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VH 101821

 
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immpy



Joined: 06 May 2017
Posts: 570

PostPosted: Mon Oct 18, 2021 5:01 pm    Post subject: VH 101821 Reply with quote

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 |
+-------+-------+-------+

Play this puzzle online at the Daily Sudoku site

cheers...immp
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Mogulmeister



Joined: 03 May 2007
Posts: 1151

PostPosted: Tue Oct 19, 2021 5:15 am    Post subject: Reply with quote

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: 349
Location: Wales

PostPosted: Tue Oct 19, 2021 7:00 am    Post subject: Reply with quote

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  |
+--------------+----------------+-------------+

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: 1110
Location: Dar es Salaam Tanzania

PostPosted: Tue Oct 19, 2021 7:06 am    Post subject: VH 101821 Reply with quote

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  |
+--------------------+----------------------+------------------+
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

PostPosted: Tue Oct 19, 2021 9:32 am    Post subject: Reply with quote

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

PostPosted: Tue Oct 19, 2021 10:56 am    Post subject: Reply with quote

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: 349
Location: Wales

PostPosted: Wed Oct 20, 2021 6:54 am    Post subject: Reply with quote

Or another W wing <15> in r2c6 and r1c8 gives -1 r2c7
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