     Sudoku Solution Path   Copyright © Kevin Stone R8C5 can only be <9> R3C5 is the only square in row 3 that can be <2> R2C5 is the only square in column 5 that can be <4> Squares R1C1 and R1C9 in row 1 form a simple locked pair. These 2 squares both contain the 2 possibilities <47>. Since each of the squares must contain one of the possibilities, they can be eliminated from the other squares in the row.    R1C4 - removing <7> from <789> leaving <89>    R1C6 - removing <7> from <789> leaving <89> Squares R1C4 and R1C6 in block 2 form a simple locked pair. These 2 squares both contain the 2 possibilities <89>. Since each of the squares must contain one of the possibilities, they can be eliminated from the other squares in the block.    R3C4 - removing <9> from <379> leaving <37>    R3C6 - removing <9> from <379> leaving <37> Squares R3C4 and R3C6 in row 3 form a simple locked pair. These 2 squares both contain the 2 possibilities <37>. Since each of the squares must contain one of the possibilities, they can be eliminated from the other squares in the row.    R3C2 - removing <7> from <17> leaving <1>    R3C7 - removing <7> from <4679> leaving <469>    R3C8 - removing <7> from <467> leaving <46> R8C2 can only be <5> R7C2 can only be <3> R7C5 can only be <8> R5C5 can only be <3> Intersection of row 8 with block 9. The value <7> only appears in one or more of squares R8C7, R8C8 and R8C9 of row 8. These squares are the ones that intersect with block 9. Thus, the other (non-intersecting) squares of block 9 cannot contain this value.    R7C7 - removing <7> from <4567> leaving <456>    R7C8 - removing <7> from <14567> leaving <1456> Intersection of column 1 with block 4. The value <6> only appears in one or more of squares R4C1, R5C1 and R6C1 of column 1. These squares are the ones that intersect with block 4. Thus, the other (non-intersecting) squares of block 4 cannot contain this value.    R4C3 - removing <6> from <3568> leaving <358>    R6C3 - removing <6> from <13568> leaving <1358> Squares R3C6<37>, R7C6<57> and R9C6<35> in column 6 form a comprehensive locked triplet. These 3 squares can only contain the 3 possibilities <357>. Since each of the squares must contain one of the possibilities, they can be eliminated from the other squares in the column.    R4C6 - removing <5> from <5689> leaving <689>    R6C6 - removing <5> from <568> leaving <68> Intersection of column 6 with block 8. The value <5> only appears in one or more of squares R7C6, R8C6 and R9C6 of column 6. These squares are the ones that intersect with block 8. Thus, the other (non-intersecting) squares of block 8 cannot contain this value.    R7C4 - removing <5> from <157> leaving <17>    R9C4 - removing <5> from <135> leaving <13> Squares R5C3 and R5C8 in row 5 and R8C3 and R8C8 in row 8 form a Simple X-Wing pattern on possibility <1>. All other instances of this possibility in columns 3 and 8 can be removed.    R6C3 - removing <1> from <1358> leaving <358>    R7C3 - removing <1> from <146> leaving <46>    R7C8 - removing <1> from <1456> leaving <456> R7C4 is the only square in row 7 that can be <1> R9C4 can only be <3> R9C6 can only be <5> R3C4 can only be <7> R7C6 can only be <7> R3C6 can only be <3> Intersection of column 9 with block 6. The value <5> only appears in one or more of squares R4C9, R5C9 and R6C9 of column 9. These squares are the ones that intersect with block 6. Thus, the other (non-intersecting) squares of block 6 cannot contain this value.    R4C7 - removing <5> from <3578> leaving <378>    R5C7 - removing <5> from <578> leaving <78>    R5C8 - removing <5> from <157> leaving <17>    R6C7 - removing <5> from <3458> leaving <348> R5C3 is the only square in row 5 that can be <5> R5C8 is the only square in row 5 that can be <1> R6C1 is the only square in row 6 that can be <1> R9C1 can only be <4> R9C9 can only be <1> R1C1 can only be <7> R7C3 can only be <6> R1C9 can only be <4> R4C1 can only be <6> R2C2 can only be <8> R6C9 can only be <5> R3C8 can only be <6> R2C3 can only be <9> R5C2 can only be <7> R3C3 can only be <4> R3C7 can only be <9> R8C8 can only be <7> R5C7 can only be <8> R6C4 can only be <8> R4C9 can only be <7> R8C3 can only be <1> R8C7 can only be <6> R2C8 can only be <5> R2C7 can only be <7> R7C8 can only be <4> R4C7 can only be <3> R6C3 can only be <3> R6C6 can only be <6> R1C4 can only be <9> R4C6 can only be <9> R7C7 can only be <5> R1C6 can only be <8> R4C4 can only be <5> R4C3 can only be <8> R6C7 can only be <4> [Puzzle Code = Sudoku-20190625-VeryHard-161945]    