     Sudoku Solution Path   Copyright © Kevin Stone R5C1 can only be <3> R2C7 is the only square in row 2 that can be <8> R3C3 is the only square in row 3 that can be <2> R3C2 is the only square in row 3 that can be <1> R5C2 can only be <9> R5C8 can only be <7> R4C3 can only be <7> R5C6 can only be <5> R5C9 can only be <8> R6C3 can only be <1> R5C5 can only be <6> R5C4 can only be <1> R3C4 is the only square in row 3 that can be <6> R4C5 is the only square in row 4 that can be <2> R4C6 is the only square in row 4 that can be <4> R6C4 is the only square in row 6 that can be <8> R7C8 is the only square in row 7 that can be <2> R7C3 is the only square in row 7 that can be <8> R9C7 is the only square in row 9 that can be <1> R8C3 is the only square in column 3 that can be <9> R2C3 is the only square in column 3 that can be <6> Squares R4C7 and R6C7 in column 7 form a simple locked pair. These 2 squares both contain the 2 possibilities <39>. Since each of the squares must contain one of the possibilities, they can be eliminated from the other squares in the column.    R1C7 - removing <3> from <345> leaving <45>    R3C7 - removing <39> from <34579> leaving <457>    R7C7 - removing <3> from <3567> leaving <567>    R8C7 - removing <3> from <3567> leaving <567> Squares R7C4<39>, R7C6<379> and R7C9<37> in row 7 form a comprehensive locked triplet. These 3 squares can only contain the 3 possibilities <379>. Since each of the squares must contain one of the possibilities, they can be eliminated from the other squares in the row.    R7C2 - removing <3> from <346> leaving <46>    R7C7 - removing <7> from <567> leaving <56> Squares R1C3 and R1C5 in row 1 and R9C3 and R9C5 in row 9 form a Simple X-Wing pattern on possibility <3>. All other instances of this possibility in columns 3 and 5 can be removed.    R2C5 - removing <3> from <349> leaving <49>    R6C5 - removing <3> from <379> leaving <79>    R8C5 - removing <3> from <357> leaving <57> Squares R2C2 and R2C8 in row 2 and R8C2 and R8C8 in row 8 form a Simple X-Wing pattern on possibility <3>. All other instances of this possibility in columns 2 and 8 can be removed.    R3C8 - removing <3> from <359> leaving <59> Squares R8C8 (XY), R8C2 (XZ) and R7C7 (YZ) form an XY-Wing pattern on <6>. All squares that are buddies of both the XZ and YZ squares cannot be <6>.    R7C2 - removing <6> from <46> leaving <4>    R8C7 - removing <6> from <567> leaving <57> R7C1 can only be <5> R2C2 can only be <3> R2C8 can only be <9> R8C2 can only be <6> R1C3 can only be <5> R2C5 can only be <4> R3C8 can only be <5> R3C1 can only be <4> R8C8 can only be <3> R1C7 can only be <4> R7C7 can only be <6> R9C3 can only be <3> R7C9 can only be <7> R9C5 can only be <5> R8C5 can only be <7> R1C5 can only be <3> R3C7 can only be <7> R3C9 can only be <3> R8C7 can only be <5> R3C6 can only be <9> R6C5 can only be <9> R7C6 can only be <3> R6C7 can only be <3> R4C4 can only be <3> R6C6 can only be <7> R4C7 can only be <9> R7C4 can only be <9> [Puzzle Code = Sudoku-20191023-SuperHard-252730]    