The New Sudoku Players' Forum

[m_b_metcalf]

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 . 1 2 . . . 3 . .
 . . 3 . . . 2 . .
 . . 4 . . . 5 . .
 . . 6 . . . 7 . .
 . . 5 3 7 8 4 . .
 . . 8 . . . 9 . .
 . . 9 . . . 6 . .
 . . 1 . . . 8 . .
 . . 7 . . . 1 4 .   moderate

 . 1 2 . . . 3 . .
 . . 3 . . . 4 . .
 . . 5 . . . 6 . .
 . . 1 . . . 2 . .
 . . 6 3 2 7 5 . .
 . . 8 . . . 9 . .
 . . 9 . . . 1 . .
 . . 7 . . . 8 . .
 . . 4 . . . 7 5 .   very hard

[Hajime]

The moderate one, after basics, needs 2 skyscrapers
Skyscraper (6)r1c6=r1c9-r6c4=r6c5 => (-6)r2c5
Skyscraper (5)r1c1=r2c1-r2c5=r4c5 => (-5)r4c4 (-5)r6c6
stte

The very hard one needed 2 backdoors one same cell:
(-5)r1c9 and (-8)r1c9 resulting in r1c9=7
and after basics: a bunch of X-chains of length 4 in cells (5 Turbot fishes) and one XY-chain (bivalue) of length 4.

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[13,8] 2-String-Kite,SkyScraper,TurbotCrane  |
2-String Kite (1)r6c5=r6c4-r9c1=r8c1 => (-1)r8c5
[14,8] 2-String-Kite,SkyScraper,TurbotCrane  |
Turbot Crane (3)r4c2=r8c2-r8c8=r9c9 => (-3)r4c9
[15,8] 2-String-Kite,SkyScraper,TurbotCrane  |
Turbot Crane (4)r1c1=r8c8-r8c5=r1c5 => (-4)r1c4 (-4)r1c6
[16,8] 2-String-Kite,SkyScraper,TurbotCrane  |
Turbot Crane (4)r8c5=r1c5-r1c1=r8c8 => (-4)r8c4 (-4)r8c6 (-4)r8c9
[17,8] 2-String-Kite,SkyScraper,TurbotCrane  |
2-String Kite (9)r4c5=r4c4-r9c9=r8c9 => (-9)r8c5
[18,8] XY-chain (bivalue) [cells<=10]  |
XY-chain [4]  (4)(4=8)r4c6-(8=9)r4c4-(9=3)r9c9-(3=4)r6c9 => (-4)r4c8 (-4)r4c9 (-4)r6c4
btte


[Leren]

Almost identical. With the extra hint r1c9 = 7 I saw one of Hahime's Turbot's as an X Wing on 4 => - 4 r1c46, r8c469 and used a slightly different XY chain of length 4. Other than that, the same.

Nice to see another participant in these threads.

Leren

[Hajime]

Nice to see another participant in these threads.

Just back from 4 weeks holiday without laptop