Aligned Oct Exclusion

The cells G1, I1, I3, G4, G5, G6, G7 and G9 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 G1, I1, I3, G4, G5, G6, G7 and G9:
0, 0, 0, 0, 0, 0, 7 and 7 because the value can occur only once in the region
0, 0, 0, 0, 0, 7, 7 and 0 because the value can occur only once in the region
2, 1, 3, 4, 6, 8, 7 and 5 because the cell G2 must contain 4 or 7
2, 1, 3, 4, 9, 6, 7 and 5 because the cell G2 must contain 4 or 7
2, 1, 3, 4, 9, 6, 7 and 8 because the cell G2 must contain 4 or 7
2, 1, 3, 4, 9, 8, 7 and 5 because the cell G2 must contain 4 or 7
2, 1, 3, 9, 6, 8, 7 and 5 because the cell G3 must contain 1 or 2
2, 1, 4, 4, 6, 8, 7 and 5 because the cell G2 must contain 4 or 7
2, 1, 4, 4, 9, 6, 7 and 5 because the cell G2 must contain 4 or 7
2, 1, 4, 4, 9, 6, 7 and 8 because the cell G2 must contain 4 or 7
2, 1, 4, 4, 9, 8, 7 and 5 because the cell G2 must contain 4 or 7
2, 1, 4, 9, 6, 8, 7 and 5 because the cell G2 must contain 4 or 7
2, 3, 4, 4, 6, 8, 7 and 5 because the cell G2 must contain 4 or 7
2, 3, 4, 4, 9, 6, 7 and 5 because the cell G2 must contain 4 or 7
2, 3, 4, 4, 9, 6, 7 and 8 because the cell G2 must contain 4 or 7
2, 3, 4, 4, 9, 8, 7 and 5 because the cell G2 must contain 4 or 7
2, 3, 4, 9, 6, 8, 7 and 5 because the cell G2 must contain 4 or 7
2, 4, 3, 4, 6, 8, 7 and 5 because the cell G2 must contain 4 or 7
2, 4, 3, 4, 9, 6, 7 and 5 because the cell G2 must contain 4 or 7
2, 4, 3, 4, 9, 6, 7 and 8 because the cell G2 must contain 4 or 7
2, 4, 3, 4, 9, 8, 7 and 5 because the cell G2 must contain 4 or 7
2, 4, 3, 9, 6, 8, 7 and 5 because the cell G2 must contain 4 or 7
5, 1, 3, 4, 9, 6, 7 and 8 because the cell G2 must contain 4 or 7
5, 1, 4, 4, 9, 6, 7 and 8 because the cell G2 must contain 4 or 7
5, 3, 4, 4, 9, 6, 7 and 8 because the cell G2 must contain 4 or 7
5, 4, 3, 4, 9, 6, 7 and 8 because the cell G2 must contain 4 or 7

Because some potential values of G7 occur in none of the remaining combinations, they can safely be removed.