Proven Sudoku
Techniques / Exotic and rank-zero
Multi-Sector Locked Sets
Also called MSLS, Multi Sector Locked Sets.
New to this shorthand? How to read a sudoku grid explains r4c7, houses, candidates and the rest.
What it means
Count several rows, columns and boxes at once. If the numbers they need fill every spot they have, nothing is left over. Then every spare number in those squares can go.
The exact rule, for stronger players
The rule, stated exactly: A rank-zero configuration spanning several houses in which the number of truths supplied by the base sets exactly matches the cover capacity, licensing elimination of every candidate in the covers outside the bases.
What it removes: Remove all cover candidates not in a base set.
Why it works: A direct application of rank-zero logic across a larger, mixed collection of sets than a fish uses.
Worked examples
None yet. This pattern does not turn up in our daily boards, so there is no real example to show. We would rather wait than draw a fake one.
Learn these first
- Rank TheoryA way to count a pattern.
Related exotic and rank-zero
- Pattern Overlay MethodEvery digit has to land in one of a fixed set of shapes across the grid.
- Senior ExocetA bigger version of the Exocet pattern, with more squares acting as the target.
- SK LoopA ring of almost complete sets passing through the corners of a band and a stack.
- Table-Driven MethodsWork out ahead of time what follows from each single guess, and store it in a table.
- Broken WingA ring of squares where one number would have nowhere to go if the ring were perfect.
How often does it come up?
Our rough estimate: rare, appearing mainly in deliberately hard puzzles. When present it often resolves a large part of the grid.