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Dec 19 VH

 
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ZeroAssoluto



Joined: 05 Feb 2017
Posts: 216
Location: Rimini, Italy

PostPosted: Mon Dec 18, 2017 11:12 pm    Post subject: Dec 19 VH Reply with quote

Hi everyone,

Code:

+------------+------------+--------------+
| 2   3  6   | 9   4  7   | 8    1   5   |
| 7   4  5   | 26  1  8   | 9    3   26  |
| 8   9  1   | 256 56 3   | 246  246 7   |
+------------+------------+--------------+
| 345 6  27  | 8   9  45  | 2347 24  1   |
| 45  1  278 | 567 3  456 | 2467 9   268 |
| 34  78 9   | 67  2  1   | 34   5   68  |
+------------+------------+--------------+
| 9   78 78  | 4   56 256 | 1    26  3   |
| 1   5  4   | 3   7  26  | 26   8   9   |
| 6   2  3   | 1   8  9   | 5    7   4   |
+------------+------------+--------------+

Play this puzzle online at the Daily Sudoku site

Quote:
XY-Chain in r4c3 -7- r6c2 -8- r6c9 -6- r2c9 -2- r2c4 -6- r3c5 -5- r7c5 -6- r7c8 and -2 in r4c8
or
XY-Chain: in r4c6 -4- r4c8 -2- r7c8 -6- r7c5 and -5 in r7c6


Ciao Gianni
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hughwill



Joined: 05 Apr 2010
Posts: 403
Location: Birmingham UK

PostPosted: Tue Dec 19, 2017 9:54 am    Post subject: Reply with quote

Unusual one using classic methods as one X wing
on 6 opens another X- wing on 6 before revealing
an XY-wing that sets it.

6 X wing- r26
6 X-wing- r57
45-2 XY wing pivot r4c6 r7c8<>2 stte

Hugh
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the_lock_man



Joined: 18 Dec 2012
Posts: 33
Location: Portsmarfff, UK

PostPosted: Tue Dec 19, 2017 12:15 pm    Post subject: Re: Dec 19 VH Reply with quote

Code:

+------------+------------+--------------+
| 2   3  6   | 9   4  7   | 8    1   5   |
| 7   4  5   | 26  1  8   | 9    3   26  |
| 8   9  1   | 256 56 3   | 246  246 7   |
+------------+------------+--------------+
| 345 6  27  | 8   9  45  | 2347 24  1   |
| 45  1  278 | 567 3  456 | 2467 9   268 |
| 34  78 9   | 67  2  1   | 34   5   68  |
+------------+------------+--------------+
| 9   78 78  | 4   56 256 | 1    26  3   |
| 1   5  4   | 3   7  26  | 26   8   9   |
| 6   2  3   | 1   8  9   | 5    7   4   |
+------------+------------+--------------+

Play this puzzle online at the Daily Sudoku site

My 6 X-Wing was in rows 3 & 7. This then opened a W-Wing on 24, boxes 3 & 6, meaning R6C7 <>4, then STTE.
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Earl



Joined: 30 May 2007
Posts: 589
Location: Victoria, KS

PostPosted: Tue Dec 19, 2017 2:47 pm    Post subject: Dec 19 VH Reply with quote

456xyzwing@R5C6: -5R5C4

Early Earl
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Marty R.



Joined: 12 Feb 2006
Posts: 5766
Location: Rochester, NY, USA

PostPosted: Tue Dec 19, 2017 7:47 pm    Post subject: Reply with quote

Hugh, that's very unusual for a puzzle to have three standard steps.

Based on previous posts, I'm unable to see the XYZ-Wing or an X-Wing (6) in rows 3 and 7.
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arkietech



Joined: 31 Jul 2008
Posts: 1825
Location: Northwest Arkansas USA

PostPosted: Tue Dec 19, 2017 11:30 pm    Post subject: Reply with quote

[(5=4)r4c6-(4=2)r4c8-r7c8=2r7c6]-5r7c6; ste
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immpy



Joined: 06 May 2017
Posts: 139

PostPosted: Fri Dec 22, 2017 11:18 am    Post subject: Reply with quote

I don't think there is an XYZ-Wing present on 456. The two supposed pincers are made up solely of bi-value 45. One of these bi-value cells should contain the 6 as a candidate, while remaining bi-value, in order for there to be an XYZ-Wing present.

