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Very Hot Topic (More than 25 Replies) My trusty engine tells me Chess Truth (Read 53610 times)
Smyslov_Fan
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Re: My trusty engine tells me Chess Truth
Reply #91 - 07/31/13 at 21:05:25
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Wow!

This is one of those positions I would have guessed that an engine would get right. I wonder how it missed 5.Rf6. When you plugged in the moves, did it recognise how powerful the offered sac was?
  
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Re: My trusty engine tells me Chess Truth
Reply #90 - 07/31/13 at 20:08:50
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Vass wrote on 11/15/11 at 11:13:44:
Engines good at tactics.. Really?

an example from one of my correspondence games:

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Houdini (1.5) evaluates this as completely equal giving 1.Ndf3 at depth 23
yet, black is totally lost after 1.Bxh7+! Kxh7 2.Qh5+ Kg8 3.Qxh4 Nxe5 4.fxe5 Be7 5.Rf6!! (what a wonderful move)
  
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Re: My trusty engine tells me Chess Truth
Reply #89 - 10/29/12 at 08:53:23
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trw wrote on 10/29/12 at 03:09:17:
You don't need to post your hardware just your depth reached. Depth 36 is depth 36 whether it is reached in one day via 200 cores or 10 days via 2 cores.

No doubt about it!  Wink
  
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Re: My trusty engine tells me Chess Truth
Reply #88 - 10/29/12 at 03:09:17
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You don't need to post your hardware just your depth reached. Depth 36 is depth 36 whether it is reached in one day via 200 cores or 10 days via 2 cores.
  
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Re: My trusty engine tells me Chess Truth
Reply #87 - 10/29/12 at 00:13:00
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Hmm. I haven't gone through the entire thread so apologies if this point has already been made; besides, I don't disagree with the basic idea that human + engine trumps engine.

What I notice though when people remark how engines failed to understand this position or that, and compare this engine to that, they never mention what computer they 're using, and their processor in particular. That makes a tremendous difference. It won't do you much good to employ Rybka 10 on your 10 year old budget laptop, whereas a very simple materialistic evaluation engine can go a very long way given lots of computational power.
  
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Re: My trusty engine tells me Chess Truth
Reply #86 - 10/23/12 at 22:43:03
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I just thought i'd update this thread to show the amazing advancement of Houdini 2c to Houdini3.

Houdini 2c was unable to determine that Bh3 won or was even the best move (though still to it's credit, it thought neither Be4 or a3 was winning).

However, at long last, an engine is able to determine Bh3 is winning! Houdini 3 thinks Bh3 wins (though sadly it still thinks Be4 and a3 also win).

238: Veselin Topalov - Alexey Shirov, It (cat.21) Linares (Spain) 1998
8/8/4kpp1/3p1b2/p6P/2B5/6P1/6K1 b - - 0 1

Analysis by Houdini 3 Pro x64:

1. -+  (-9.59): 47...Bh3 48.Kf2 Kf5 49.Ke3 Bxg2 50.Bb2 Be4 51.Bc3 a3 52.Kd2 Bg2 53.Kc1 Ke4 54.Bxf6 d4 55.Kb1 d3 56.Bc3 Kf3 57.Ka1 Ke2 58.Ka2 Bd5+ 59.Kxa3 d2 60.Bxd2 Kxd2 61.Kb2 Kd3 62.Kc1 Ke3 63.Kc2 Be4+ 64.Kc3

2. -+  (-1.61): 47...Be4 48.Kf2 f5 49.g3 Kd7 50.Bb2 Kc6 51.Ke3 Kc5 52.Be5 a3 53.Bd4+ Kc4 54.Be5 a2 55.Ba1 Bd3 56.Bf6 Bb1 57.Ba1 Be4 58.Bd4 Bf3 59.Bf6 Bh5 60.Bd4 Bd1

