Chess Online

What method does a puzzle decoding person use to untangle the apparent chaos of the position?

First, consider what arrangement of squares describes the ones where the escaping King can move: f4 & f3 (Include the one he's on, since he's not in check: e4). These 3 squares, f4, f3 and e4, make a small triangle 📐 on the board. Now compare this 📐 triangle to the move ranges of Black pieces which can soon move to coincide with this 📐 triangle.

The b3 Bishop can move to d5, from there its range covers two of the 📐 triangle squares, e4 & f3. That leaves just one more square, f4. So, what Black piece can be moved so that its range covers f4 after one move? There are 3: e7N, f2B, g6P. The N is ruled out because the two squares he'd have to move to would be occupied by other Black pieces; d5 by **the piece that kicks out the King**, and the other square, g6, is all ready occupied by a Pawn.

How about the Bishop? From f2 this Bishop would move to g3, but in so doing, he would abandon his cover of e3, allowing the K to escape toward the first rank.

So, this leaves the Pawn @ g6. Presuming the K can be forced out of e4 & f3, he would flee to f4, but the g6P could advance (g5+) to check him there. This P would not be guarded so the K would take him (...K×g5, forced). At this point we can return to the start, and review all the moves, to see what can be done when the K captures @ g5.

And we can find out what's **the piece that kicks out the King!**

When 1. Bd5+, the BQ can capture it. If so, 1...Q×d5, 2. Q×d5+ (former). If not, 1...Kf4, and the d5B remains to shield e5 from BQ (latter).

First, the latter case: 1. Bd5+...Kf4 (NOT forced), 2. g5+...K×g5 (forced), 3. Q×e5# (shielded from WQ by d5B). **B**

Second, the former case: 1. Bd5+...Q×d5, 2. Q×d5+...Kf4 (forced), 3. g5+...K×g5 (forced), 4. Q×e5#. **Q**