Questionable puzzle

nah, #9 is right.

You have mate in one on the board, if you don't play it, it's a horrible blunder no matter what. If you're up three queens, it's still irrelevant.

It's a different story if you have mate in 2 and mate in 3 (starting with a different move). Now, that's an alternative solution.

@sgtlaugh said in #10:
> The initial eval for Qxd4 is not so high however. I didn't check with higher depths. But algorithmically probably this is why this puzzle was not discarded. If it were to be evaluated as +5, I doubt this puzzle would make it even after having mate in 1.

I think this is a fair assessment. I think the engine started at around +1.5 or something like that. If the engine needs a couple of seconds to go to +5... this is usually not an automatic win for humans on lower levels.

Of course one can discuss if we want puzzles with a true unique solution in a mathematical sense - and I can easily argue for both sides. :-)

@nadjarostowa said in #12:
> this is usually not an automatic win for humans on lower levels

This is also important point, IMHO. The puzzle has rating ~1000, IIRC, which should give us a hint about who is likely going to meet it.