A General Logic for Sudoku
Rank 1 Double Loops with Rank 0 Branches
Points. Triplets affect the rank along the entire region belonging to its minor branch.
Rank 1 Double
This rank 1 double loop is formed from a bifurcation at 5r7c6 and a linkset triplet at 1r5c8. The triplet lowers the rank along its minor branch to rank 0 eliminating candidate 8r7c5. All linksets that are rank 0 are highlighted in black. The rank 0 region ends at bifurcation 5r7c6 because it has two independent return paths to the triplet's 2 linksets.
Rank 1 Double Loop with Rank 0 Branch
The second example is also a rank 1 double loop with
a linkset triplet at 1r2c9. The triplet's minor branch travels through 4 sets and 4 linksets
(highlighted black) until it reaches 1r1c5. The triplet lowers the rank along
the entire path to rank 0. However, the (red) candidate in