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NO silliness...a Very Hard

 
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immpy



Joined: 06 May 2017
Posts: 199

PostPosted: Fri Mar 02, 2018 2:41 pm    Post subject: NO silliness...a Very Hard Reply with quote

Drop this one on the Draw/Play and grade it for yourself.
A Very Hard Puzzle...proceed accordingly...and enjoy the puzzle....

Code:

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

Play this puzzle online at the Daily Sudoku site

cheers...immp
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keith



Joined: 19 Sep 2005
Posts: 3340
Location: near Detroit, Michigan, USA

PostPosted: Fri Mar 02, 2018 3:47 pm    Post subject: Reply with quote

Multi-step, fishy thing.

Keith
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AjÚ Dimonios



Joined: 01 May 2017
Posts: 325
Location: Sassari Italy

PostPosted: Fri Mar 02, 2018 6:23 pm    Post subject: Reply with quote

Hi everyone

Code:

+----------------+------------+---------------+
| 9    6    1    | 8   3   7  | 5    4    2   |
| 257  25   3    | 6   4   29 | 1    789  89  |
| 8    24   247  | 1   29  5  | 6    79   3   |
+----------------+------------+---------------+
| 24   1    6    | 9   5   8  | 24   3    7   |
| 3457 9    4578 | 347 27  24 | 48   6    1   |
| 2347 2348 2478 | 347 1   6  | 2489 589  589 |
+----------------+------------+---------------+
| 6    7    89   | 5   89  1  | 3    2    4   |
| 1235 2358 2589 | 47  789 49 | 89   1589 6   |
| 145  458  4589 | 2   6   3  | 7    1589 589 |
+----------------+------------+---------------+

Play this puzzle online at the Daily Sudoku site

Solution with one move.

[9R7C5-(9=2)R3C5-(2=4)R3C2; 9R7C5-(9=8)R7C3-8R9C2; (9-8)R7C5=8R8C5-(8=9)R8C7-9R9C9 and 9R7C5-9R3C5=9R2C6-(9=8)R2C9-(8=5)R9C9-(5=4)R9C2]=>contradiction (two certain 4 in column 2)=>-9R7C5=>Stte.
Ciao a Tutti
Paolo
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ZeroAssoluto



Joined: 05 Feb 2017
Posts: 296
Location: Rimini, Italy

PostPosted: Fri Mar 02, 2018 7:47 pm    Post subject: Reply with quote

Hi everyone,

after basic

Code:

+----------------+------------+---------------+
| 9    6    1    | 8   3   7  | 5    4    2   |
| 257  25   3    | 6   4   29 | 1    789  89  |
| 8    24   247  | 1   29  5  | 6    79   3   |
+----------------+------------+---------------+
| 24   1    6    | 9   5   8  | 24   3    7   |
| 3457 9    4578 | 347 27  24 | 48   6    1   |
| 2347 2348 2478 | 347 1   6  | 2489 589  589 |
+----------------+------------+---------------+
| 6    7    89   | 5   89  1  | 3    2    4   |
| 1235 235  25   | 47  789 49 | 89   15   6   |
| 145  458  4589 | 2   6   3  | 7    1589 589 |
+----------------+------------+---------------+

Play this puzzle online at the Daily Sudoku site

XY-Chain r8c4 7,4 - r8c6 4,9 - r8c7 9,8 - r5c7 8,4 - r5c6 4,2 - r5c5 2,7 and -7 in r56c4,r8c5.

and

Code:

+---------------+---------+-------------+
| 9    6   1    | 8  3  7 | 5    4   2  |
| 25   25  3    | 6  4  9 | 1    7   8  |
| 8    4   7    | 1  2  5 | 6    9   3  |
+---------------+---------+-------------+
| 24   1   6    | 9  5  8 | 24   3   7  |
| 345  9   458  | 34 7  2 | 48   6   1  |
| 7    238 248  | 34 1  6 | 2489 58  59 |
+---------------+---------+-------------+
| 6    7   89   | 5  89 1 | 3    2   4  |
| 1235 235 25   | 7  89 4 | 89   15  6  |
| 145  58  4589 | 2  6  3 | 7    158 59 |
+---------------+---------+-------------+

Play this puzzle online at the Daily Sudoku site

XY-Wing 5,8,9 in r8c7,r9c29 and -8 in r9c8.

Ciao Gianni
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immpy



Joined: 06 May 2017
Posts: 199

PostPosted: Sat Mar 03, 2018 8:33 am    Post subject: Reply with quote

For myself, it was as easy as saying, "Bartender, make it a double."
A double XY-wing, that is.
Look at Paolo's first post after basics. (scroll up)
There is a -489 XY-wing r58c67 pivoted @ r8c7.
This results in an elimination of r5c6<>4 (=2)!
And a good rinsing takes you almost half way through, which
brings us here:


Code:

+---------------+---------+-------------+
| 9    6   1    | 8  3  7 | 5    4   2  |
| 25   25  3    | 6  4  9 | 1    7   8  |
| 8    4   7    | 1  2  5 | 6    9   3  |
+---------------+---------+-------------+
| 24   1   6    | 9  5  8 | 24   3   7  |
| 345  9   458  | 34 7  2 | 48   6   1  |
| 7    238 248  | 34 1  6 | 2489 58  59 |
+---------------+---------+-------------+
| 6    7   89   | 5  89 1 | 3    2   4  |
| 1235 235 25   | 7  89 4 | 89   15  6  |
| 145  58  4589 | 2  6  3 | 7    158 59 |
+---------------+---------+-------------+

Play this puzzle online at the Daily Sudoku site

The second XY-wing is then the 58-9 r7c3 & r9c29 pivoted @ r9c2.
This results in an elimination of r9c3<>9...and solves the puzzle, as it did for Gianni, when he arrived here, as well.


cheers...imp

I LOVE multi-step VHs...!
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