# Positions engines get wrong ( please contribute )

• #61
This position comes from the end of an interesting puzzle. Insert this setup into your favorite engine. The position is a dead draw, but engines will give black something around -14. White only needs to move the bishop along the a7-g1 diagonal and there is nothing black can do to win.
• #62

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.

• #63

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.

• #64

• #65
wickiwacky wrote:

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.

• #66

IM Marc Esserman's book Mayhem in the Morra is filled with positions where the engines give erroneous evaluations.

• #67
pfren wrote:
wickiwacky wrote:

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.

Crikey yes! Missed the stalemate at the end - the f2 pawn just ready to Queen and cant do it.

• #68
AndrejPro wrote:

truly interesting piece!

thx for sharing this

• #69
pfren wrote:

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?

• #70
[COMMENT DELETED]
• #71
pfren wrote:

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.

My engine said that Rb6 is best and Rc6 is a blunder...

• #72

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.

• #73
Trevor-D wrote:
pfren wrote:

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?

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.

• #74

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.

• #75

@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.

• #76
I once tried using to engines .Making one vs the other one but later blundered like this
1.d4 1. ...e5
or

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