     Sudoku Solution Path   Copyright © Kevin Stone R3C4 can only be <9> R4C3 can only be <7> R5C1 can only be <5> R5C4 can only be <4> R5C9 can only be <6> R6C3 can only be <2> R7C4 can only be <2> R7C6 can only be <8> R4C5 can only be <9> R4C7 can only be <3> R6C5 can only be <6> R5C5 can only be <7> R5C6 can only be <1> R6C7 can only be <9> R1C5 can only be <8> R7C1 can only be <9> R3C6 can only be <6> R9C5 can only be <5> R3C2 is the only square in row 3 that can be <7> R7C7 is the only square in row 7 that can be <7> R8C8 is the only square in row 8 that can be <2> R3C8 is the only square in column 8 that can be <3> Squares R3C3 and R3C7 in row 3 and R9C3 and R9C7 in row 9 form a Simple X-Wing pattern on possibility <4>. All other instances of this possibility in columns 3 and 7 can be removed.    R2C3 - removing <4> from <4568> leaving <568>    R2C7 - removing <4> from <4568> leaving <568>    R7C3 - removing <4> from <1456> leaving <156> Squares R2C3 and R2C7 in row 2 and R8C3 and R8C7 in row 8 form a Simple X-Wing pattern on possibility <8>. All other instances of this possibility in columns 3 and 7 can be removed.    R3C3 - removing <8> from <458> leaving <45>    R3C7 - removing <8> from <458> leaving <45>    R9C3 - removing <8> from <1348> leaving <134>    R9C7 - removing <8> from <148> leaving <14> Squares R3C3 and R3C7 in row 3 form a simple locked pair. These 2 squares both contain the 2 possibilities <45>. Since each of the squares must contain one of the possibilities, they can be eliminated from the other squares in the row.    R3C9 - removing <5> from <258> leaving <28> R7C9 is the only square in column 9 that can be <5> R7C3 is the only square in row 7 that can be <1> Squares R1C7 (XY), R9C7 (XZ) and R2C8 (YZ) form an XY-Wing pattern on <4>. All squares that are buddies of both the XZ and YZ squares cannot be <4>.    R7C8 - removing <4> from <46> leaving <6>    R3C7 - removing <4> from <45> leaving <5> R3C3 can only be <4> R7C2 can only be <4> R2C8 can only be <4> R8C7 can only be <8> R2C7 can only be <6> R9C9 can only be <1> R9C7 can only be <4> R1C9 can only be <2> R1C1 can only be <3> R3C9 can only be <8> R1C7 can only be <1> R2C2 can only be <5> R9C3 can only be <3> R3C1 can only be <2> R9C1 can only be <8> R1C3 can only be <6> R8C3 can only be <5> R2C3 can only be <8> R8C2 can only be <6> [Puzzle Code = Sudoku-20190620-SuperHard-273836]    