This technique is very similar to the XY-Wing technique. Find a cell with candidates XYZ that has two buddies, XZ and YZ. The candidate Z can be eliminated from the intersection of XYZ, XZ, and YZ.
Consider the sudoku below.
The cell r9c1 can take the role of XYZ
, where X = 2 , Y = 9, and Z = 4.
The cell r8c3 takes the role of XZ
the cell r3c1 takes the role of YZ
. No matter what the value of XYZ is, one of
the three cells
must contain the digit 4. So we can remove the candidate 4 from
the intersection of the three cells
Note: The intersection of three cells is defined as the cells that share a unit with all three cells.
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Last Updated: 2/20/2019 1:59:00 PM CST