Coloring Bails Out Basic on III-34

In this last post of Moito’s Sudoku Road to Mastery, Basic drives the 0.91 rated III-34  into a near BUG blind alley with a flurry of subsets and boxlines, then hands off to coloring for a quick score.

A tight bypass resolves one 3-fill and leaves one. Then box and line marking go routinely until I prefer two 7f: final rows over a gaggle of columns, and finish the rows on r6.

The grid at that point  has the first subset, a modest naked pair. The pair removes four 8’s, but one of those removals brings more than a clue.





What happens is that C4 removes 4’s to create naked quad in r4 and a naked pair in c3.







The quad generates two boxline slinks, but the naked pair starts a collapse, which . . .



. . . stalls one cell short of a BUG. But no problem. Coloring reveals in c8 that green is impossible.








Next post begins a review of A.D Ardson’s Sudoku Diabolical, with # 30, shown here. Let’s compare solutions.

About Sudent

I'm John Welch, a retired engineering professor, father of 3 wonderful daughters and granddad to 7 fabulous grandchildren. Sudoku analysis and illustration is a great hobby and a healthy mental challenge.
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