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Mogulmeister
Joined: 03 May 2007 Posts: 1151
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Posted: Wed Nov 10, 2021 7:48 am Post subject: NOV 10th VH |
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Code: |
+-------+-------+-------+
| . . 7 | 9 6 . | 4 5 . |
| . . . | . . . | 1 9 . |
| . 2 . | . . . | . . 6 |
+-------+-------+-------+
| 5 . . | . 3 1 | . . . |
| . . . | 6 . 7 | . . . |
| . . . | 2 5 . | . . 8 |
+-------+-------+-------+
| 3 . . | . . . | . 1 . |
| . 5 9 | . . . | . . . |
| . 6 4 | . 9 5 | 3 . . |
+-------+-------+-------+
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Mogulmeister
Joined: 03 May 2007 Posts: 1151
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Posted: Wed Nov 10, 2021 7:51 am Post subject: |
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478 XY wing. |
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TomC
Joined: 30 Oct 2020 Posts: 358 Location: Wales
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Posted: Wed Nov 10, 2021 9:17 am Post subject: |
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At this point in the puzzle the 478 XY wing reveals itself
Code: |
+-------------+--------------+-------------+
| 8 1 7 | 9 6 23 | 4 5 23 |
| 46 34 356 | 3578 278 238 | 1 9 23 |
| 9 2 35 | 35 1 4 | 78 78 6 |
+-------------+--------------+-------------+
| 5 478 268 | 48 3 1 | 267 2467 9 |
| 24 9 238 | 6 48 7 | 5 234 1 |
| 467 347 1 | 2 5 9 | 67 3467 8 |
+-------------+--------------+-------------+
| 3 78 28 | 47 247 6 | 9 1 5 |
| 127 5 9 | 1378 278 238 | 268 268 4 |
| 12 6 4 | 18 9 5 | 3 28 7 |
+-------------+--------------+-------------+
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Play this puzzle online at the Daily Sudoku site
But what struck me was that r7c5 <> 2 as then r5c5=4, r5c1=2 results in no 2's in box 7 |
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Mogulmeister
Joined: 03 May 2007 Posts: 1151
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Posted: Wed Nov 10, 2021 11:42 am Post subject: |
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Nice one. If you plug the 2 into r7c5 and follow that loop you also put a 2 in r7c3 giving two 2’s in row 7.
(2-47)r7c5=4r5c5-(4=2)r5c1-r89c1=2r7c3 contradiction |
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TomC
Joined: 30 Oct 2020 Posts: 358 Location: Wales
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Posted: Wed Nov 10, 2021 2:34 pm Post subject: |
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Another way to look at this contradiction is to travel in a different direction
If r7c5=2 then r89c1=2, r5c1=4, r5c5=8 and no place for a 4 in c5 |
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Mogulmeister
Joined: 03 May 2007 Posts: 1151
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Posted: Wed Nov 10, 2021 4:19 pm Post subject: |
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Wrong (right) in so many ways ! |
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