Reviewing James Forest’s Classic Sudoku

This post presents a Sysudoku solution of the Classic 24, from James Forest’s Book 30. We’ll do every 24th Classic. The first suggests an easy basic and an interesting diversity of advanced methods.

The bypass fills the East boxes with 20 placements, including naked pairs and two immediately resolved 3-fills.

How many UR signposts are there among the naked pairs in this line marked grid?

Out of five naked pairs, three possible UR’s call for a closer look, for Type 2b.

The same bv are also covered in an unproductive scan for Sue de Coq.





The UR is there.

On the bv map, no ANL, but the single i471-wing defines a toxic set.  No victims, but we can  leave the toxic set markers on the grid copies, as we move on to the X-panels.





The 4-panel closes Classic 24 out with a finned swordfish. 4r6c1 is the fin, and the removal of 4r4c2 in the fin box brings in C4 and the collapse. It turns out that two of the toxic set members are true.






Next time, James Forest’s Classic 48 will carry us further along. Can you say just how far?

The Guide pages on the Unique Rectangle and AIC Building are updated.




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.
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