The X-Wing on 6 alluded to in rows 3 and 7 is in the columns 5 and 8.
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mtharp



Joined: 19 Jun 2006
Posts: 30

PostPosted: Sat Mar 03, 2018 3:23 am    Post subject: Reply with quote

Folks, I am new to this, but it seems like there is an UR on 45 in r45c16 with diagonal candidates (3,6). I would like to solve this without using chains, which seems to me like trial and error.

I know it can be solved with X-wings.

Am hoping for a solution based on the UR.

immpy, your last instruction on URs was particularly helpful.

Code:

+------------+------------+--------------+
| 2   3  6   | 9   4  7   | 8    1   5   |
| 7   4  5   | 26  1  8   | 9    3   26  |
| 8   9  1   | 256 56 3   | 46   246 7   |
+------------+------------+--------------+
| 345 6  27  | 8   9  45  | 2347 24  1   |
| 45  1  278 | 567 3  456 | 2467 9   268 |
| 34  78 9   | 67  2  1   | 34   5   68  |
+------------+------------+--------------+
| 9   78 78  | 4   56 256 | 1    26  3   |
| 1   5  4   | 3   7  26  | 26   8   9   |
| 6   2  3   | 1   8  9   | 5    7   4   |
+------------+------------+--------------+

Play this puzzle online at the Daily Sudoku site

Mike
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Marty R.



Joined: 12 Feb 2006
Posts: 5766
Location: Rochester, NY, USA

PostPosted: Sat Mar 03, 2018 6:08 am    Post subject: Reply with quote

mtharp wrote:
Folks, I am new to this, but it seems like there is an UR on 45 in r45c16 with diagonal candidates (3,6). I would like to solve this without using chains, which seems to me like trial and error.

I know it can be solved with X-wings.

Am hoping for a solution based on the UR.

immpy, your last instruction on URs was particularly helpful.

Code:

+------------+------------+--------------+
| 2   3  6   | 9   4  7   | 8    1   5   |
| 7   4  5   | 26  1  8   | 9    3   26  |
| 8   9  1   | 256 56 3   | 46   246 7   |
+------------+------------+--------------+
| 345 6  27  | 8   9  45  | 2347 24  1   |
| 45  1  278 | 567 3  456 | 2467 9   268 |
| 34  78 9   | 67  2  1   | 34   5   68  |
+------------+------------+--------------+
| 9   78 78  | 4   56 256 | 1    26  3   |
| 1   5  4   | 3   7  26  | 26   8   9   |
| 6   2  3   | 1   8  9   | 5    7   4   |
+------------+------------+--------------+

Play this puzzle online at the Daily Sudoku site

Mike


Well, the 6 in r5c6 proves a 3 in r6c7=> -3r4c7,r6c1
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mtharp



Joined: 19 Jun 2006
Posts: 30

PostPosted: Sat Mar 03, 2018 8:07 am    Post subject: Reply with quote

Marty, thanks.

You wrote:

Well, the 6 in r5c6 proves a 3 in r6c7=> -3r4c7,r6c1

If you would, please help me understand your logic outside of using a trial and error chain.

Again thanks for the response. Sorry to be so dense.

Mike
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immpy



Joined: 06 May 2017
Posts: 139

PostPosted: Sat Mar 03, 2018 9:36 am    Post subject: Reply with quote

Hello Mike, and thanks for your nice comment. I am just beginning to grasp some of these variations on the UR myself, so I will do my best to explain with my (limited) knowledge.

Sadly, I don't think this one will fit into any of the 6 UR patterns, based on what I understand at this point.

It is ALMOST a Type 6 UR (45) with the extra (non UR) candidates being diagonal from each other.....BUT....EITHER the 4 OR the 5 would have to be the only possibilities for BOTH of their rows AND columns in order for the Type 6 UR to be present. The 4 and 5 simply occur too often in both of the rows and columns of this rectangle.

