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Tuesday 24-Apr-2018

... by: Neil

My Ariadne's Thread solver finds 24 shortcuts (I didn't check for any more than that). b6=4 and a3=6 gives the solution.

Sunday 22-Apr-2018

... by: ghfick

Hi David,

U292 is minimal and has a rating of 11.1; 11.1; 9.9. It is not on champagne's 'potential hardest' list as of December 2017.

There is an MSLS c2468 r3679 Home : 1236 Away : 45789. This gives 19 exclusions [same as the MultiFish], then there are 4 more exclusions from a Hidden Triple, then one more exclusion from an AIC. Then Andrew's solver ROOKS [sounds like a chess move!]


Sunday 22-Apr-2018

... by: Paolo Calaresu

If R1C3=6=> It is formed the “Back-door “ R4C1=1
6R1C3+2R4C1=> contradiction (R5C6=Ř)
6R1C3+7R4C1=> contradiction (R3C6=Ř)
6R1C3+4R4C1+4R3C2=> contradiction (R9C2=Ř)
6R1C3+4R4C1+5R3C2=> contradiction (R1C5=Ř) =>R4C1=1 =>solution with basix strategies “backdoor”

To demonstrate the uniqueness of the solution:
Found Multi-Fish pattern with base set of 1,2,3 and 6
16 Truths = {1236R3, 1236R6, 1236R7, 1236R9}
16 Links = {6c2, 13c4, 23c6, 12c8, R3C1, R3C7, R6C3, R6C9, R7C1,R7C9, R9C3, R9C5, R9C7}
19 Eliminations: r3c1<>4, r3c1<>5, r3c7<>4, r6c3<>7, r7c1<>5, r9c3<>7, r9c3<>8, r9c5<>7, r9c7<>4, r9c7<>8, r1c4<>3, r2c6<>2, r4c4<>1, r4c4<>3, r4c8<>1, r4c8<>2, r5c4<>1, r5c6<>2, r8c6<>3

6R9C3=> contradiction=>-6R9C3
6R8C3+3R4C5=> contradiction
6R8C3+3R8C5=> contradiction
6R8C3+3R1C5=> contradiction=>-6R8C3
6R6C3+7R6C2=> contradiction
6R6C3+9R6C2+1R5C9=> contradiction
6R6C3+9R6C2+2R5C9=> contradiction
6R6C3+9R6C2+4R5C9+7R5C3=> contradiction
6R6C3+9R6C2+4R5C9+7R5C4=> contradiction
6R6C3+9R6C2+4R5C9+7R5C6=> contradiction
6R6C3+9R6C2+4R5C9+7R5C8=> contradiction=>-6R6C3=>R1C3=6=>solution.

Saturday 21-Apr-2018

... by: Frans Goosens

F3=1 No solution,
Assume F3=1 is right

Calculate 2 digits cells

A3=3 Wrong, Undo calculation
A3=6 Solved,

726 931 854
581 674 239
349 582 617

195 726 348
437 815 962
862 349 571

254 193 786
618 257 493
973 468 125

Saturday 21-Apr-2018

... by: David Filmer

Hi Gordon,

Thanks for your helpful comments on #291.

You said "Between 10.7 and 10.3 SE, to make the list, the first 2 numbers must be the same. i.e 10.3/10.3/10.1".

This week I post one rated at SE 11.00;11.00;9.70, which ROOKS immediately and would welcome your comments and analysis.

Best Regards,



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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