Bean’s Extremely Hard I


A review of Rebecca Bean’s 600 Extremely Hard Sudoku Puzzles with Answers begins with the review table and two puzzles, 7-6 and 12-6.

The collection is mostly basic, with the half of them solved by the slink marking bypass.

Puzzle 6 is selected from each of the 12 sections. Two of 12 sections reach the advanced level, loaded with bv.

 

In 7-6, a productive bypass leaves a simple box marking, and …

 

 

 

In 7-6, a productive bypass leaves a simple box marking, and …

The (46) bv shout out, and one string of four define a remote pair(red). Then an XY wing(black) and a longer XY chain (green) start a steep collapse:

 

 

 

 

 

 

Or, without the long XY chain, coloring brings a wrap of green, and blue wins.

 

 

 

 

 

 

 

 

On the second puzzle, 12-6, no graphics but a trace with multiple instances of the 3-fill recently added to Sysudoku Basic. The wide, flat trace profile is a typical result.

Next week, the Bean Extremely Hard review closes with puzzles 9-6 left and 11-6 right, below. Try them out.

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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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