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Nov 25 VH

 
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Clement



Joined: 24 Apr 2006
Posts: 639
Location: Dar es Salaam Tanzania

PostPosted: Sun Nov 24, 2013 11:45 pm    Post subject: Nov 25 VH Reply with quote

Code:

+-------------+---------+--------------+
| *26   5  7   | 3  9  8 | 1     *246 46 |
| 49   1  49  | 7  2  6 | 3     8   5  |
| 8    3  #26  | 5  1  4 | 26    7   9  |
+-------------+---------+--------------+
| 1    29 29  | 46 3  7 | 8     5   46 |
| 7    8  3   | 1  46 5 | 46    9   2  |
| 45   6  45  | 2  8  9 | 7     3   1  |
+-------------+---------+--------------+
| 3    4  25-6 | 9  7  1 | 256   #26  8  |
| 2569 29 1   | 8  46 3 | 24569 2-46 7  |
| 69   7  8   | 46 5  2 | 469   1   3  |
+-------------+---------+--------------+
W-Wing 26 in BOX 19 with SL 2 in row 1; r7c3<>6 opens single's chains on 4; r8c8<>4; stte.
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roaa



Joined: 18 Apr 2009
Posts: 65
Location: Sweden

PostPosted: Mon Nov 25, 2013 10:16 am    Post subject: Nov 25 VH Reply with quote

An xy-wing (269) opens up a new xy-wing (249) which solves it.
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hughwill



Joined: 05 Apr 2010
Posts: 141
Location: Birmingham UK

PostPosted: Mon Nov 25, 2013 10:59 am    Post subject: Nov 25 VH Reply with quote

After basics:
Code:

+-------------+---------+--------------+
| 26   5  7   | 3  9  8 | 1     246 46 |
| 49   1  49  | 7  2  6 | 3     8   5  |
| 8    3  26  | 5  1  4 | 26    7   9  |
+-------------+---------+--------------+
| 1    29 29  | 46 3  7 | 8     5   46 |
| 7    8  3   | 1  46 5 | 46    9   2  |
| 45   6  45  | 2  8  9 | 7     3   1  |
+-------------+---------+--------------+
| 3    4  256 | 9  7  1 | 256   26  8  |
| 2569 29 1   | 8  46 3 | 24569 246 7  |
| 69   7  8   | 46 5  2 | 469   1   3  |
+-------------+---------+--------------+

Play this puzzle online at the Daily Sudoku site

Or taking a piece of both solutions: By removing the 6's in r89 in box 9
Clement's W wing leads to roaa's second (249) XY wing. I found this one
very hard to see today for some reason......

Hugh
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Marty R.



Joined: 12 Feb 2006
Posts: 5061
Location: Rochester, NY, USA

PostPosted: Mon Nov 25, 2013 11:51 am    Post subject: Reply with quote

I also used the two XY-Wings. These are much more fun when they're not one-steppers.
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yeoks



Joined: 16 May 2010
Posts: 16

PostPosted: Mon Nov 25, 2013 12:28 pm    Post subject: Nov 25 VH Reply with quote

I used Remote Pairs (46) in r5c7 and r9c4 which solves it
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George Woods



Joined: 28 Mar 2006
Posts: 231
Location: Dorset UK

PostPosted: Wed Nov 27, 2013 8:33 pm    Post subject: Chain of 46 single step Reply with quote

Taking Clements position and ignoring the w Wing I posited r8c8 as 4 and via r1c9 = 4 went through all the 46s leading to r8c5 being 4. Hence r8c8 cannot be 4 so r1c8 must be 4 which solves the puzzle.

I was not very happy with this solution as it smacked of trial and error, but wonder if it is equivalent to colouring 4. Can anyone tell me?


Last edited by George Woods on Wed Nov 27, 2013 10:27 pm; edited 1 time in total
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Marty R.



Joined: 12 Feb 2006
Posts: 5061
Location: Rochester, NY, USA

PostPosted: Wed Nov 27, 2013 10:46 pm    Post subject: Re: Chain of 46 single step Reply with quote

George Woods wrote:
Taking Clements position and ignoring the w Wing I posited r8c8 as 4 and via r1c9 = 4 went through all the 46s leading to r8c5 being 4. Hence r8c8 cannot be 4 so r1c8 must be 4 which solves the puzzle.

I was not very happy with this solution as it smacked of trial and error, but wonder if it is equivalent to colouring 4. Can anyone tell me?


I don't know what you did to set r8c5=4, but once that is done, you don't need the hence.... It solves from that initial setting of 4. The "hence" part is redundant since it occurs automatically as part of the cleaning up process.
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Marty R.



