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.

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About Sudent

My real name is John Welch. I'm a happily married, retired professor (computer engineering), timeshare traveling, marathon running father of 3 wonderful daughters and granddad to 7 fabulous grandchildren. The blog is about Sudoku solving. It covers how to start, basic solving to find candidates efficiently, and advanced solving methods in an efficient order of battle. It is about human solving methods, not computer solving.
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