#643, April 26 - May 2, 2025:
The Weekly 'Unsolvable' Sudoku Puzzle
by Richard Kröger, guest compiler
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WARNING: This is the Weekly 'Unsolvable' Sudoku, rated above 'Extreme'.
This is currently unsolvable by my solver, except perhaps with trial and error strategies.
Using the solver will not help you. (much).
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Archive
Each week a new 'unsolvable' will be published and the previous will be accessible here from this archive section.
If you like very tough puzzles, these are for you.
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Discussion...
Post an idea here...
... by: Serban
# 643 Basics to 21
1. Number 1 n=3 e=6 N=24 Nc=21 Ns= => D9=1 basics to 42
1a. XY-Wing-349 [E47,D8] => D46 <>9 => E4=9 OR D6=8 basics to 66
1b. W-wing 58 [G3,B5] => B3 <>5 => G3=5 solve
2. C(3,4,9) D9(1,2,5,7,8,9) N=9 Nc=18 Ns=7 => C2=4 & D9=1 solve
... by: Dieter
#643 - basics: %
populated cells: 21 = 26%
strategy: try to get hidden pairs or triplets. No solver used.
combinations of A4 = (3,6,7,9) and A9 = (2,6,7,9)
5 matrices left after basic checks.
start with A4/A9 =(7/6), 58% populated: solves with A5=5
... by: Serban
# 643 Basics to 21
1. Row B n=3 e=6 Nc=24 Ns=18 => B3=9 & B5=8 solve
2. Box 4 ABC456 n=2 e=7 Nc=38 Ns=13 => A6=9 & B5=8 solve