Depth 36
  
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Re: My trusty engine tells me Chess Truth
Reply #85 - 10/19/12 at 22:24:36
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Vass wrote on 11/22/11 at 07:51:19:
I think the engine's program is written economically in a way that can be described as "following the principles".. In this special case (promoting to bishop) the engine is told to consider promoting to B (instead of to queen) only if the opponent is entering into a stalemate right after a direct queen promotion. And if not a stalemate right after the promotion then a new-promoted queen is considered to be better than a new-promoted bishop, which in most of the cases (maybe 99.9 %) is true. A problem arises in this particular case when (in 0.01% maybe) a special position like this one is arranged. Anyway, I still can't figure how the strength of the engine is affected by this arrangement of the engine's "thinking process".. Maybe these + ELO points are gained because of the fact that this particular engine is "thinking" faster in some positions than the other engines which are not modified by this rule.. Who knows? Only the engine programmers maybe..  Cool

I was reminded of this discussion when I came across this webpage about minor promotion: http://timkr.home.xs4all.nl/chess2/minor.htm
At the end of the page you'll find this position (which occured in a real game) where the only winning move is a bishop promotion
  
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Re: My trusty engine tells me Chess Truth
Reply #84 - 02/16/12 at 15:58:46
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Vass wrote on 02/12/12 at 17:28:44:
I don't know what engines say about this position...but I can easily guess.  Wink

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FEN: 8/8/8/1k1p2p1/p2P2P1/P3P3/qPKN4/8 w - - 0 1

Why all these silicon beasts don't understand chess fortresses at all?
Huh


I don't get it. This looks like a trivial win for black to me. Stockfish agrees.

Update: Oops - now I do. Sorry for the noise.
  
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Re: My trusty engine tells me Chess Truth
Reply #83 - 02/16/12 at 14:17:59
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For amusement and education, I play G-15 a good deal against Shredder on my Galaxy Tab handheld. Strong program normally, but much less so on this little machine.

Anyhow, play not infrequently goes 1.e4 Nf6 2.e5 Nd5 3.Nf3 d6 4.Bc4 Nb6, and here, unaccountably and invariably, Shredder takes more than a minute to produce White's next move! What the heck is to think about?! 5.Bb3 is the only move that makes any sense.

5.Bxf7+? Kxf7 6.e6+ Kg8 -+.
« Last Edit: 02/16/12 at 15:21:30 by Markovich »  
The Great Oz has spoken!
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Re: My trusty engine tells me Chess Truth
Reply #82 - 02/15/12 at 12:37:57
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Not one of my engines (even at depth 36) found the best move here:

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FEN: 7k/6rp/6pN/5rP1/8/2B5/8/K7 b - - 0 1

...While a human chess player wil see almost immediately that 1. ...Rxg5! is the best move here and the only one that is worth considering in order to win.  Wink
  
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Re: My trusty engine tells me Chess Truth
Reply #81 - 02/12/12 at 17:28:44
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I don't know what engines say about this position...but I can easily guess.  Wink

* * * * * * * *
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*

FEN: 8/8/8/1k1p2p1/p2P2P1/P3P3/qPKN4/8 w - - 0 1

Why all these silicon beasts don't understand chess fortresses at all?
Huh
  
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Re: My trusty engine tells me Chess Truth
Reply #80 - 02/09/12 at 16:31:47
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[quote author=47796D67787B624B52757A140 link=1319957182/75#75 date=1328716119]Vladimir, the goalposts are, can a human work out that only Bh3 wins while a computer can't?
[/quote]

I guess 99% of the human players wouldn't even consider ...Bh3, unless they've seen the idea before.

The machines are getting better and better, but sometimes they can still show a remarkable [i]lack of common sense[/i]. For example, I recently made some engines play an unusual opening idea to get some more practical examples. Unfortunately, all the games played were useless, as in the structure f5,e6,d7,c5,b7 with a Bc8 present, none of them ever got around to let Bc8 out! :))

So, many of the games became examples of middlegames/endings with a white c5-pawn almost single-handedly holding down d7, Bc8 and b7 until black eventually caved in.

Here, in similar situations, I'm sure 99% of the human players would find the time to let the bishop out with d6 or b6 long before a white c5-pawn appears...
  
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Re: My trusty engine tells me Chess Truth
Reply #79 - 02/08/12 at 18:45:13
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...As some say on a computer chess forum which member I am: "The stars were shining properly when the move was found."   Grin
  
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Re: My trusty engine tells me Chess Truth
Reply #78 - 02/08/12 at 17:58:43
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Smyslov_Fan wrote on 02/08/12 at 15:48:39:
Vladimir, the goalposts are, can a human work out that only Bh3 wins while a computer can't?

