Pseudo Cell

When there are multiple cells in a unit that have to contain just one of a group of candidates these multiple cells are considered a Pseudo Cell.

A Pseudo Cell can be considered like an ordinary cell when searching for a locked set, strong links or weak links.The blue cells in Figure 1 are an example of a Pseudo Cell containing candidates 2 and 9 in row 4.

The Unique Rectangle in this example, made up of the blue and green cells, mandates that not both the 5 and the 7 can be used in the blue cells in row four.

The two blue cells in row four will need to be filled with a 5 or a 7 and one other value. The other value will have to come from the candidates 2 and 9 which are the only other candidates in the blue cells.

This creates a pseudo cell in row 4 that contains the candidates 2 and 9.

In this example the pseudo cell (the two blue cells) has been used with the red cell to create a naked set.