Queens: regions that share rows
If two regions fit inside the same two rows, those rows’ two queens are theirs. Cross out everything else in both rows.
How it works
Every region needs one queen, and every row holds exactly one. Count both sides and a group of regions can claim a group of rows.
Two regions that sit inside the same two rows need two queens there. Those two rows hold exactly two queens. So both of the rows’ queens belong to the two regions, and no other square in those rows can have one.
It is the same idea as a region in one row, scaled up. Hints call it “Two regions in two rows”.
Columns, and the reverse
Everything here works for columns. Two regions inside two columns own those columns’ queens.
It also works in reverse. If the open squares of two rows all lie inside two regions, those regions’ queens are in those rows, and the regions’ other squares are out.
Where to look
Look along the edges, where regions are often squeezed into a band of two or three rows. Count the regions that fit inside the band. If the count matches the number of rows, the band belongs to them.
Three regions in three rows is the same argument with three queens. The weekly puzzle often needs it.
Worth memorizing
k regions inside k rows own all k of those rows’ queens.
Cross out the rest of the rows.
Same for columns.
Reverse it: k rows inside k regions clear the rest of those regions.
Practice
0 of 2 rightWhich two regions fit together inside rows 1 and 2?
E and F fit inside rows 1 and 2. How many other squares of those rows can you cross out?