Agreement
Extreme
Used by Smart Hint
Whichever of a cell's candidates turns out true, every surviving line of play forces the same digit onto some other cell — so commit it.
- Cells that establish the pattern
- Where the conclusion lands
How it works
- Three cells must make 17. The middle one hangs off a 17-in-two down run, so it's 8 or 9; the last off a 16-in-two run, so it's 7 or 9. The first is already down to {1, 2}.
- Suppose the first cell is 1. The other two need 16 between them, and the only pair their candidates allow is 9 then 7.
- Suppose instead it's 2. Now they need 15 — only 8 then 7 works.
- The two branches disagree about the middle cell, so neither of them alone proves anything there. But both put a 7 at the end.
- Whichever branch is true, that cell is a 7 — so commit it without ever finding out which.