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Stockfish Level 7 misses a mate in one

Take a look at the following game between Stockfish Level 7 and my bot:



Stockfish simply needs to play 31. Qb7# but it fumbles around for a while by giving a few checks, capturing a rook, and then finally mating with the c-pawn.

I would expect that, given that Stockfish Level 7 has an estimated (or approximate) elo of 2200, that it would not miss this simple mate in one. Any idea on what could cause this?
I wouldn't call that "missing a mate in one", that's somehow misleading. The computer is in no worse position after "missing" it. You don't get more points when you mate in less moves. You win, draw or lose.

So after finding a mating pattern, it's energy saving when the computer stops calculating :P

I approve that behavior.
I suppose you are right -- it didn't lose a forced checkmate sequence -- but it did take the longer route.

What confused me initially is that if you click on the "Move Times" tab, it says the computer spent 5.6 seconds before making the move 31. Qb5+, but if it had already calculated a forced checkmate sequence, it wouldn't need to spend 5.6 seconds calculating that move. But perhaps there is some "fake thinking time" added here, and in actuality it might have not calculated anything at all.

Haha lol... indeed the 5.6 seconds look strange.

I mean in the end who knows, maybe the software did some weird computations and is buggy. Maybe the operating system is buggy and was trapped a couple of seconds handling some interrupts. Maybe the inet had some lag.
Oh does the computer not play at full strength (stockfish on level 7)? Then it can be on purpose to waste time and play suboptimal moves, no?
I am not sure, but maybe all of those are possibilities.

It's the second strongest level of Stockfish available on Lichess, so while it won't be at full strength, I would have expected it to play optimally in such a scenario. I think your earlier explanation about it halting computation after finding a forced checkmate sequence is likely correct :p

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