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.