IMPLIED CLEAR

Implied Clear

The hazard cell at C5-R4 requires a single mine which can only be placed at C4-R4 or C6-R5. At this point we don't know which one it will be, but in either case it will be adjacent to the hazard cell at C5-R5 and will completely satisfy its requirement. No further mines will be required, and this implies that the three highlighted cells must be cleared.