Unique Rectangle Type 2
In this case, we have two pure bi-value cells and two three-value cells sharing the same extra candidate, 2. So we are looking at Unique Rectangle Type 2
- Take a look at this example. One of the three-value cells must contain 2. Otherwise, if none of these cells contain 2, we get a “deadly pattern,” because the puzzle would have more than one valid solution for this grid configuration. In that case, each of the highlighted cells could take the values 6 and 9 in two different ways.
- So we can safely eliminate 2 from any cell that can see both of these cells at the same time
