FREE - In Google Play
FREE - in Win Phone Store
AndrejPro - I disagree - that position is a win for black. The Queeen goes to a1 - e5 - e1 and then f2 where white is forced to accept the sac and thus loses.
When this happens, white takes the queen, and after ...gxf2 he plays the only legal move, g2-g3+. Stalemate, regardless if Black captures, or plays ...Kh3.
IM Marc Esserman's book Mayhem in the Morra is filled with positions where the engines give erroneous evaluations.
Crikey yes! Missed the stalemate at the end - the f2 pawn just ready to Queen and cant do it.
truly interesting piece!
thx for sharing this
Here is a correspondence game I played (this means both players could use an engine). Black played 35...Rc6, which is the recommendation of all engines. An engine can calculate that white loses the pawn back if he exchanges rooks. What an engine cannot calculate within a reasonable timeframe is that the resulting king and pawn endgame (with equal pawns) is completely lost for Black (horizon effect), while an average human player will realize this after less than two minutes' thought.
So is there a move for Black which doesn't lose?
My engine said that Rb6 is best and Rc6 is a blunder...
In this famous position, Stockfish recommends a3, while if d4 is played, black's much, much better, even according to Stockfish. I don't understand why it can't see that.
Rb6 probably loses as well (white has a healthy extra pawn), but Black can fight for a while. After Rc6 everyting is forced- and Black loses.
In the famous game Short-Timman, White marches his king into Black's castled position and mates him in the middlegame. When I try Stockfish on this game, it does not like the first two moves of the king march, and will in fact recommend moving the king *back* if you force it to play the first. It's really interesting to see it claim to be looking 17+ moves ahead when it is missing a mate in 5. After the second king move it suddenly sees the mate.
I haven't let it run for hours, admittedly, but I think it is looking further and further ahead, and has already ruled out the winning line so will probably never find it.
It is amazing that a human found this: it's probably the most implausible combination I've ever seen.
@mkkuhner: That's a very nice one by Short. Indeed -- on move 34 Stockfish evaluates the position as equal and recommends the push of pawn to c3, after which the evaluation doesn't change. Instead, in the game Kf4 is played and Stockfish evaluates the position as +8.4. A similar scenario to the Topalov vs Shirov game.
yeah, I am learning by evaluating what the 2 computers did, but who knew it made a blunder.
I remember a Stockfish vs Komodo game someone posted on some other forum. There Komodo thought its position was better, two moves before getting completely demolished - two moves later, its evaluation switched from ~+0.8 to -5 or something like that. The position also looked completely won by white, black was tightly squeezed, his king was in a huge danger, and there was no apparent reason for Komodo to think it was better. My guess is, Stockfish simply out-calculated Komodo, and Komodo saw the line it initially dismissed or didn't calculate far enough.
I have a question about all of these difficult positions: is there any pattern that could be identified? I am doing a doctoral course, and my thesis is about pattern recognition . As a general concept of a pattern we assume as being: a subset of relationships (attacks/defenses, direct/indirect) between pieces plus a set of initial conditions plus a tactical move plan plus a set of post conditions (e.g. Philidor's mate). I created a language to represent such patterns that could be used to some way retrieve better/worst values when machine are evaluating such positions.
@lcfb2003: there is not a particular pattern between those examples, but I think that there is a statistical relationship between them: they all occur very rare.
Take for instance this pearl from Nezhmethdinov:
Who would ever think of this queen sacrifice at move 12? It takes a genius to find it.
@LoekBergman Thanks. Another question: in this example you posted, in terms of future scenario the player was aiming to reach, should it be explained some way as a pattern or a collection of features?
This position was published in a French magazine in 1912, and then appeared in Hans Kmoch, Pawn Power in Chess. I set it up and played it against Stockfish 7. The computer thought it had an overwhelming advantage until it declared a draw by the fifty move rule.