SIC 3x3{1}
Difficulty D · Section: Inward Chains
Explanation
Found by: 84436
The black box will contain 4-7 mines
On the image on the left, the black box contains 2-4 mines
4 Mines is the only valid option then.
We can now use a kind of “local minecount” to make eliminations
If any of the multicolored cells are mines, they will satisfy 2 colors, although each color will only have one mine, therefore the mulitcolored cells are safe.
Of course, you can also use contradiction by assuming one of the 7 safe cells are mines and seeing that they are invalid.
Additional images


