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.
... by: Yves
The full bi-cells trivial solutions with A3=9 (Serban does for #9)
A3=9 And
[B1=6 Or B2=2 Or B5=9 OR B8=5 Or C1=5 Or C4=6 Or C7=9 Or D1=2 Or D4=9 Or D5=5 Or D8=3 Or E3=1 Or F2=9 Or F5=7 Or F7=5 Or F9=2 Or G2=1 Or G6=2 Or G8=9 or G9=7 Or J1=9 Or J6=7 Or J7=2]
... by: Norman Powell
AS's Solver:
1) Singles A5=8
2) Pointing Pairs 1 in Row B and Box 2, eliminate 1 from B1, B2, B3 & B9
3) X-Cycles: Eliminate 5B3
4) Forcing Networks: Eliminate 1A7
5) Pointing Pairs 1 in Row C Box 3, eliminate 1 from C1, C2 & C3
Forcing Networks Eliminate 6) 3A8, 7) 2D9, 8) 3J4, 9) 4E4, 10) 3H4
11) Pointing Pairs 3 in Column 5 and Box 8, eliminated 3 from D5
Forcing Networks Eliminate 12) 2A2
Run out of known strategies.
My Solver: Finds solution during 4th pass of Forcing Networks - Details:
Hidden Singles In Box 2 A5 = 8. [AS#1]
Confined to Box Value 1 is confined to Row 2 and Box 2. [AS#2]
Finned-Swordfish CFG3576with Fin C1 for Value 5: Eliminate 5 from Cell B3 from Fin Box
[AS#3, X-Cycles instead, I have Finned Sword Fish earlier since for me it is a faster search]
Alt. Inf. Chains Value 1 of Cell A7 has weak links to both ends of the chain - Eliminate [AS#4]
[I usually have AIC deactivated since FN finds the same eliminations faster, today it is activated]
Confined to Box Value 1 is confined to Row 1 and Box 1. [AS#5, complimentary pattern found, same eliminations]
Forcing Networks First Pass: Eliminate 2A2 [AS#12], 3B8, 2D9 [AS#7], 3J4 [AS#8]
Forcing Networks Second Pass: Eliminate 4E4 [AS#9], 6F7
Forcing Networks Third Pass: Eliminate 5B1,
5B8 must be ON, eliminate other possibilities in B8, i.e. 5B8
Eliminate 9B8, 5C7, 3D4, 6D4, 3D5 [AS#11, pointing pairs], 5D8, 3H4 [AS#10]
Solved Cell: B8=5
Hidden Singles In Column 4 E4=3
Grouped Alt. Inf. Chains Value 9 of Cell C1 has weak links to both ends of the chain
[I usually have GAIC deactivated since FN finds the same eliminations faster, today it is activated]
Forcing Networks finds solution while testing 9A3 for ON, [includes AS#6 as part of bulk eliminations]
... by: Serban
# 723 A5=8 Basics to 23
1. A3 = any[B5,C7,D4,F2,G8,J1]=9 solve
2. A3=9 & D5=5 solve
3. A3=9 & B3=4 solve
