View previous topic :: View next topic 
Author 
Message 
Clement
Joined: 24 Apr 2006 Posts: 819 Location: Dar es Salaam Tanzania

Posted: Sun Nov 24, 2013 11:45 pm Post subject: Nov 25 VH 


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 
++++
 WWing 26 in BOX 19 with SL 2 in row 1; r7c3<>6 opens single's chains on 4; r8c8<>4; stte. 

Back to top 


roaa
Joined: 18 Apr 2009 Posts: 110 Location: Sweden

Posted: Mon Nov 25, 2013 10:16 am Post subject: Nov 25 VH 


An xywing (269) opens up a new xywing (249) which solves it. 

Back to top 


hughwill
Joined: 05 Apr 2010 Posts: 333 Location: Birmingham UK

Posted: Mon Nov 25, 2013 10:59 am Post subject: Nov 25 VH 


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 

Back to top 


Marty R.
Joined: 12 Feb 2006 Posts: 5466 Location: Rochester, NY, USA

Posted: Mon Nov 25, 2013 11:51 am Post subject: 


I also used the two XYWings. These are much more fun when they're not onesteppers. 

Back to top 


yeoks
Joined: 16 May 2010 Posts: 31

Posted: Mon Nov 25, 2013 12:28 pm Post subject: Nov 25 VH 


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

Back to top 


George Woods
Joined: 28 Mar 2006 Posts: 270 Location: Dorset UK

Posted: Wed Nov 27, 2013 8:33 pm Post subject: Chain of 46 single step 


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 

Back to top 


Marty R.
Joined: 12 Feb 2006 Posts: 5466 Location: Rochester, NY, USA

Posted: Wed Nov 27, 2013 10:46 pm Post subject: Re: Chain of 46 single step 


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. 

Back to top 


Marty R.
Joined: 12 Feb 2006 Posts: 5466 Location: Rochester, NY, USA

Posted: Thu Nov 28, 2013 1:06 am Post subject: Re: Chain of 46 single step 


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 TF or FT.
However, you said you set r8c5=4 but the coloring says it's <>4. 

Back to top 


George Woods
Joined: 28 Mar 2006 Posts: 270 Location: Dorset UK

Posted: Thu Nov 28, 2013 11:34 am Post subject: colouring of 4s 


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 

Back to top 


Jeff
Joined: 06 May 2007 Posts: 40

Posted: Fri Nov 29, 2013 4:48 am Post subject: Re: Nov 25 VH 


roaa wrote:  An xywing (269) opens up a new xywing (249) which solves it.  .
I think I see the 269 xywing 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 xywing and would appreciate some comments. Maybe I am missing something obvious. Thanks. 

Back to top 


Marty R.
Joined: 12 Feb 2006 Posts: 5466 Location: Rochester, NY, USA

Posted: Fri Nov 29, 2013 5:15 am Post subject: Re: Nov 25 VH 


Jeff wrote:  roaa wrote:  An xywing (269) opens up a new xywing (249) which solves it.  .
I think I see the 269 xywing 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 xywing 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. 

Back to top 


Jeff
Joined: 06 May 2007 Posts: 40

Posted: Fri Nov 29, 2013 4:03 pm Post subject: Re: Nov 25 VH 


Marty R. wrote:  Jeff wrote:  roaa wrote:  An xywing (269) opens up a new xywing (249) which solves it.  .
I think I see the 269 xywing 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 xywing 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 

Back to top 


