Locked Pairs

Locked Pairs

A locked pair is a special type of naked pair that occurs when two cells are positioned at the intersection of two houses (such as a row and a box). This positioning allows for candidate eliminations in both intersecting houses.

In the example below, look at cells R6C4 and R6C5 which both contain only candidates '1' and '3'. These cells form a naked pair in row 6.

However, since they are also located in the same box (bottom-left box), they become a locked pair with enhanced elimination power.