#693, April 11 - April 17, 2026:
The Weekly 'Unsolvable' Sudoku Puzzle
by Andrew Stuart
|
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).
|
Changes March 2026
Due to the introduction of
Forcing Nets many Weekly Unsolvable puzzles can now
be solved. I have flagged all the Sudoku ones which are solvable. I am struggling to make any new ones so we'll
have to see if the Weekly can continue. The point of the Weekly was to provoke discussion and new ideas, so
that is progress. But my solution is unlikely to be optimal so alternatives are welcome.
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.
Share and Enjoy
Supporter Members have access to all these puzzles going back to number 1.
Discussion...
Post an idea here...
... by: Yves
Aujourd’hui
Écrire un message à Copilot
Vous avez dit
Peux tu résoudre les sudokus ?
Copilote a dit
Oui, je peux résoudre des sudokus 🙂
Si tu veux, envoie‑moi une grille et je la résous étape par étape ou juste avec la solution finale, comme tu préfères.
Le plus simple est de :
Utiliser des zéros ou des points pour les cases vides
Une ligne par rangée, par exemple :
530070000
600195000
098000060
etc.
Tu veux qu’on en fasse un ensemble maintenant ?
Vous avez dit
9....2..5 .3.....7. ..1.6.8.. 7....5..2 ..6.1.9.. .4.2...8. ...8...9. ....4.3.. .....9..4
Copilote a dit
Je suis désolé, de ne pas pouvoir répondre aux demandes pour le moment. Veuillez réessayer dans quelques instants.
Écrire un message à Copilot
Afficher mes réflexions
Organiser mes pensées et créer un plan
Terminé
To give a Hand to Copilot for this #693 : G2=1 & B1= 4 Solve
1(6,1) And 4(1,0) notation [0->8 ; 0->8]
... by: XXX
dumping the literal sudoku into copilot gives a correct solution.
I did not expect LLMs to be able to solve sudokus.
but it was correct...
any way to make it LLM unsolvable/proof?
... by: Serban
# 693 H9=8 Basics 24
1. B5=H2=5 solve
2. C4=F6=3 solve
3. F7=H4=7 solve
4. H2=5 & J2=8 solve
... by: Frans Goosens
#693
With trial and error
Combination A2=678 and G9=167
************************************************************
A2=6 G9=1 No solution, Fixed
Combination 2-digits cells
A7=1 Wrong, Undo calculation
A7=4 Wrong, Undo calculation
All reset to initial position
************************************************************
A2=6 G9=6 Wrong, Undo calculation
All reset to initial position
************************************************************
A2=6 G9=7 ( A7=4 ) Solved,
Total solving time is : 91 sec.
Number of logical steps is : 12078
