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immpy
Joined: 06 May 2017
Posts: 574
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 Posted: Mon Oct 18, 2021 5:01 pm Post subject: VH 101821 |
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Hello all, enjoy the puzzle...
| Code: |
+-------+-------+-------+
| . . 4 | 3 7 9 | 8 . 6 |
| . . 9 | . 6 . | . . . |
| . 7 . | . 8 2 | 4 . . |
+-------+-------+-------+
| 4 . . | . . . | . . 5 |
| . . . | . . . | . 3 1 |
| 2 . . | . . . | . . 7 |
+-------+-------+-------+
| . 5 . | . 1 4 | 7 . . |
| . . 7 | . 5 . | . . . |
| . . 6 | 9 . 7 | 5 . 8 |
+-------+-------+-------+
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Play this puzzle online at the Daily Sudoku site
cheers...immp |
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Mogulmeister
Joined: 03 May 2007
Posts: 1151
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| Posted: Tue Oct 19, 2021 5:15 am Post subject: |
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One for everyone to try.
| Quote: | | After basics, an <123> XY wing in in blocks 8 and 9 will do it. |
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TomC
Joined: 30 Oct 2020
Posts: 359
Location: Wales
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| Posted: Tue Oct 19, 2021 7:00 am Post subject: |
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| Code: |
+--------------+----------------+-------------+
| 15 2 4 | 3 7 9 | 8 15 6 |
| 1358 138 9 | 4 6 15 | 13 7 2 |
| 6 7 13 | 15 8 2 | 4 159 39 |
+--------------+----------------+-------------+
| 4 1369 13 | 7 239 136 | 269 8 5 |
| 7 69 58 | 2568 4 568 | 269 3 1 |
| 2 1369 58 | 1568 39 13568 | 69 4 7 |
+--------------+----------------+-------------+
| 389 5 2 | 68 1 4 | 7 69 39 |
| 1389 138 7 | 268 5 368 | 13 1269 4 |
| 13 4 6 | 9 23 7 | 5 12 8 |
+--------------+----------------+-------------+
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Play this puzzle online at the Daily Sudoku site
There is an X-wing on 1's in rows 1 and 9 which doesn't quite work, but which led me to:
If r1c1=1, r3c3=3, r2c7=3, r8c7=1 gives no 1's in box 7 .... so r1c1 is 5 |
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Clement
Joined: 24 Apr 2006
Posts: 1113
Location: Dar es Salaam Tanzania
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| Posted: Tue Oct 19, 2021 7:06 am Post subject: VH 101821 |
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| Code: |
+--------------------+----------------------+------------------+
| 15 2 4 | 3 7 9 | 8 15 6 |
| 1358 138 9 | 4 6 a15 |a13 7 2 |
| 6 7 b13 |b15 8 2 | 4 159 b9-3|
+--------------------+----------------------+------------------+
| 4 1369 13 | 7 239 136 | 269 8 5 |
| 7 69 58 | 2568 4 568 | 269 3 1 |
| 2 1369 58 | 1568 39 13568 | 69 4 7 |
+--------------------+----------------------+------------------+
| 389 5 2 | 68 1 4 | 7 69 c39 |
| 1389 1389 7 | 268 5 368 | 1-3 1269 4 |
| 13 4 6 | 9 23 7 | 5 12 8 |
+--------------------+----------------------+------------------+
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Also a chain
(3=5)r2c76 - (5=9)r3r3c439 - (9=3)r7c9 => - 3r8c7,r3c9; stte |
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Mogulmeister
Joined: 03 May 2007
Posts: 1151
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| Posted: Tue Oct 19, 2021 9:32 am Post subject: |
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Building on Clement's nice chain we can strip back to the fact that a <13> remote pair in r3c3 and r2c7 are linked by the naked pair <15> in r3c4 and r2c6.
One of those <13> pairs will always be 3 so r2c12 and r3c9 <>3. (ed - Isn't this the good old M wing or W wing ? I forget which!) |
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Mogulmeister
Joined: 03 May 2007
Posts: 1151
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| Posted: Tue Oct 19, 2021 10:56 am Post subject: |
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Using Tom’s approach, we can also look at the <13> in r2c7.
If it is (not 3) = 1 then the 3’s in row 2 all belong in block 1 and r3c3 <> 3 but at the same time the link through the <15> pair in block 2 insist r3c3 is not 1 and must be 3. Following these there is nothing left in r3c3. Contradiction means that
R2c7 must be 3. |
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TomC
Joined: 30 Oct 2020
Posts: 359
Location: Wales
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| Posted: Wed Oct 20, 2021 6:54 am Post subject: |
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| Or another W wing <15> in r2c6 and r1c8 gives -1 r2c7 |
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