An XYZ-Wing upgrades the Y-Wing. The pivot now holds three candidates XYZ, and the wings are still XZ and YZ.
Because the pivot may already hold Z, you have weaker information — so you eliminate Z only from cells that see all three pattern cells.
Before this: Learn Y-Wing first.
Why it works
The pivot must be X, Y, or Z.
• If it is X, the XZ wing becomes Z. • If it is Y, the YZ wing becomes Z. • If it is already Z, then Z is true on the pivot.
In every case, Z is true somewhere among pivot + wings. Cells that see all three pattern cells see a Z either way — they cannot be Z.
Contradiction: assume a victim is Z → wings and pivot collapse into impossibility. Unlike Y-Wing, this pattern does not span four boxes the same way.
How to spot it
More localized than Y-Wing — usually only three boxes in a line. Eliminate only cells that see the pivot and both wings.
Demonstration
Find a pivot with candidates XYZ and two wings XZ and YZ that see the pivot.
The green cells are an XYZ-Wing. The common digit is 6. Notice the pivot may hold 6 too.
Every possible value of the pivot forces 6 into the pattern somewhere — wing, wing, or pivot itself.
Eliminate 6 only from cells that see the pivot and both wings (red). Weaker info means a smaller sting zone.
Example 1
Find a three-candidate pivot with matching bi-value wings.
This XYZ-Wing is about 3.
Remove 3 from cells that see all three pattern cells (red). Every pivot case places that digit in the wing group.
Example 2
Find a three-candidate pivot with matching bi-value wings.
This XYZ-Wing is about 6.
Remove 6 from cells that see all three pattern cells (red). Every pivot case places that digit in the wing group.