white to move, m1

Ah, you didn't get my explanation of mathematical models at all! A model is precisely the opposite of what you believe. There are no hidden system rules only choice rules or "possible worlds (games)". A problem with the Qa8-a0 solution is only possible in language form, but not in the reality of a legal chess game for the diagram. It is not a possible world. For the solutions to both M1 problems, proof games exist played exactly by the game rules as you know them. The choice rules concerned are also standard and widely known so they are no joke problems.

Note: The choice rules of math are found in the conventions of chess compositions. Playing games is fundamentally different from solving problems in the sense that history information is missing which is commonly known in games (even mandatory for arbitrations). They also prevent unwanted contradictions, like a poster insists "white is on move" while analysis reveals that such is impossible in all proof games. Note that even the FIDE laws state that a position should be legal. It's not only composition folks!

Indeed, I don't know what the difference is between what you call "hidden rule" and choice rule". To you, the hidden 0th rank is the former, and the rule that there must be a legal proof game from the standard position is the latter. To me, these two are indistinguishable.

The two are very easily and objectively distinguishable as further explained in my last post. It's pure science and way beyond the common misconception on social media that everything is personal opinion. 

Another observation. The game of chess is deterministic (all game options are predefined) but chess puzzles/compositions are not. There is a blank space which can be filled at will within boundaries. One can vary the conventions without contradicting the chess rules - e.g. if one prefers no castling right (except when provable) for a puzzle, it can be done. Not only is it not illegal, it is not a joke either. It only requires communication. Puzzling without choice rules is impossible as you can't decide on a solution if you can't decide on your legal move options.

Chess players have a mind bent towards determinism or they would have chosen ballet rather than chess. They get worried, get weird dreams and go mad when confronted with nondeterministic issues which are however flourishing in science and in the real world. The field of logic largely targets nondeterministic environments as the deterministic ones are kind of simple and boring.

Yes the rule is hidden, but it's not impossible to solve with the information given... if the only information you're given is it's mate in 1 then you have enough information to uncover the hidden idea and solve the puzzles using nothing but the standard rules of chess.

In your example of hidden squares that's not the standard rules of chess.

The main problem when encountering positions like this on the forum is you get a lot of beginners posting nonsense puzzles, so there's no reason to trust the information is correct (mate in 1). But if you're able to trust that information, and that a solution exists, then it's possible to solve both of them.

I usually understand what you (Arisktotle) are saying, but now I don't. Your last 3 posts are total gibberish to me. So let's leave it at that.

That's OK. You'll carry that weight thru your puzzling career. Even though other people will use more mundane language, there is no way around the proper understanding of puzzles with retrograde aspects.

What's the solution,  its impossible

The puzzle is intentionally deceptive. Blacks last move was g5, so white can play hxg6# with en passant.

Are there "hidden rules" in chess composition?
This article would be a good introduction.

https://www.theproblemist.org/beginner.pl?type=b_int

There are "rules" for chess compositions but they are not hidden. They are the bible for everyone involved in compositions - as composers, solvers or organizers. They are as diverse as the FIDE rules in that they include formats for compositions, publications, competitions and composition types. They are governed by the WFCC - the World Federation for Chess Compositions - which is independent of FIDE which governs the chess game rules and activities. Since their legal separation FIDE and WFCC work happily together! Most countries have clubs of problemists which organize meetings and events like solving competitions.

https://www.janko.at/Retros/Glossary/Codex2015.htm

1. Qa0 !? Ki6!!

Just saw your link to the "Problemist", a place where some of my own compositions were published. Good stuff on the content of a composition. The Composition Codex gives a comprehensive overview of all activities and rules relating to "compositions". Like your text is immediately recognizable as the solution to a fairy composition

Bro I haven't found any mate in one. But there are sorts of mate in 2 ,3 more. Of course the king has been stock. There must be so many mates but not in one

en passant

There is - but don't ask your engine. It does not know.

When the gas triples in price it is way to simple for the whole world to get stuck on, but it does.

Or, as Tarrasch would have put it, "the significance of a move lies not in its appearance but in the thought behind it". Or was that Nimzowitch?

The OP puzzle is not M1, confirmed with analysis. I left off the lines so there are no spoilers:

en passant has joined the chat

This puzzle is about being creative. Think what your opponent's last move is.

idk, hxg6# e.p.?