You say that the computer sees Bh3 as winning and no other move is quite sufficient to win. I'd accept that if it reproducible. The computer can't have had Bh3 already played though.

As I said, the goalposts seem to have moved because everyone was previously wondering if computers could even find the move, like the very quote I prefaced my first post with. And amidst all of this incredulity, did either of you look at the two links provided? Several engines find 47...Bh3 in reasonable time.  Huh Notably, though, Stockfish seems to fail at finding the move.

Here is Houdini 1.5a, with the score still going up and up on the 29th ply before I decided to finally terminate the search. Note that Houdini doesn't really show its periodic score increments on separate lines like Critter does, so the final line's +5.60 is only after several smaller increases were displayed during the search:

Code
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Houdini_15a_x64:

 26/54	00:49	 553,861,944	11,081,000	+1.48	Bf5-e4 g2-g3 f6-f5 Kg1-f2 Ke6-d6 Bc3-d4 Kd6-c6 Kf2-e2 Kc6-b5 Ke2-d2 Kb5-c4 Bd4-b2 d5-d4 Kd2-e2 d4-d3+ Ke2-d2 Kc4-b3 Bb2-a1 a4-a3 Ba1-c3 a3-a2 Bc3-h8 Kb3-c4 Kd2-e3 Be4-f3 Ke3-d2 Bf3-d5 Bh8-c3 Bd5-b7 Bc3-a1 Bb7-e4 Kd2-c1 Be4-a8 Kc1-d2 Ba8-d5 Kd2-e3 Bd5-e4 Ke3-d2 Be4-f3 Kd2-e3 Bf3-h5 Ba1-e5 Bh5-g4 Ke3-d2 Bg4-e2 Be5-c3 Be2-h5 Bc3-b2 Bh5-g4 Bb2-a1 Bg4-e2 Ba1-c3 Be2-h5
 27/54	01:02	 694,243,666	11,165,000	+1.48	Bf5-e4 g2-g3 f6-f5 Kg1-f2 Ke6-d6 Bc3-d4 Kd6-c6 Kf2-e2 Kc6-b5 Ke2-d2 Kb5-c4 Bd4-b2 d5-d4 Kd2-e2 d4-d3+ Ke2-d2 Kc4-b3 Bb2-a1 a4-a3 Ba1-c3 a3-a2 Bc3-h8 Kb3-c4 Kd2-e3 Be4-f3 Ke3-d2 Bf3-d5 Bh8-c3 Bd5-e4 Bc3-f6 Kc4-b3 Bf6-e5 Kb3-c4 Kd2-c1 Kc4-d5 Be5-a1 Be4-f3 Kc1-d2 Kd5-c4 Kd2-e3 Bf3-h5 Ba1-e5 Bh5-g4 Ke3-d2 Bg4-e2 Be5-c3 Be2-h5 Bc3-b2 Bh5-g4 Bb2-a1 Bg4-e2 Ba1-c3 Be2-h5
 28/54	01:22	 929,349,860	11,264,000	+1.48	Bf5-e4 g2-g3 f6-f5 Kg1-f2 Ke6-d6 Bc3-d4 Kd6-c6 Kf2-e2 Kc6-b5 Ke2-d2 Kb5-c4 Bd4-b2 d5-d4 Kd2-e2 d4-d3+ Ke2-d2 Kc4-b3 Bb2-a1 a4-a3 Ba1-c3 a3-a2 Bc3-h8 Kb3-c4 Kd2-e3 Be4-f3 Ke3-d2 Bf3-d5 Bh8-c3 Bd5-e4 Bc3-f6 Be4-c6 Bf6-a1 Bc6-b7 Kd2-e3 Bb7-d5 Ba1-h8 Bd5-e4 Ke3-d2 Be4-b7 Bh8-a1 Bb7-e4 Kd2-c1 Be4-a8 Kc1-d2 Ba8-d5 Kd2-e3 Bd5-e4 Ke3-d2 Be4-f3 Kd2-e3 Bf3-h5 Ba1-e5 Bh5-g4 Ke3-d2 Bg4-e2 Be5-c3 Be2-h5 Bc3-b2 Bh5-g4 Bb2-a1 Bg4-e2 Ba1-c3 Be2-h5
 29/63	01:57	1,338,366,562	11,349,000	+1.48	Bf5-e4 g2-g3 f6-f5 Kg1-f2 Ke6-d6 Bc3-d4 Kd6-c6 Kf2-e2 Kc6-b5 Ke2-d2 Kb5-c4 Bd4-b2 d5-d4 Kd2-e2 d4-d3+ Ke2-d2 Kc4-b3 Bb2-a1 a4-a3 Ba1-c3 a3-a2 Bc3-h8 Kb3-c4 Kd2-e3 Be4-f3 Ke3-d2 Bf3-d5 Bh8-c3 Bd5-e4 Bc3-f6 Kc4-b4 Kd2-c1 Kb4-b3 Bf6-a1 Kb3-b4 Kc1-d2 Kb4-c4 Kd2-c1 Be4-a8 Kc1-d2 Ba8-d5 Kd2-e3 Bd5-e4 Ke3-d2 Be4-f3 Kd2-e3 Bf3-h5 Ba1-e5 Bh5-g4 Ke3-d2 Bg4-e2 Be5-c3 Be2-h5 Bc3-b2 Bh5-e2 Bb2-a1 Be2-f3 Kd2-e3
 29/64+	03:07	2,134,991,667	11,382,000	+1.56	Bf5-h3
 29/78+	13:15	9,214,503,132	11,583,000	+5.60	Bf5-h3



