     Sudoku Solution Path   Copyright © Kevin Stone R4C1 can only be <6> R5C8 can only be <6> R6C9 can only be <2> R5C7 can only be <1> R4C9 can only be <5> R5C2 is the only square in row 5 that can be <8> R6C6 is the only square in row 6 that can be <7> R8C8 is the only square in row 8 that can be <5> Squares R6C1<39>, R7C1<139> and R8C1<139> in column 1 form a comprehensive locked triplet. These 3 squares can only contain the 3 possibilities <139>. Since each of the squares must contain one of the possibilities, they can be eliminated from the other squares in the column.    R1C1 - removing <19> from <12589> leaving <258>    R2C1 - removing <19> from <1289> leaving <28>    R9C1 - removing <139> from <12379> leaving <27> R2C5 is the only square in row 2 that can be <1> R1C3 is the only square in row 1 that can be <1> R2C9 is the only square in row 2 that can be <3> R3C5 is the only square in column 5 that can be <2> Squares R1C4 and R1C6 in row 1 form a simple locked pair. These 2 squares both contain the 2 possibilities <34>. Since each of the squares must contain one of the possibilities, they can be eliminated from the other squares in the row.    R1C7 - removing <4> from <456> leaving <56>    R1C9 - removing <4> from <4689> leaving <689> Intersection of column 5 with block 8. The value <4> only appears in one or more of squares R7C5, R8C5 and R9C5 of column 5. These squares are the ones that intersect with block 8. Thus, the other (non-intersecting) squares of block 8 cannot contain this value.    R9C4 - removing <4> from <1349> leaving <139>    R9C6 - removing <4> from <134> leaving <13> Intersection of block 8 with row 9. The value <1> only appears in one or more of squares R9C4, R9C5 and R9C6 of block 8. These squares are the ones that intersect with row 9. Thus, the other (non-intersecting) squares of row 9 cannot contain this value.    R9C9 - removing <1> from <14689> leaving <4689> Intersection of block 1 with column 2. The value <9> only appears in one or more of squares R1C2, R2C2 and R3C2 of block 1. These squares are the ones that intersect with column 2. Thus, the other (non-intersecting) squares of column 2 cannot contain this value.    R8C2 - removing <9> from <49> leaving <4>    R9C2 - removing <9> from <2469> leaving <246> R7C5 is the only square in column 5 that can be <4> Squares R1C7<56>, R3C7<456> and R3C9<46> in block 3 form a comprehensive locked triplet. These 3 squares can only contain the 3 possibilities <456>. Since each of the squares must contain one of the possibilities, they can be eliminated from the other squares in the block.    R1C9 - removing <6> from <689> leaving <89> Squares R6C1 and R8C5 form a remote locked pair. <39> can be removed from any square that is common to their groups.    R8C1 - removing <39> from <139> leaving <1> R8C9 can only be <9> R8C5 can only be <3> R1C9 can only be <8> R9C8 can only be <8> R5C5 can only be <9> R9C6 can only be <1> R9C4 can only be <9> R4C6 can only be <4> R4C4 can only be <1> R1C6 can only be <3> R5C3 can only be <3> R6C4 can only be <3> R6C1 can only be <9> R1C4 can only be <4> R7C1 can only be <3> R7C7 can only be <6> R7C3 can only be <9> R7C9 can only be <1> R1C7 can only be <5> R9C9 can only be <4> R9C7 can only be <3> R3C9 can only be <6> R1C1 can only be <2> R3C7 can only be <4> R3C3 can only be <7> R1C8 can only be <9> R2C1 can only be <8> R9C1 can only be <7> R2C2 can only be <9> R1C2 can only be <6> R2C8 can only be <2> R3C1 can only be <5> R9C3 can only be <6> R9C2 can only be <2> [Puzzle Code = Sudoku-20190212-VeryHard-132659]    