Positions engines get wrong ( please contribute )

In the thread about the match between Anand and Carlsen has fabelhaft posted this combination of Magnus Carlsen:

http://www.chessgames.com/perl/chessgame?gid=1268980

He told that even Houdini did not see the final combination.

"When the computer sees forced moves, it plays like God"-Garry Kasparov

@watcha: Reducing the 50 move-rule in the config of Houdini of course is not a good idea. Houdini should be able to find the mate in 30 when there's only 4 pieces left as this should limit the search-tree far enough to look deep enough. It doesn't give any benefit to it's playing strength anyways. It simply makes it call a drawn position drawn quicker at the expense of more possible "false positives" in that regard.

The forced mate in 261 is particularly funny. Only tablebases will "know" that... and engines that use tablebases. But then again it doesn't work anyways because of the 50 move-rule.

Shirov's Bh3 is an excellent move, but I don't understand why Topalov took the bait. Would he not be still in the game after simply g3 in response?

I see a whole array of openings and endgames that no computer seems to get right.

Computers think the King's Indian, Grunfeld, and Benoni are all at least three quarters of a pawn better for White by move 8 or so.

Endings are always a joke.  R+N vs R, no pawns, they'll say is +3.  Another good example of one that computers always think is winning is White has a Queen, Black has a Rook and Pawn.  The pawn protects the Rook.  The King is guarding the pawn.  White's King is on the wrong side of the Rook (for example, if the Black Rook is on d5, White's King is on the 1st thru 4th ranks, not the 6th thru 8th ranks).  Computers always think White's winning.  Any human ought to know that KQ vs KRP with the K, R, and P all united and the WK on the wrong side of the Rook is an easy draw as the Black Rook merely toggles on the two squares that the pawn protects except when White checks with the Queen.

The idea was to get a tempo to play Kf5....e4 so the white king must defend g2 or play g3. If bb1 for example then kf2 to ke3 defends in to

A computer said this was a draw.  After annotating a certain game I flipped on the engine and was kind of confused when it said draw when I calculated a win for white:

Till now we had been looking for positions, now I have a game .

I found this game from this thread: http://www.chess.com/forum/view/general/houdini-4-released-but-the-arb-chess-system-still-crushes-it

The person claims to beat today's strongest chess engines by a specific opening(or rather gameplay).

In this game he claims to have beaten Houdini 4 (a new release which is a lot stronger than Houdini 3), but I doubt about it, as this game was played 4 months ago while it has been just a few weeks since Houdini 4 was released.

I haven't analysed this game with any engine but it would be interesting to know the result if someone analyses it.

TheGreatOogieBoogie, what engine are you using?

Wow, that's an interesting endgame.  It's refreshing to see your post with evidence that engines pick the wrong moves (not just misevaluate the position but also throw away the win).

This game has been analyzed at length in the thread http://www.chess.com/forum/view/general/houdini-chess-program-crushed---using-the-arb-chess-system.

I have checked this game and it seems authentic. Given the time control ( 1 minute / 1 move ) it is very plausible that Houdini could have missed the winning (sacrifice) move on move 19. In single PV mode I have tested this move several times starting Houdini with empty hash and on many occasions finding the correct move took significantly longer than 1 minute if it was found at all. In multi PV mode the correct move was found much quicker.

Finding sacrifical moves is not easy for engines ( there are many examples of this on these forums ). Theoretically you can always raise the multi PV limit to the point that all legal moves are getting analyzed in which case the merits of the sacrifice move may be quickly found. However this is impracticable since it decreases the overall strength of the engine dramatically.

Jeez I can never get enough of posting this position:

Maybe sacrificing some king safety for chances to get rid of the darksquared bishop (both his most important defender and attacker) and restricting c5 wasn't worth it?  If I played h3-Bh5-g4-Bg6-Bxg6-fxg6 I'd have a clear advantage but tunnel visioned on restricting c5. 

Both Stockfish (+0.5) and Houdini (+0.35) see this position slightly better for white ( assuming that it is white's turn - which is not indicated in the diagram ). In what way is this position considered an engine failure?

Maybe we have different processors or different versions?  I set Stockfish to 95 value for space (overrated since practically cramped positions contain latent resources.  I say "practically" because players are looking for their best move so wouldn't accept a cramped position without compensation or a punching out plan)  95 pawn structure (middlegame) and 105 activity and bishop pair so maybe that swayed the eval? 

I've got a game which shows how differently programmed chess engines are.

Houdini 3 found out after 37 seconds that Nc7 was the best move.After 45 secs. it found that it was actually the winning move.

Rybka 3(not 4) after 18 secs. gave Nc7 top priority and after 1:44 realised that it was actually the winning one.

Bad luck was with Stockfish 4 64 bit SSE4.2 who even after 13 minutes couldn't realise that Nc7 was the best.I stopped it after that.

I hope someone would make stockfish find the truth even if it takes half an hour(or more).If it isn't able to find the winning move then it would be a real failure for Stockfish programmers.

NOTE:For all the tests I used the single PV mode ONLY.

For me Houdini found out 24. ... Nc7 in 57 secs and immediately as a winning move. Rybka found it in 17 secs and made it a winning move after 1 min 6 secs. I finished analyzing with Stockfish after 3 mins 53 secs without finding the move. These were all in single PV mode. So basically I can confirm your results.

I'm always surprised what positions the big Rybka 4 book contains. Once I have run into a mate puzzle in one of the threads the solution of which was a recommended move in the Rybka 4 book. Believe ot or not your position is also represented in the Rybka 4 book with 24. ... Nc7 as a green ( recommended ) move:

Are you saying that Rybka 4 opening book contains the information?

Stockfish is known to be pruning a lot more aggressively in order to go much deeper on what it thinks are good continuations.

The downside of this is, as we've just seen here, that it often won't find winning sacrifices.

houdini and shredder is the best