#639, March 29 - April 4, 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
# 639 Basics to 21
1. X-chain x=2 => E7<>2 ; X-chain x=7 => [BE2,B4,E7]<>7 => basics to 21
2. Number 7 n=3 e=6 N=16 Nc=2 Ns=3 => any[A2,E1,B5,H4,E7,G8]=7 basics to 34
-- 2a. Column 1 n=4 e=5 Nc=5 Ns=1 => F1=8 solve
--2b . if J2=8 =>F1=8 solve
... by: Dieter
Better option: combinations of B4 / B6 = (2,5,6,7,9) / (5,6,7,9)
B4=5 & B6=7 solve.
... by: Dieter
#639 - basics: %
strategy: try to get hidden pairs or triplets. No solver used.
combinations of B6 / E6 = (5,6,7,9) / (1,5,6,9)
After basic checks > 3 matrices left: B6/E6 = (5/9) , (6/9) and (7/5)
start with B6/E6 = (6/9), 47% populated > failed with C1 = (3,6)
continue with B6/E6 = (7/5), 44% populated > solves with B5=2
