Empty Rectangle
Advanced Logic25 / 32A box folded onto one row and one column beats a strong link.
Inside a box, a digit's candidates sometimes all crowd onto a single row plus a single column — leaving an empty rectangle in the remaining four cells. The box will place its digit on one of those two lines.
Combine that with a strong link elsewhere: if one link end lines up with the box's row, the other end shoots down a cell on the box's column (or vice versa). One glance at the box, one strong link, one elimination.
See it in action
Step 1 of 4
The setup
Scan boxes where one digit's candidates form an L or cross shape on a row and column. Then look for a two-spot line of the same digit with one end on that row or column. Step through this real position to see it happen.
Practice
Find the Empty Rectangle pattern and remove the digit from the intersection cell it convicts.
Drill 1 of 29Tap a cell, then the candidate digit you want to remove.