Sudokuwiki.org's Weekly 'Unsolvable' Sudoku #645

  In this post I'll be tackling the weekly "Unsolvable" puzzle from SudokuWiki. This week's puzzle was provided by Andrew Stuart. 

Puzzle string: .1.....6.8..1....4..7.389..2....56......1......34....7..938.7..7....4..6.5.....9. - Sudoku.Coach

SE: 8.9

You read that right, today's puzzle is not even 9 SE! This is the first puzzle I've tackled that was not by Richard Kröger so I suppose we owe him credit for the extreme difficulty thus far. This was an enjoyable solve - I'm glad to have a break from the DoF chains.

After basics:

Two-String Kite

Finned X-Wing

Finned Swordfish

(7)r5c2 = r4c2 - (7=9)r4c5 - r4c9 = (9)r5c9 => r5c2<>9

Kraken X-Wing: (8)r19\c79 = (8-4)r9c3 = r45c3 - (4=789)r4c245 - r4c9 = (9)r5c9 => r45c9<>8

The 9c9 strong link is just a transport off the AIC that eliminates 8r4c9, to get a cheeky free elimination.

AHS-AIC: (38)(r1c9 = r1c17) - (3)r9c1 = (3-8)r9c9 = (8)r1c9 => r1c9<>25

ALS-AIC: (4=52)r7c89 - (2=83)r19c9 - r4c9 = (3)r4c8 => r4c8<>4

ALS-AIC: (1)r4c3 = r6c1 - r7c1 = (1-2)r7c6 = r9c456 - (2=83)r19c9 - r4c9 = (3)r4c8 => r4c8<>1

(4)r5c7 = r9c7 - r9c3 = (4-1)r4c3 = (1-5)r6c1 = (5)r6c78 => r5c7<>5

AHS-AIC: (14)(r9c3 = r48c3) - r7c1 = (1-6)r7c6 = (6)r7c12 => r9c3<>6

ER

(4)r9c3 = (4-1)r4c3 = r6c1 - r7c1 = (1-2)r7c6 = (2)r9c456 => r9c3<>2

(5)r7c9 = (5-4)r7c8 = r9c7 - r9c3 = (4-1)r4c3 = (1-9)r4c9 = (9)r5c9 => r5c9<>5

ALS-AIC: (9)r6c12 = r6c56 - (9=782)b5p124 - (2=9)r5c9 => r5c1<>9

Finned X-Wing

(3)r9c1 = (3-9)r1c1 = (9-7)r1c6 = (7-1)r9c6 = (1-6)r7c6 = (6)r7c12 => r9c1<>6

ALS-AIC: (4=561)r357c1 - r6c1 = (1-4)r4c3 = (4)r9c3 => r9c1<>4

AHS-AIC: (14)(r9c3 = r48c3) - (1)r8c78 = (1-4)r9c7 = (4)r9c3 => r9c3<>8

ALS-AIC: (5=382)b3p134 - (2=4)r5c7 - r5c8 = (4-5)r7c8 = (5)r7c9 => r3c9<>5

ALS-AIC: (5=68)r5c13 - (8=142)r489c3 - r12c3 = r3c2 - (2=15)r3c89 => r5c8<>5

Triple

Pair

X-Wing

(9=1)r6c1 - r4c3 = r4c9 - r3c9 = (1-5)r3c8 = (5-8)r6c8 = (8)r6c2 => r6c2<>9

STTE

Not much to say about this puzzle. Usually in these articles simple ALS-AIC would be left as small images with the Eureka underneath them... At first I was expecting the puzzle to get crazy difficult & for me to hit a wall like the others thus far, that's why I opened with the Kraken X-Wing, but that point never came. Even Sudoku.Coach's solver can solve it, albeit with Region/Cell Forcing Nets. At least it was fun!

See you next week when SudokuWiki retaliates with an 11.3 because I said the puzzle was too easy.