The most beautiful puzzle that my engine can never solve

Post #16 is a mate in 26 (or less):

Here is another study where Stockfish is absolutely helpless (along with other engines), and has no clue as to the solution:

White to play and WIN:

"Can't solve" seems to be a bit of an overstatement. In my test Stockfish finds all the correct moves for white but takes until a few moves in to realize white is winning. One can then back it up to the start and it will "remember" that it has a winning position (in its evaluation.)

Given a long enough think time, or fast enough hardware, I think it would evaluate white as winning from the start.

[edit] also props to the OP for finding a sort of click baitee title to boost engagement: "engine can never solve"

nice puzzle

Hi i got check mate and the computer told me it was the wrong move so idk if it is such a bad puzzle

i meant to write beautifull instead of bad sorry

After the 7th move ke3

Well of course if you feed Stockfish the moves it will eventually see that white is winning, but Stockfish WILL not see the second move (2.Qxc7+!) on any hardware, it DOES NOT see the Queen sac on the second move at the square c7. I have a 20 core machine and it doesn't find the second move even if I let it think in infinite mode for several hours.

Here is Stockfish 16 after 2 hours trying to find the second move using 20 threads and a 16GB hash table, and still no dice showing a draw score of 0.00 after 214 billion nodes searched:

That's not what I did. I put Stockfish into analysis mode and then played its moves as white against your solution moves as black, and it found Qxc7+. It still evaluated 0.00 until some moves down the road when it decided white was winning, and then when I backed it up to the beginning it maintained that white was winning all along.

I was not able to replicate it when I tried it again today, so I'm not sure what happened there.

One thing I'd say on a more meta level though is that of course Stockfish can solve this. Any engine can solve this. It's just a matter of the horizon effect, not a fundamental incapability.

Well, you'll have to forgive me if I'm a bit skeptical about Stockfish finding 2.Qxc7+! because it has NEVER found it on my 20 core system, also when you "back it up" the correct moves and evaluation are stored in the hash table so of course it's going to see that white is winning, and I maintain that Stockfish cannot solve this no matter what the horizon.

Here's another one it can't solve:

No I know why the cheaters in puzzles don't get 100%^^

These engines could not solve the puzzle , to explain it professionally , just because there are not updated the programs which have ability to trapp queen and use zugwang to win material . To update this program , need lots of money and energy , that is why the vast majority of engines currently do not have this program installed . Of course , these engines can't solve the puzzle .

Make sure that most of cheaters can't get his first move correctly in these types of puzzle .

If there are puzzles that engines just fundamentally cannot solve, and the limitation is not due to the Horizon Effect, then it seems likely there should be some unsolvable puzzles where the solution doesn't run 40 or 60 ply deep. Any 10 ply examples?

The limitation is always due to the Horizon effect. Having accepted that fact, the designers of engine software have added heuristic and neural network strategies which are inherently imperfect. But even the simplest engine software could solve every chess puzzle by backward induction if not restricted by the speed of its CPU cores - what we know as Horizon.

Try this Mate in 5 that Stockfish struggles with, and remember this isn't white to play and win, it is a mate in 5 (not a mate in 22 or 15 or 7):

I believe the Stockfish algorithms would, in principle, play perfect chess given unlimited computing and memory. This is because if it continued to grow the analysis tree, eventually it would be complete, and its choice would be game theoretic optimal. This is impossible in practice because of the vast time and memory needed.

Correct Mark, but Stockfish 16 doesn't see it (most people don't get the developement versions) and I doubt that Dragon does either even though I don't own it, and the guy I was giving this position to asked for a 10 ply that engines like Stockfish won't solve rather than a mate finder that can't play a game of chess like WinCHEST (unless of course some day it finds a forced mate from the starting position , which if the game is a draw from the starting position then that would be impossible).

I edited mine to read Stockfish 16 doesn't solve it.