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Evil 20220225

 
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Clement



Joined: 24 Apr 2006
Posts: 1110
Location: Dar es Salaam Tanzania

PostPosted: Fri Feb 25, 2022 8:12 pm    Post subject: Evil 20220225 Reply with quote

Code:

+-------+-------+-------+
| 4 . . | . . 7 | . . . |
| . . 3 | 1 . . | . . 4 |
| . . . | . 5 . | 1 7 . |
+-------+-------+-------+
| . 4 . | 5 . . | 9 . . |
| . . 5 | . 2 . | . 6 . |
| 6 . . | . . 9 | . . 8 |
+-------+-------+-------+
| . . 2 | 7 . . | . . 6 |
| . . . | . 3 5 | . 2 . |
| . 8 . | . . . | 3 . . |
+-------+-------+-------+

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TomC



Joined: 30 Oct 2020
Posts: 349
Location: Wales

PostPosted: Sat Feb 26, 2022 10:01 am    Post subject: Reply with quote

Thanks Clement, I took a very long time to get anywhere with this, but got there in the end!

Code:

+-------------------+-------------------+-----------------+
| 4     12569 1689  | 23689  689  7     | 2568 3589  2359 |
| 25789 25679 3     | 1      689  268   | 2568 589   4    |
| 289   269   689   | 234689 5    23468 | 1    7     239  |
+-------------------+-------------------+-----------------+
| 12378 4     178   | 5      1678 1368  | 9    13    1237 |
| 13789 1379  5     | 348    2    1348  | 47   6     137  |
| 6     1237  17    | 34     147  9     | 2457 1345  8    |
+-------------------+-------------------+-----------------+
| 1359  1359  2     | 7      1489 148   | 458  14589 6    |
| 179   1679  14679 | 4689   3    5     | 478  2     179  |
| 1579  8     14679 | 2469   1469 1246  | 3    1459  1579 |
+-------------------+-------------------+-----------------+

Play this puzzle at the Daily Sudoku site

Quote:
You can remove the <8>'s in r138c4 ( and r4c56, r5c6 ) as this would give a <34> pair in box 5 which means that r3c6 would be <3> and <4> at the same time

So r5c4=8 and then fairly straitforward to finish
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Mogulmeister



Joined: 03 May 2007
Posts: 1151

PostPosted: Sun Feb 27, 2022 11:52 am    Post subject: Reply with quote

Nice observation to a very intriguing puzzle, Tom. Thanks Clement.

Your <34> pair Tom, that is created by r5c4 < > 8, also creates a quad in box 2 <2689> which would leave r2c6 empty.

The ANP <348> is stark.

r56c4(8=34) is impossible so r56c4(34=8 ) is the solution.


Last edited by Mogulmeister on Mon Feb 28, 2022 8:54 am; edited 4 times in total
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Mogulmeister



Joined: 03 May 2007
Posts: 1151

PostPosted: Sun Feb 27, 2022 12:19 pm    Post subject: Reply with quote

Which made me look at ALS possibilities:




Set A (Yellow) is {2,3,4,6,8,9}
Set B (Green) is {3,4)

Target cell (red) is r5c4

This is one of those very rare events (I have only seen it a handful of times) where there is more than one restricted common. We can make eliminations here using both 3 and 4 as the restricted common. So:

Restricted common 3 means we can eliminate 4 from r5c4 because it is seen by both 4's in Set A and Set B ie r3c4 and r6c4

Restricted common 4 means we can eliminate 3 from r5c4 because it is seen by all the 3's in Set A and Set B ie r136c4

This leaves just 8 in r5c4
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Clement



Joined: 24 Apr 2006
Posts: 1110
Location: Dar es Salaam Tanzania

PostPosted: Wed Mar 02, 2022 4:30 pm    Post subject: Evil 20220225 Reply with quote

Code:

+-----------------------+--------------------------+----------------------+
| 4       12569   1689  |  2369-8    689     7     | 2568    3589    2359 |
| 25789   25679   3     |  1         689     268   | 2568    589     4    |
| 289     269     689   | b23469-8   5      c23468 | 1       7       239  |
+-----------------------+--------------------------+----------------------+
| 12378   4       178   |  5         167-8  d136-8 | 9       13      1237 |
| 13789   1379    5     |ea348       2      d134-8 | 47      6       137  |
| 6       1237    17    |ea34        147     9     | 2457    1345    8    |
+-----------------------+--------------------------+----------------------+
| 1359    1359    2     |  7         1489    148   | 458     14589   6    |
| 179     1679    14679 |  469-8     3       5     | 478     2       179  |
| 1579    8       14679 |  2469      1469    1246  | 3       1459    1579 |
+-----------------------+--------------------------+----------------------+

Good solutions to TomC and Mogulmeister!
They can also be written as chain in compact form as
(8=3|4)56c4 – (4)r3c4 = (4-3)r3c6 = r45c6 – (3=8)r65c4 => - 8r138c4,r56c6,r5c6; lclste
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Mogulmeister



Joined: 03 May 2007
Posts: 1151

PostPosted: Thu Mar 03, 2022 7:31 am    Post subject: Reply with quote

👍 Nice
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