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chicago tribune 2/9/18 DS too hard

 
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mtharp



Joined: 19 Jun 2006
Posts: 18

PostPosted: Sat Feb 10, 2018 2:49 pm    Post subject: chicago tribune 2/9/18 DS too hard Reply with quote

Folks, I am stuck again. Any pattern help appreciated.

Mike

Code:

+--------------+-----------------+---------------+
| 56 1    2579 | 457   4567 47   | 24679 8   3   |
| 4  2378 2578 | 9     5678 378  | 267   27  1   |
| 36 378  789  | 3478  1    2    | 4679  479 5   |
+--------------+-----------------+---------------+
| 9  48   3    | 478   2    478  | 5     1   6   |
| 1  248  248  | 6     3    5    | 478   47  9   |
| 7  5    6    | 48    9    1    | 248   3   24  |
+--------------+-----------------+---------------+
| 8  6    457  | 1     457  9    | 3     245 247 |
| 35 347  1457 | 2     457  6    | 149   459 8   |
| 2  9    1457 | 34578 4578 3478 | 14    6   47  |
+--------------+-----------------+---------------+

Play this puzzle online at the Daily Sudoku site
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Marty R.



Joined: 12 Feb 2006
Posts: 5731
Location: Rochester, NY, USA

PostPosted: Sat Feb 10, 2018 4:48 pm    Post subject: Re: chicago tribune 2/9/18 DS too hard Reply with quote

mtharp wrote:
Folks, I am stuck again. Any pattern help appreciated.

Mike

Code:

+--------------+-----------------+---------------+
| 56 1    2579 | 457   4567 47   | 24679 8   3   |
| 4  2378 2578 | 9     5678 378  | 267   27  1   |
| 36 378  789  | 3478  1    2    | 4679  479 5   |
+--------------+-----------------+---------------+
| 9  48   3    | 478   2    478  | 5     1   6   |
| 1  248  248  | 6     3    5    | 478   47  9   |
| 7  5    6    | 48    9    1    | 248   3   24  |
+--------------+-----------------+---------------+
| 8  6    457  | 1     457  9    | 3     245 247 |
| 35 347  1457 | 2     457  6    | 149   459 8   |
| 2  9    1457 | 34578 4578 3478 | 14    6   47  |
+--------------+-----------------+---------------+

Play this puzzle online at the Daily Sudoku site


There's a Skyscraper (5) in c14. It makes two eliminations, one of which is -5r9c3, after which there are locked candidates, with the 5s in r9 confined to b8.
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ZeroAssoluto



Joined: 05 Feb 2017
Posts: 195
Location: Rimini, Italy

PostPosted: Sat Feb 10, 2018 5:02 pm    Post subject: Reply with quote

Hi Mike,

first step: pair 2,9 in r1c37.

Later it becomes more complicated.
Eventually we resent for other steps.

Ciao Gianni
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Marty R.



Joined: 12 Feb 2006
Posts: 5731
Location: Rochester, NY, USA

PostPosted: Sat Feb 10, 2018 5:39 pm    Post subject: Reply with quote

ZeroAssoluto wrote:
Hi Mike,

first step: pair 2,9 in r1c37.

Later it becomes more complicated.
Eventually we resent for other steps.

Ciao Gianni


I agree, but I'd have stated it differently. That doesn't mean I'm right, it's just personal preference. I never paid much attention to hidden pairs because for every hidden pair or triple there's a complementary subset. In this case it's a 4567 quad and that's how I would've stated it had I noticed (shame on me).
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immpy



Joined: 06 May 2017
Posts: 116

PostPosted: Sat Feb 10, 2018 6:06 pm    Post subject: Reply with quote

Yes, first thing was the hidden quad/pair in row 1. (29) (4567)
Then the skyscraper (5). Both of these were noted. Follow this with a good thorough rinsing for box/line eliminations. That helped me to arrive here:

Code:

+--------------+-------------+--------------+
| 56 1    29   | 47  56  47  | 29   8   3   |
| 4  2378 2578 | 9   568 378 | 267  27  1   |
| 36 378  789  | 378 1   2   | 4679 479 5   |
+--------------+-------------+--------------+
| 9  48   3    | 478 2   478 | 5    1   6   |
| 1  248  248  | 6   3   5   | 478  47  9   |
| 7  5    6    | 48  9   1   | 248  3   24  |
+--------------+-------------+--------------+
| 8  6    457  | 1   47  9   | 3    245 247 |
| 35 347  1457 | 2   47  6   | 149  459 8   |
| 2  9    147  | 358 58  38  | 14   6   47  |
+--------------+-------------+--------------+

Play this puzzle online at the Daily Sudoku site

I then noticed a UR (47) r14c46, with 8 as the extra candidate on the common side of r4. Thus r4c2<>8(=4) and r6c4<>8(=4). That should solve it quite nicely. These coordinates can also be played as an X-Wing on 7 which results in some good eliminations as well. r2c6<>7 and r3c4<>7.

cheers...immp
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Marty R.



Joined: 12 Feb 2006
Posts: 5731
Location: Rochester, NY, USA

PostPosted: Sat Feb 10, 2018 10:28 pm    Post subject: Reply with quote

Quote:
I then noticed a UR (47) r14c46, with 8 as the extra candidate on the common side of r4


Yes, that's an example of a Type 2 UR.
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mtharp



Joined: 19 Jun 2006
Posts: 18

PostPosted: Sun Feb 11, 2018 1:56 pm    Post subject: Reply with quote

Folks, I appreciate the help.

Thanks.

Mike
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Ajò Dimonios



Joined: 01 May 2017
Posts: 299
Location: Sassari Italy

PostPosted: Sun Feb 11, 2018 11:21 pm    Post subject: Reply with quote

Hi everyone

This scheme can be solved with just one step after basics using the technique de pistes de Robert Mauriès. The trace R1C3 = 2 is certainly false because it produces a contradiction. After elimination of the 2 in R1C3 the solution is easily reached.

Ciao a Tutti
Paolo
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