PencilPress 65 and Master Class 90

This post continues the review of PencilPress Extreme Sudoku and the update of the review of Master Class Sudoku by Tom Sheldon.

Each PencilPress bottom right seems to have its own little novelty.  Hopefully, you found the one coming up in ppbr 65 after NW1, SW2, NE3, and SW3. If you consider the new SW box fill, and its missing values 4,5 and 7, two of those values see r7c1, placing the third value you know where.

Just as in line 3-fills, placement of one of the missing values gives us at least a naked pair in the other two cells.

Line 3-fills keep the placements coming in the remaining bypass trace.









Moving on to Master Class 90, we get clear examples worthy of The Guide about marking a partially line marked grid.



The first occurs on the second marked line r1, where a bv 38 matches another in c1. No more candidates can be added to r1c1, but the same cannot be said of r4c1, despite the fact that both 3 and 8 in r4c1 are box slink partners.  It’s not a naked pair yet.



You may remain unconvinced until c1 is marked, and 7 invades r1c4 to create a naked triple for NW5.







Line marking continues to the collapse with another naked triple and a 3-wing.








Here’s the basic trace.




Next week, the PencilPress Extreme review continues with bottom right, page 73 below.

PencilPress 73 Basic makes some interesting stops, and Pencil Press Extreme review finally breaks into box marking!

The update of Tom Sheldon’s Master Class review continues with Master Class 100, which illustrates again the enlistment of X-wings into line marking. That can be found nowhere else, until other Sudoku writers acknowledge the human engineering benefits of line marking itself.



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.
This entry was posted in Basic Solving Procedures, Puzzle Reviews, Tom Sheldon and tagged , , , , , , . Bookmark the permalink.

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