2024/03/06 DPA: "Removing The Defender, By Your Hand Or Mine"

White to move.

Black has dark square weaknesses and no dark-squared Bishop for defense.

White would like play Qf6 to threaten Qg7#.  Note that Black has no viable checks other than ... Rxc3 so White has time for a setup move if needed.

Unfortunately, from a puzzle documentation standpoint, I saw the solution before any other line:  1. Qf6 Nxf6  2. Rd8+ Ne8  3. Rxe8#.

White recognizes that if the Knight moves, the d file opens up and if it doesn't move, he has checkmate on g7.

Can Black do anything to defend against 1. Qf6:  1. ... Rxc3+  2. bxc3 and Black has no more checks.

What's wrong with 1. Rxd5 to be followed with 2. Qf6?  There must be something wrong since puzzles can only have one solution.

If 1. Rxd5, White threatens 2. Qf6, against which there is no defense, and 2. Rd8+.

Aah, but 1. Rxd5 allows time for 1. ... exd5  2. Qf6 Qe1+ and Black can draw by three-fold repetition.

The key was seeing that removing the defender with 1. Rxd5 was too slow and going straight for checkmate resulted in removing the defender anyway but instead of us capturing it, it moved to deal with the immediate checkmate threat.

,

Black does have the defense 1. ... Qe3+  2. Bxe3 Nxf6  3. exf6, where White is up a piece but the eval is heavily in favor of White [+5].

Some might mistakenly think this invalidates the puzzle; it does not.  Puzzles do not require optimal moves for the opponent, only the solver.  If you found 1. Qf6, with the threat of 2. Qg7# and 2. Rd8+, you understood what the puzzle creator intended.  if you also saw 1. ... Qe3+ [I did not], that should not have prevented you from playing 1. Qf6.

https://www.chess.com/blog/EnPassantFork/no-the-puzzle-is-not-wrong