Here is Critter 1.4 with the session file disabled and deleted just in case. Similar to Houdini, the score kept rising on the 28th ply before I terminated the search.

Code
Select All
Critter_1.4_64bit_sse4:

 26/49	00:43	 446,703,523	10,260,790	+1.95	Bf5-e4 g2-g3 f6-f5 Kg1-f2 Ke6-d6 Bc3-b4+ Kd6-c6 Kf2-e2 Kc6-b5 Bb4-e7 Kb5-c4 Ke2-d2 d5-d4 Kd2-c1 Kc4-b3 Be7-f6 d4-d3 Kc1-d2 a4-a3 Bf6-c3 Kb3-c4 Bc3-e5 a3-a2 Be5-a1 Be4-f3 Ba1-f6 Bf3-a8 Bf6-c3 Ba8-d5 Bc3-a1 Bd5-e4 Ba1-c3 Be4-f3 Bc3-a1 Bf3-a8 Ba1-c3
 27/49	01:05	 665,685,130	10,161,890	+1.95	Bf5-e4 g2-g3 f6-f5 Kg1-f2 Ke6-d6 Bc3-b4+ Kd6-c6 Kf2-e2 Kc6-b5 Bb4-e7 Kb5-c4 Ke2-d2 d5-d4 Kd2-c1 Kc4-b3 Be7-f6 d4-d3 Kc1-d2 a4-a3 Bf6-c3 Kb3-c4 Bc3-e5 a3-a2 Be5-a1 Be4-f3 Ba1-f6 Bf3-a8 Bf6-c3 Ba8-d5 Bc3-a1 Bd5-e4 Ba1-c3 Be4-f3 Bc3-a1 Bf3-a8 Ba1-c3
 28/49	01:41	1,045,130,803	10,351,724	+1.95	Bf5-e4 g2-g3 f6-f5 Kg1-f2 Ke6-d6 Bc3-b4+ Kd6-c6 Kf2-e2 Kc6-b5 Bb4-e7 Kb5-c4 Ke2-d2 d5-d4 Kd2-c1 Kc4-b3 Be7-f6 d4-d3 Kc1-d2 a4-a3 Bf6-c3 Kb3-c4 Bc3-e5 a3-a2 Be5-a1 Be4-f3 Ba1-f6 Bf3-a8 Bf6-c3 Ba8-d5 Bc3-a1 Bd5-e4 Kd2-c1 Be4-f3 Kc1-d2 Bf3-a8 Ba1-c3
 28/66+	03:17	2,124,799,077	10,784,796	+2.07	Bf5-h3 g2xh3 Ke6-f5 Kg1-f2 Kf5-e4 Bc3-b2 f6-f5 Kf2-e2 f5-f4 Bb2-c1 f4-f3+ Ke2-d2 d5-d4 Bc1-a3 d4-d3 Kd2-e1 Ke4-d5 Ba3-b2 Kd5-c4 Bb2-c1 Kc4-c3 h4-h5 g6xh5 h3-h4 Kc3-c2 Bc1-d2 a4-a3
 28/71+	04:34	3,012,321,706	11,002,990	+2.37	Bf5-h3 g2xh3 Ke6-f5 Kg1-f2 Kf5-e4 Bc3-b2 f6-f5 Kf2-e2 f5-f4 Bb2-c1 f4-f3+ Ke2-d2 d5-d4 Bc1-a3 d4-d3 Kd2-e1 Ke4-d5 Ba3-b2 Kd5-c4 Bb2-c1 Kc4-c3 h4-h5 g6xh5 h3-h4 Kc3-c2 Bc1-d2 a4-a3