But IF it would have been present, a Type 6 UR not only eliminates one of the candidates (in this case either 4 or 5) from both of the cells which contain the extra non-UR candidates, it results in TWO placements, as well. In this case both of the bi-value cells of 45 (which make up the opposite diagonal) would become either the 4 or the 5, based on what we eliminated from the cells with the extra candidates.

That's a lot to think about....but I hope the bulb is becoming illuminated.
Thanks again Mike.

cheers.....immp
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mtharp



Joined: 19 Jun 2006
Posts: 30

PostPosted: Sat Mar 03, 2018 3:01 pm    Post subject: Reply with quote

immp, thanks for the type 6 UR lesson. It is starting to make sense. The operative word being "starting".

Is there another way to tackle this UR without using chains?

Mike
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Marty R.



Joined: 12 Feb 2006
Posts: 5766
Location: Rochester, NY, USA

PostPosted: Sat Mar 03, 2018 3:47 pm    Post subject: Reply with quote

mtharp wrote:
Marty, thanks.

You wrote:

Well, the 6 in r5c6 proves a 3 in r6c7=> -3r4c7,r6c1

If you would, please help me understand your logic outside of using a trial and error chain.

Again thanks for the response. Sorry to be so dense.

Mike


Well, Mike, trial and error is a debatable concept, I understand that chains can be T&E because you start out not knowing where you're going. Many puzzles are not solvable by pattern-based solutions and chains are used by numerous advanced players (myself not included).

The logic is that we must have a 3 or 6. If it's 6, then r6c7 is 3, If not 6, then r4c1 is 3. Both r6c7 and r4c1 see the cells from which the eliminations are made.
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immpy



Joined: 06 May 2017
Posts: 139

PostPosted: Sun Mar 04, 2018 12:54 am    Post subject: Reply with quote

Sorry Mike, there is no UR present (on 45) to be tackled. Those X-wings you mentioned knowing about (I believe there are two of them on the 6) do just fine on their own. Sometimes a technique we favor is simply not present, no matter how close it may appear to being one.
Interestingly, there is a Type 5 UR (on34) r46c17 with extra candidates occurring in the two cells in r4. As per the Type 5 UR parameters the 3s occur in ONLY the four cells that make up the UR, so the 4s could be eliminated from the two cells with extra candidates in r4 which comprise the UR. But that only results in two eliminations, which lead to nothing else, and one would still need the X-wings on 6 to solve the puzzle. An example of a fruitless UR, one could say. I would ignore this one, anyway, as it seems vague, at best.

cheers...immp
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Marty R.



Joined: 12 Feb 2006
Posts: 5766
Location: Rochester, NY, USA

PostPosted: Sun Mar 04, 2018 2:25 am    Post subject: Reply with quote

Quote:
It is ALMOST a Type 6 UR (45) with the extra (non UR) candidates being diagonal from each other.....BUT....EITHER the 4 OR the 5 would have to be the only possibilities for BOTH of their rows AND columns in order for the Type 6 UR to be present. The 4 and 5 simply occur too often in both of the rows and columns of this rectangle.


Just to change the wording slightly, with a Type 6 one of the deadly candidates needs to be an X-Wing. The eliminations from a Type 6 seldom make a worthwhile dent in the puzzle.
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mtharp



Joined: 19 Jun 2006
Posts: 30

PostPosted: Sun Mar 04, 2018 3:51 am    Post subject: Reply with quote

immp & Marty, I really appreciate the time you folks spend bringing us slow folks up to speed.

Thank you both.

Mike
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Marty R.



Joined: 12 Feb 2006
Posts: 5766
Location: Rochester, NY, USA

PostPosted: Sun Mar 04, 2018 4:30 am    Post subject: Reply with quote

mtharp wrote:
immp & Marty, I really appreciate the time you folks spend bringing us slow folks up to speed.

Thank you both.

Mike


I learned everything I know (not nearly enough) on his forum and I 'm happy to pay it forward.
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