R/C-on-B Shadowing

R/C-on-B Shadowing (Row/Column-on-Block Shadowing)

External synonyms:  cross-hatching, slicing & dicing.
Related external ideas:  squeezing.

Here, we focus on one Block.

In the example shown below, there are lots of 8s already on the Grid. But the Block that's highlighted still needs an 8.

Any 8 in a Row passing through the Block will horizontally shadow three Cells of the Block, forbidding the placement of an 8 in the shadowed Cells.

And any 8 in a Column passing through the Block will vertically shadow three Cells of the Block, preventing the placement of an 8 in those Cells.

If the Shadowing Tactic leaves more than one empty Cell unshadowed, then the Tactic fails (for that digit in that Block).

Check every Block this way for the digits it still needs.

Many people work on the three Blocks in a (horizontal) Band, concentrating first on Row-Shadowing and then adding in Column-Shadowing. They do all three Bands this way.

And then they work on the three Blocks in a (vertical) Tower, concentrating first on Column-Shadowing and then adding in Row-Shadowing. And they do all three Towers this way.

But the placement of any digit in any Block eliminates one empty Cell in that Block, and it increases the overall number of Shadow-producing digits, so that this Tactic has to be carried out iteratively over the whole Grid until you don't see any more opportunities.

You will develop your own preferences for the order in which you proceed, but with practice you'll learn to do this very fast.