A Retrograde Analysis Problem

Two friends started playing a game of chess.  Partway through, they got up to take a snack break.  When they came back, they found the board and pieces exactly the way they left them (in the position shown above), but they couldn't remember whose turn it was.  Can you figure out whose turn it was?

Ah yes, it has to be _ _ _ _ _’_ turn! I am not spoiling!

where is the queen

Captured

Good puzzle - thanks.

All about working out if you can prove that both sides must have made the same number of moves (White to move), one has made more moves than the other (Black to move) or, alternatively, whether you can’t determine this.

Only one capture (the white Queen was captured on d1 by a black knight) and no promotions.

White:
King - Must have made an odd number of moves
a-pawn - Must have made an odd number of moves (only 1!)
Kingside rook - Must have made an odd number of moves
Queenside rook - Must have made an odd number of moves
Knights - Must have together made an even number of moves: they have either both stayed on the same colour square (even moves for each) or both switched colour squares (odd moves for each)
Overall - Must have made an even number of moves

Black:
a-pawn - Must have made an odd number of moves (only 1!)
h-pawn - Must have made an odd number of moves (only 1!)
Kingside rook - Must have made an odd number of moves
Queenside rook - Must have made an even number of moves or no moves
Knights - Must have together made an odd number of moves: one has switched colour squares (odd moves) and one has stayed on the same colour square (even moves).
Overall - Must have made an even number of moves


White to move!

I think the more important question is where these two freak shows learned how to play chess cause they must have played the most sewagey like in the history of chess. Ew.

 

Most retrograde analysis positions are not examples of stellar chess, since they take really weird and specific moves to get to them. Often completely illogical e.p. captures, underpromotions, kings taking early walks, or bishops trapping themselves behind enemy lines.

Retrograde analysis is more of a logic brain teaser, which moves are "good" doesn't matter for it. Only which moves are legal. The point is not to figure out which side played better, but to see if you can discern specific moves that happened in the game before the given position; or to figure out which rook started on a and which one on h just from a glance.

Like I remember a position with two white light-squared bishops and you needed to figure out which one was the original and which one was an underpromotion, only to get to the conclusion that both of them were underpromoted pawns. It'd have to have been a damn weird game for white if it was actually played, obviously.

Very interesting

It must be white to move. I’m not entirely sure, but I believe it’s impossible for it to be black’s move because neither side can ever lose a tempo.

It is interesting that people criticize retrograde problems on the basis of "bad chess" but please notice that probably all "win" puzzles are the result of "bad chess". Chess is basically a draw so for any side to get into a lost position they must first play "bad chess". Which makes all puzzles where white or black wins "unreal".

Actually, chess puzzles of all kinds do not particularly care about the goals of players before the diagram - but they do care about achieving them after it assuming any goals are implied or formulated. In fact, trying to win is not a mandatory aspect of playing chess. You will find most moms are trying to lose against their 10 year olds and wine when they fail. It's all inside the rules.