Unique Rectangle 4X/1L
Unique Rectangle 4X/1L: Because the puzzle has exactly one solution, any pattern that would give two can be ruled out.
How it works on this board
Following the strong-link and outside-subset constraint, assuming the target makes the pattern swappable
2
8
6
7
5
3
7
9
8
5
3
6
2
5
3
6
7
2
9
5
7
6
2
3
9
9
6
1
3
7
8
2
4
5
5
6
7
5
7
5
2
7
7
4
1
5
No marks yetPosition 0 / 2