb8xe8+ Qa4xe8 Nd6xe8 Kf8xe8 Bd3b5+ Ke8f8 f4f5 e6xf5 g4xf5 Ne7c8 Bb5d7 Nc8b6 c7c8Q+ Nb6xc8 Bd7xc8 g7g6 h5xg6 f7xg6 f5xg6 Kf8g7 Bc8f5 h6h5 e5e6 Kg7f6 e6e7 Kf6xe7 g6g7
 29/58	06:06	1,080,262,656	2,946,653	+4.88	Qa3xa8 Qc6xa8 Rb2b8 Qa8a4 Rb8xe8+ Qa4xe8 Nd6xe8 Kf8xe8 Bd3b5+ Ke8f8 f4f5 e6xf5 g4xf5 Ne7c8 Bb5d7 Nc8b6 c7c8Q+ Nb6xc8 Bd7xc8 g7g6 h5xg6 f7xg6 f5xg6 Kf8g7 Bc8f5 h6h5 e5e6 Kg7f6 e6e7 Kf6xe7 g6g7

Up to ply 23 the engine wants to play Rb8?? and then needs quite some time to find the right move.

Very strange indeed.

I found the line up to 3.Bb5 in about 4 seconds.

Humans have nice pruning.

Well, 3. Bb5 is not the best move as that allows 3. ... Qc3+ with a perpetual check. 3. Rxe8+ is much stronger.

I applaud your ability to spot the first couple of moves in a mere 4 seconds though! That is impressive to me as within the first 5 seconds, I'm still taking stock of the position on the board and haven't even started to look at possible moves!

Thanks.

Tactical themes seem to jump out at me with a quick scan at this stage, but I need to look longer to examine move-orders and examine followups (like ...Qc3 in this case).

I'm sure I'd have quickly spotted ...Qc3 with perpy with a few more seconds thought though.

Swapping everything and just Ba6 is easy as pie, but I tend to try to be clever (I'm driven by aesthetics more than winning haha), and then "refute" myself with deeper thought later.