by Mohammed Hajooze
(Aleppo Syria)

  • First I use Orange to mark the start of color mapping, in this example the candidate is (1).
  • Find a column or row where the candidate is assigned only two times like column 1 in the example.
  • Hence R9C1 is true (1) then all cells in blue are false and all cells in green are true.

Now if R5C1 is true (1) then we can exclude the candidate (1) in all blue cells that shall be false again, in this example that would be the cells (R5C5, R6C5 and R5C9) and if any green cell shall be true again we can assign this candidate to this cell safely.