Mate in two(41)

White in two    by   A.F. Rudolf,    1911

This is a wonderful composition and I can't see any flaw in it. Is there one?

Here is an alternative setting. Not to solve a flaw because I couldn't find one but to raise the profile of Na3 by moving it to a more active spot. What is lost, is the nice black promotion on e1.

The author marks puzzles that are (he thinks) exceptional regardless of their aesthetic defects. Usually he has a few words about the defect,he only has praise for this one,but it is marked. Could it be a piece proved to be from a promotion....I personally don't think legal position should be such a big issue since how the positions arrived at in these puzzles would never have happened anyway.

No promotion pieces, no unprotected checks, no flight square taken and the white king gives the maximum number of unique discovered checkmates (6). The zugzwang is perfect, for instance leading to the queen checkmate moves Qd4, Qe4, Qf4, Qc3, Qb2, Qa5, Qb5, Qc5, Qd6, Qe7, Qb8, Qe1. What is missing are realistic tries and set play but it's not something the author tried to achieve, given the heavy duty of realizing all the discovered checkmates. Though one try might be nice. But I can't find a reason to mark this problem down. May be Rocky64 can. He is also a specialist.

By the way, here is a version with a thematic try but I wouldn't call it superior to the other versions:

Maybe it was a mistake on his part. there was a cooked puzzle which I found out when I posted it on here #523 Hard to believe it was missed by so many people.

Rudolf's problem is marked as an "exceptional record" in Morse's book because it combines two maximum tasks: 12 WQ mates and 6 WK mates. These mates are of course all forced individually in the main variations, e.g. 1...Qh6+ 2.Kxh6, but there are many duals after some "weak" black moves, e.g. 1...Qxg4 even allows 3 white king mating moves. I think this is a flaw, especially since the duals involve the thematic mates.

Incidentally, Morse made a good rendition of the 12 WQ mates idea himself. It doesn't have the 6 WK mates but it's completely dual-free. It's quoted as No.4 in my blog, An introduction to composed chess problems.

Thanks, Rocky64! I noticed the weak "defenses" in addition to the 12 Q-checkmates and 6 discovered K-checkmates. As you mentioned, there are unique variations for all of them. The weak moves (like ...Qg4) only show up because it is a zugzwang problem. The difference between this problem and many zugzwang problems is that zugzwang is not part of the theme here but only the means to an end. If zz were a thematic ingredient then it would be natural to treat every counter move as a thematic defense against zz, requiring a unique reply. In my view, this problem shouldn't receive the credits of a genuine zz problem, neither should it be criticized and marked down for not being a perfect zz problem. But it is a perfect record realization of the K+Q checkmate theme!

Too easy

@Aristotle Yeah, I agree the duals aren't that important. The problem would be clearer without them, but the double tasks it shows is such an achievement that these duals are easily forgiven.

I myself have composed a task problem with a worse sin - unprovided checks!  

Thanks for the input Rocky and Arisktotle   I will post some more exceptional with a blemish puzzles from his book...