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.
Systematic Sudoku 