Know the rules of chess! Very tricky endgame puzzle

Enjoy this tough one!

Technically, since there are legal methods of reaching this position with the king and rook moving prior to the start of the problem, casting rights need to be specified to give the solver a fair chance of correctly solving what appears to be a dead drawn composition. Unfortunately, that ruins the brilliance of the answer.

I knew immediately that the solution would involve castling queenside but the only question was when. Perhaps a bonus question for people to answer would be to explain why O-O-O immediately fails to win.  

hehehe. It is so evil this puzzle. Like an en passant puzzle on the chess.com tactics trainer

Actually, castling permissions (unlike e.p. permissions) need not be specified because they are a default assumption in all regular chess compositions. So contrary to the OP's intention this puzzle is not evil but simply OK.

Very nice!

Thanks for this!

Solved!

Tricky, but fun!

Thanks :-)

Why are casting rights a default assumption but not en passant rights?

The choices are fundamentally arbitrary but reflect the events and attitudes in actual chess games. Generally players try to preserve castling rights as an option to activate when called for. So it seems fair to assume this is the case when a king and rook are in original K/R positions. En passant opportunities arise haphazardly and only have single move longevity. Not enough justification to reward a default e.p. permission.

By the way it is possible to invoke the inverse conventions if you want to but it is not all that common. I recently made a double inverted e.p. problem where the convention was inverted but the solving instruction was inverted again such that you had to prove that there was no-e.p.-right after all. We are quite flexible in the retro-field :-)

Thanks for the explanation! Do you mind sharing the double inverted en passant problem?

I wouldn't mind to show it but explaining it would require a long story. The inverse part is relatively simple but the inverse-inverse is based on AP-logic which is not even familiar to most retrograde experts. Recently had to explain it to a leading retrograde specialist. Here is a link to an example. You want to go that way?

https://en.wikipedia.org/wiki/Retrograde_analysis (last diagram)

It's a rather complicated example but with a bit of comment to explain the mechanism. The idea is that you first play the e.p. move and justify it later by castling because (in the diagram) castling right provably implies e.p. right. We know this as "T-Rump logic". First you claim your election was stolen from you without proof, only then you start looking for evidence to back up your position. Chances are you fall flat on your face!

Is it fair to claim those retrograde analysis problems involving posteriori convention are to be approached from a problemist's perspective rather than a practical perspective? The whole concept of legitimatizing an earlier move castling later in the line is resemblant of a joke problem. 

When I started in the logical retro field I believed the AP-type was a joke type. After about a year I discovered it was formalizable in the mathematical sense and now rate it as a fuzzy "gamble type". It's the logic-type of the moron who always gets things wrong and the type of the genius who recognizes hidden truth in a mass of confusing and contradictory data. It's the maverick logic.

Imagine a father of 2 brothers dies and leaves a castle to one of them. The other brother believes there is an overriding testament in a vault in the castle leaving it to him. Since he has no access to the castle he decides to break in and recover that will. If it doesn't confirm his expectations he goes to jail. However, when it does then he always was the castles legitimate owner and gets away with the break-in. Obviously, an idealized story but you get the idea! That's AP-logic.

How can White Castle while B1 is attacked by the Black Rook?

The king is not going through a check with him castling. It is therefore a legal move