Mirrored from **Sudopedia**, the Free Sudoku Reference Guide

# Naked Subset

A **Naked Subset** is formed by **N** cells in a house with candidates for exactly **N** digits.

**N** is the size of the subset, which must lie between 2 and the number of unsolved cells in the house minus 2. Since every Naked Subset is complemented by a Hidden Subset, the smallest of both sets will be no larger than 4 in a standard sized Sudoku.

An alternative name for Naked Subset is **Number Chain**, but this term is not used very often.

## Names for Different Sizes

- Naked Pair
- Size 2

- Naked Triple
- Size 3

- Naked Quad
- Size 4

## Recognition

To recognize a **Naked Subset**, you probably need pencilmarks, unless you have a very good memory. A naked pair is easy to locate because you only need to spot two cells with candidates for the same two digits. A naked triple is more difficult to recognize, because not all three cells need to contain candidates for all three digits. Subsequently, a naked quad is even more difficult to spot.

When all cells are located in an intersection, spotting the subset is much easier. Because there are only 3 cells in an intersection, it is not possible to find Naked Quads in an intersection. The subset can cause eliminations in both intersecting houses. A size 2 is called a Locked Pair and size 3 is a Locked Triple.

## See Also

This page was last modified 12:13, 13 June 2007.