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Apr 30 VH

 
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ZeroAssoluto



Joined: 05 Feb 2017
Posts: 517
Location: Rimini, Italy

PostPosted: Thu Apr 30, 2020 7:38 am    Post subject: Apr 30 VH Reply with quote

Hi everyone,

Code:

+-----------+-------------+-----------+
| 9  37  68 | 167 38  4   | 16  2  5  |
| 2  1   4  | 679 5   379 | 8   37 69 |
| 37 5   68 | 169 89  2   | 169 37 4  |
+-----------+-------------+-----------+
| 1  2   5  | 4   7   6   | 3   9  8  |
| 4  8   9  | 3   2   5   | 67  1  67 |
| 36 36  7  | 8   19  19  | 5   4  2  |
+-----------+-------------+-----------+
| 8  679 1  | 2   369 379 | 4   5  79 |
| 5  79  3  | 79  4   8   | 2   6  1  |
| 67 4   2  | 5   169 179 | 79  8  3  |
+-----------+-------------+-----------+

Play this puzzle online at the Daily Sudoku site

UR 1,9 in r69c56 and -9 in r9c56

Code:

+----------+-----------+---------+
| 9  37 68 | 17 38  4  | 16 2  5 |
| 2  1  4  | 6  5   37 | 8  37 9 |
| 37 5  68 | 19 89  2  | 16 37 4 |
+----------+-----------+---------+
| 1  2  5  | 4  7   6  | 3  9  8 |
| 4  8  9  | 3  2   5  | 7  1  6 |
| 36 36 7  | 8  19  19 | 5  4  2 |
+----------+-----------+---------+
| 8  69 1  | 2  369 39 | 4  5  7 |
| 5  79 3  | 79 4   8  | 2  6  1 |
| 67 4  2  | 5  16  17 | 9  8  3 |
+----------+-----------+---------+

Play this puzzle online at the Daily Sudoku site

XY-Wing 3,7,9 in r27c6,r8c4 and -7 in r1c4,r9c6

or with only one step
AIC in r1c2
if ric2=7 -7 in r3c1,r78c2
if ric2=3 r7c5=3 r7c2=6 r9c1=7 and -7 in r3c1,r78c2

Ciao Gianni
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the_lock_man



Joined: 18 Dec 2012
Posts: 39
Location: Portsmarfff, UK

PostPosted: Thu Apr 30, 2020 11:53 am    Post subject: Reply with quote

Sorry, Gianni, I don't get your logic there at all. I don't understand where the 9 in r2c6 disappears to in between your two steps.

The way I solved it is

Code:

+-----------+-------------+-----------+
| 9  37  68 | 167 38  4   | 16  2  5  |
| 2  1   4  | 679 5   379 | 8   37 69 |
| 37 5   68 | 169 89  2   | 169 37 4  |
+-----------+-------------+-----------+
| 1  2   5  | 4   7   6   | 3   9  8  |
| 4  8   9  | 3   2   5   | 67  1  67 |
| 36 36  7  | 8   19  19  | 5   4  2  |
+-----------+-------------+-----------+
| 8  679 1  | 2   369 37  | 4   5  79 |
| 5  79  3  | 79  4   8   | 2   6  1  |
| 67 4   2  | 5   169 179 | 79  8  3  |
+-----------+-------------+-----------+

Play this puzzle online at the Daily Sudoku site

X wing on 7s in rows 1 & 8, cols 2 & 4 removes 7 in R7C2 (& R2C4). This then reveals an XY wing 679, pivot R7C2, -9 in R7C9, then STTE.
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ZeroAssoluto



Joined: 05 Feb 2017
Posts: 517
Location: Rimini, Italy

PostPosted: Thu Apr 30, 2020 12:36 pm    Post subject: Reply with quote

Hi the_lock_man,

the reasoning is as follows:
in R9c56 you cannot have the number 1 and 9 at the same time, but the number 1 in sector 8 can only be in one of the two cells, so even if you do not know in which cell it is located you can be sure that not there will also be the number 9 and at this point it remains only in r9c7.
I hope I have been clear even though I don't speak english very well.

Ciao Gianni
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ZeroAssoluto



Joined: 05 Feb 2017
Posts: 517
Location: Rimini, Italy

PostPosted: Thu Apr 30, 2020 1:01 pm    Post subject: Reply with quote

Another reasoning can be followed: in r9c56 there will certainly be either the number 6 or the number 7; one of these combined with r9c1 leaves only the number 9 as a possibility for r9c7.

Ciao Gianni
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dongrave



Joined: 06 Mar 2014
Posts: 363

PostPosted: Thu Apr 30, 2020 2:02 pm    Post subject: Reply with quote

the_lock_man wrote:
Sorry, Gianni, I don't get your logic there at all. I don't understand where the 9 in r2c6 disappears to in between your two steps.

The way I solved it is

Code:

+-----------+-------------+-----------+
| 9  37  68 | 167 38  4   | 16  2  5  |
| 2  1   4  | 679 5   379 | 8   37 69 |
| 37 5   68 | 169 89  2   | 169 37 4  |
+-----------+-------------+-----------+
| 1  2   5  | 4   7   6   | 3   9  8  |
| 4  8   9  | 3   2   5   | 67  1  67 |
| 36 36  7  | 8   19  19  | 5   4  2  |
+-----------+-------------+-----------+
| 8  679 1  | 2   369 37  | 4   5  79 |
| 5  79  3  | 79  4   8   | 2   6  1  |
| 67 4   2  | 5   169 179 | 79  8  3  |
+-----------+-------------+-----------+

Play this puzzle online at the Daily Sudoku site

X wing on 7s in rows 1 & 8, cols 2 & 4 removes 7 in R7C2 (& R2C4). This then reveals an XY wing 679, pivot R7C2, -9 in R7C9, then STTE.


I also used the 7 X-wing that lock_man used and then the 679 XY-wing that he mentioned (except that the 69-7 XY with pivot at r7c2 gives -7 in r9c7 or alternatively the 67-9 XY with pivot at r9c1 gives -9 in r7c9) but then I also needed a 39-7 XY with pivot at r7c6 giving -7 in r1c4 and r9c6 to solve it! I don't think the X wing followed by the first XY wing solved it. Don.
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ZeroAssoluto



Joined: 05 Feb 2017
Posts: 517
Location: Rimini, Italy

PostPosted: Thu Apr 30, 2020 7:17 pm    Post subject: Reply with quote

the_lock_man wrote:
Sorry, Gianni, I don't get your logic there at all. I don't understand where the 9 in r2c6 disappears to in between your two steps.



Sorry, I left a part
when r9c7 = 9 in column 9 the only 9 is in r2c9 and -9 in r2c6

Ciao Gianni
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