Locked Candidates
A solving technique that uses the intersections between lines and boxes.
Aliases include: Intersection Removal, Line-Box Interaction. The terms Pointing and Claiming / Box-Line Reduction are often used to distinguish the 2 types.
This is a basic solving technique. When all candidates for a digit in a house are located inside the intersection with another house, we can eliminate the remaining candidates from the second house outside the intersection.
Type 1 (Pointing)
All the candidates for digit X in a box are confined to a single line (row or column). The surplus candidates are eliminated from the part of the line that does not intersect with this box.
Legend:X : cell which may contain a candidate for digit X
- : cell which does not contain a candidate for digit X
* : cell from which we may eliminate the candidates for digit X
Depending on the number of available candidates in the intersection, this technique is also known as a Pointing Pair or Pointing Triple.
Type 2 (Claiming or Box-Line Reduction)
All the candidates for digit X in a line are confined to a single box. The surplus candidates are eliminated from the part of the box that does not intersect with this line.
Example
Sudoku Games
- Sudoku 9981
- Samurai Sudoku
- Sudoku2PDF Pro
- Sudoku2PDF
- Printable samurai sudoku
- Word Sudoku to Learn French (German , Spanish)
Sudoku strategies
- Coloring
- Singles
- Fish
- Chains and Loops
- Intersections
- Subsets
- Wings
- Single Digit Patterns
- Uniqueness
- Almost Locked Sets
