R2C4 can only be <1>

R7C4 can only be <5>

R6C4 can only be <4>

R8C4 can only be <7>

R5C5 can only be <1>

R6C5 can only be <6>

R4C5 can only be <3>

R4C6 can only be <5>

R1C7 is the only square in row 1 that can be <1>

R2C3 is the only square in row 2 that can be <3>

R3C1 is the only square in row 3 that can be <7>

R1C5 is the only square in row 1 that can be <7>

R3C9 is the only square in row 3 that can be <4>

R4C8 is the only square in row 4 that can be <6>

R4C2 is the only square in row 4 that can be <7>

R5C8 is the only square in row 5 that can be <7>

R8C7 is the only square in row 8 that can be <3>

R9C5 is the only square in row 9 that can be <4>

R9C9 is the only square in row 9 that can be <7>

R1C3 is the only square in column 3 that can be <6>

R2C6 is the only square in row 2 that can be <6>

Squares R8C5 and R8C6 in row 8 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 row.

R8C1 - removing <89> from <1589> leaving <15>

R8C2 - removing <89> from <5689> leaving <56>

R8C8 - removing <89> from <12589> leaving <125>

Squares R1C1 and R1C2 in block 1 form a simple locked pair. These 2 squares both contain the 2 possibilities <59>. Since each of the squares must contain one of the possibilities, they can be eliminated from the other squares in the block.

R2C1 - removing <59> from <4589> leaving <48>

R2C2 - removing <59> from <24589> leaving <248>

R3C3 - removing <9> from <289> leaving <28>

Intersection of row 4 with block 4. The value <1> only appears in one or more of squares R4C1, R4C2 and R4C3 of row 4. These squares are the ones that intersect with block 4. Thus, the other (non-intersecting) squares of block 4 cannot contain this value.

R6C3 - removing <1> from <12589> leaving <2589>

R4C3 is the only square in column 3 that can be <1>

R4C1 can only be <4>

R4C7 can only be <2>

R2C1 can only be <8>

R2C5 can only be <9>

R3C3 can only be <2>

R8C5 can only be <8>

R3C6 can only be <8>

R3C8 can only be <9>

R2C2 can only be <4>

R8C6 can only be <9>

R5C7 is the only square in row 5 that can be <4>

R6C2 is the only square in row 6 that can be <2>

R6C3 is the only square in row 6 that can be <9>

R9C7 is the only square in row 9 that can be <9>

R7C7 can only be <8>

R6C7 can only be <5>

R9C8 can only be <5>

R9C3 can only be <8>

R2C8 can only be <2>

R2C9 can only be <5>

R8C8 can only be <1>

R6C9 can only be <1>

R6C8 can only be <8>

R7C9 can only be <6>

R7C2 can only be <9>

R8C9 can only be <2>

R8C1 can only be <5>

R5C3 can only be <5>

R5C2 can only be <8>

R7C1 can only be <1>

R1C2 can only be <5>

R8C2 can only be <6>

R1C1 can only be <9>