Joined: 12 Feb 2006
Posts: 5061
Location: Rochester, NY, USA

PostPosted: Thu Nov 28, 2013 1:06 am    Post subject: Re: Chain of 46 single step Reply with quote

Marty R. wrote:
George Woods wrote:
Taking Clements position and ignoring the w Wing I posited r8c8 as 4 and via r1c9 = 4 went through all the 46s leading to r8c5 being 4. Hence r8c8 cannot be 4 so r1c8 must be 4 which solves the puzzle.

I was not very happy with this solution as it smacked of trial and error, but wonder if it is equivalent to colouring 4. Can anyone tell me?


I don't know what you did to set r8c5=4, but once that is done, you don't need the hence.... It solves from that initial setting of 4. The "hence" part is redundant since it occurs automatically as part of the cleaning up process.


Here's what I did with the 4s.

Code:
+-------------+-----------+----------------+
| 26   5  7   |  3   9  8 | 1     B246 C46 |
| 49   1  49  |  7   2  6 | 3      8    5  |
| 8    3  26  |  5   1  4 | 26     7    9  |
+-------------+-----------+----------------+
| 1    29 29  | E46  3  7 | 8      5   D46 |
| 7    8  3   |  1  F46 5 | 46     9    2  |
| 45   6  45  |  2   8  9 | 7      3    1  |
+-------------+-----------+----------------+
| 3    4  256 |  9   7  1 | 256    26   8  |
| 2569 29 1   |  8   46 3 | 24569 A246  7  |
| 69   7  8   |  46  5  2 | 469    1    3  |
+-------------+-----------+----------------+


Going from A to F or F to A, that is classic coloring, with an even number of cells and the start and end of the chain being T-F or F-T.

However, you said you set r8c5=4 but the coloring says it's <>4.
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George Woods



Joined: 28 Mar 2006
Posts: 231
Location: Dorset UK

PostPosted: Thu Nov 28, 2013 11:34 am    Post subject: colouring of 4s Reply with quote

My explanation maybe wasn't clear. What I might have said is that r8c8 cannot be 4, because if it were it leads to r8c5 being 4 also ---- and that is not valid hence r8c8 cannot be 4 and since r8c8 cannot be 4 the value of r8c5 is unknown as yet but the value of r1c8 is now kown to be 4 and the puzzle falls out
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Jeff



Joined: 06 May 2007
Posts: 30

PostPosted: Fri Nov 29, 2013 4:48 am    Post subject: Re: Nov 25 VH Reply with quote

roaa wrote:
An xy-wing (269) opens up a new xy-wing (249) which solves it.
.

I think I see the 269 xy-wing with c1r9 (69), c2r8(29), and c1r1(26). This eliminates the 2 in c1r8, which does not seem to make much progress. I certainly can't find the 249 xy-wing and would appreciate some comments. Maybe I am missing something obvious. Thanks.
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Marty R.



Joined: 12 Feb 2006
Posts: 5061
Location: Rochester, NY, USA

PostPosted: Fri Nov 29, 2013 5:15 am    Post subject: Re: Nov 25 VH Reply with quote

Jeff wrote:
roaa wrote:
An xy-wing (269) opens up a new xy-wing (249) which solves it.
.

I think I see the 269 xy-wing with c1r9 (69), c2r8(29), and c1r1(26). This eliminates the 2 in c1r8, which does not seem to make much progress. I certainly can't find the 249 xy-wing and would appreciate some comments. Maybe I am missing something obvious. Thanks.


Removing that 2 from r8c1 leaves r1c1 as the only remaining 2 in c1. Carrying on from there exposes the 249 Wing. Pay careful attention to the 6s in c1 and r7.
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Jeff



Joined: 06 May 2007
Posts: 30

PostPosted: Fri Nov 29, 2013 4:03 pm    Post subject: Re: Nov 25 VH Reply with quote

Marty R. wrote:
Jeff wrote:
roaa wrote:
An xy-wing (269) opens up a new xy-wing (249) which solves it.
.

I think I see the 269 xy-wing with c1r9 (69), c2r8(29), and c1r1(26). This eliminates the 2 in c1r8, which does not seem to make much progress. I certainly can't find the 249 xy-wing and would appreciate some comments. Maybe I am missing something obvious. Thanks.


Removing that 2 from r8c1 leaves r1c1 as the only remaining 2 in c1. Carrying on from there exposes the 249 Wing. Pay careful attention to the 6s in c1 and r7.


Thank you so much. Somehow, I missed those key points. Jeff
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