 28/74+	06:01	4,023,197,764	11,136,910	+2.64	Bf5-h3 g2xh3 Ke6-f5 Kg1-f2 Kf5-e4 Bc3-b2 f6-f5 Kf2-e2 f5-f4 Bb2-c1 f4-f3+ Ke2-d2 d5-d4 Bc1-a3 d4-d3 Kd2-e1 Ke4-d5 h4-h5 g6xh5 h3-h4 Kd5-d4 Ba3-e7 Kd4-c4 Be7-d6 Kc4-b3 Bd6-c5 Kb3-c3 Ke1-d1 Kc3-c4 Bc5-f2 a4-a3 Kd1-d2 a3-a2
 28/74+	08:50	5,995,119,336	11,307,534	+3.05	Bf5-h3 g2xh3 Ke6-f5 Kg1-f2 Kf5-e4 Bc3-b2 f6-f5 Kf2-e2 f5-f4 Bb2-c1 f4-f3+ Ke2-d2 d5-d4 Bc1-a3 d4-d3 Kd2-e1 Ke4-d5 h4-h5 g6xh5 h3-h4 Kd5-d4 Ba3-e7 Kd4-c4 Be7-a3 Kc4-b3 Ba3-c5 Kb3-c3 Ke1-d1 Kc3-c4 Bc5-b6 a4-a3 Kd1-d2 a3-a2
 28/74+	14:32	10,021,279,498	11,493,228	+3.65	Bf5-h3 g2xh3 Ke6-f5 Kg1-f2 Kf5-e4 Bc3-b2 f6-f5 Kf2-e2 f5-f4 Bb2-c1 f4-f3+ Ke2-d2 d5-d4 Bc1-a3 d4-d3 Kd2-e1 Ke4-d5 h4-h5 g6xh5 Ba3-b2 Kd5-e4 Bb2-g7 Ke4-e3 Bg7-h6+ Ke3-d4 Ke1-d2 a4-a3 Bh6-g7+ Kd4-e4 Kd2-e1 a3-a2 Bg7-f6 Ke4-e3 Bf6-g5+ Ke3-d4 Bg5-f6+ Kd4-c4 Bf6-a1 h5-h4 Ba1-f6 Kc4-d5 Bf6-g7 Kd5-e4 Bg7-f6 Ke4-e3 Bf6-g5+ Ke3-d4 Bg5-f6+ Kd4-e4 Bf6-g7 Ke4-e3 Bg7-h6+ Ke3-d4 Bh6-g7+ Kd4-e4


Trw, SMP searches are non-deterministic. That means that exact times are not reproducible, and that separate runs could find the move faster or slower than before, and even on different depths. For example, if I run through them again, they could find the move after 5 minutes, or get lucky and find it in under 3. Or maybe they find the solution faster without the slowdown from tablebases, who knows.
  
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Re: My trusty engine tells me Chess Truth
Reply #77 - 02/08/12 at 17:43:16
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At depth 32, Houdini also failed to find Bh3. But to Houdini's credit, it didn't think Be4 and a3 were 'winning' just slightly better. at 1.32 and 1.23
  
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