Aligned Pair Exclusion

Aligned Pair Exclusion (APE) finds eliminations by examining pairs of cells that are aligned in a row, column, or box, along with the cells they both see.

Pattern Recognition

To find an APE:

1. Identify two cells aligned in a unit (row, column, or box)
2. Find cells that see both aligned cells
3. Check if any candidate combinations in the aligned cells would force contradictions

How It Works

If placing a particular candidate in a cell that sees both aligned cells would leave no valid combination for those aligned cells, that candidate can be eliminated.

Example

Documentation stub - examples coming soon.

Related Techniques

• Almost Locked Sets — Another technique using candidate relationships
• Sue-de-Coq — Complex intersection patterns