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ZeroAssoluto
Joined: 05 Feb 2017
Posts: 1020
Location: Rimini, Italy
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 Posted: Tue Dec 28, 2021 10:46 am Post subject: Dec 28 VH |
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Hi everyone,
| Code: |
+-----------+------------+--------+
| 7 3 49 | 49 8 6 | 5 1 2 |
| 6 5 8 | 1 3 2 | 7 4 9 |
| 2 49 1 | 7 59 459 | 3 8 6 |
+-----------+------------+--------+
| 59 7 2 | 8 4 59 | 1 6 3 |
| 3 49 459 | 59 6 1 | 2 7 8 |
| 8 1 6 | 3 2 7 | 4 9 5 |
+-----------+------------+--------+
| 45 2 57 | 6 1 8 | 9 3 47 |
| 1 6 79 | 459 59 3 | 8 2 47 |
| 49 8 3 | 2 7 49 | 6 5 1 |
+-----------+------------+--------+
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Play this puzzle online at the Daily Sudoku site
| Quote: | Remote Pair 4,9 r5c2,r3c2,r1c3,r1c4 and -9 in r5c4
or
W-Wing
4,9 in r1c4,r9c6 SL with number 9 in r38c5 and -4 in r3c6,r8c4
5,9 in r3c5,r5c4 SL with number 5 in r8c45 and -9 in r1c4
4,9 in r3c2,r9c6 SL with number 9 in r38c5 and -4 in r3c6
4,9 in r1c4,r5c2 SL with number 4 in r3c26 and -9 in r5c4
5,9 in r4c6,r8c5 SL with number 5 in r3c56 and -9 in r9c6 |
Ciao Gianni |
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TomC
Joined: 30 Oct 2020
Posts: 359
Location: Wales
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| Posted: Tue Dec 28, 2021 11:39 am Post subject: |
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Using standard moves
X wing on <9> r49 removes 9 from r3c6
then XY wing <459> removes 5 from r3c5 |
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TomC
Joined: 30 Oct 2020
Posts: 359
Location: Wales
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| Posted: Tue Dec 28, 2021 12:51 pm Post subject: |
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| Or you could say r9c6 <> 9 as then r3c6 = 4, r1c4 = 9 leads to no <9>'s in box 5 |
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Mogulmeister
Joined: 03 May 2007
Posts: 1151
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| Posted: Tue Dec 28, 2021 2:38 pm Post subject: |
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| TomC wrote: | Using standard moves
X wing on <9> r49 removes 9 from r3c6
then XY wing <459> removes 5 from r3c5 |
Your almost XY wing starts out life with the extra 9 in r3c6.
If that 9 were true then there would be no 9’s in row 4 so we can dispense with it and the xy wing is true. |
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TomC
Joined: 30 Oct 2020
Posts: 359
Location: Wales
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| Posted: Tue Dec 28, 2021 2:52 pm Post subject: |
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If r3c6 was 9 then there would be no 9's in row 4 and no 9's in row 9 as well
Is that different to an X wing? |
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Mogulmeister
Joined: 03 May 2007
Posts: 1151
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| Posted: Tue Dec 28, 2021 4:19 pm Post subject: |
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The result is the same as the x wing but the logic is different as is the start point for 9 at r3c6 and it forces a contradiction.
The x wing is not about contradictions and we don’t know which of the vertices are +9 or -9 just that one is true and the other is false which is enough to eliminate the 9 at r3c6.
One is contradictory the other is not. |
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