Aligned Pair Exclusion

The cells I8 and D9 can together accept various combinations of values. But some combinations of values can be excluded, because they would leave some cells with no potential values.

More precisely, the following combinations of values are not possible for the cells I8 and D9:
9 and 5 because the cell F8 must contain 5 or 9
9 and 7 because the cell I9 must contain 7 or 9
9 and 8 because the cell D8 must contain 8 or 9

Because the value 9 of the cell I8 occurs in none of the remaining combinations, it can safely be removed.