This post concludes the review of PencilPress’ 500+ Sudoku Extreme Puzzles, and adds another puzzle to the review update of Tom Sheldon’s Master Class Sudoku. T
The final score was PencilPress Extreme 0, Sysudoku Bypass 10. If “Extreme” means requiring very advanced techniques to solve, then the PencilPress book is extremely mislabeled. However, the cover and introduction do not display the overblown claims that “extreme” collections generally carry. Once accepted as a collection of basic level puzzles requiring the best of the Sysudoku Bypass repertoire, this collection is worth your time. It does require concentrated, if routine, effort, and offers no excuse for guessing, or trials of any kind.
Bottom right, page 81 follows the other 9 review puzzles in bypass defeat, but has a basic challenge for you. Here is the bypass trace:
As you’re reading the trace, here is your grid as you finish your trace back on the first leg, and encounter NE8 as a cause. Where does it go and why? First, look at the other 8 placements, and answer those questions. Then, if you did not spot NE8 this week, consider why not? It certainly isn’t “extreme”, is it? Also, note the fill of the South box.
Or if you’re among those who have the computer generate your candidates, and consider Sysudoku Basic a waste of time, you could save a lot of it by skipping Sudoku altogether.
The Master Class 110 bypass begins with a run of 1 placements, then a c2 4-fill NW3. This brings NE3 and another 4-fill on r3, N9.
After this short, but remarkable bypass, a 2-wing arrives at the Close, where marking of lines on the unfinished rows or columns is completed.
This time the Close is on columns. The fill lists signal a tough line marking.
With all candidates in place, an easily spotted, potentially lucrative unique rectangle appears in the West. It’s a type 4 UR, by the UR chart (Tools page). One 3-slink partner must be true, so neither of the ceiling 2-candidates can be, unless you’re willing to believe that Tom Sheldon published an obvious multiple solution puzzle.
With all candidates in place, an easily spotted, potentially lucrative unique rectangle appears in the West. It’s a type 4 UR, by the Tools chart. One 3-slink partner must be true, so neither of the ceiling 2-candidates can be, unless you’re willing to believe that Tom Sheldon published an obvious multiple solution puzzle.
The collapse of Master Class 110 is immediate.
Next, we finish the review update with Master Class 120.
It might be a good time to look at an early Sysudoku assessment of the instruction in Tom Sheldon’s Sudoku Master Class. Tom would likely place UR types 3 and 4, described above, deep in his logical Twilight Zone.