dailysudoku.com Forum Index dailysudoku.com
Discussion of Daily Sudoku puzzles
 
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

Helmut's Feb 18 Advanced

 
Post new topic   Reply to topic    dailysudoku.com Forum Index -> Other puzzles
View previous topic :: View next topic  
Author Message
keith



Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA

PostPosted: Fri Feb 19, 2016 1:56 am    Post subject: Helmut's Feb 18 Advanced Reply with quote

Enjoyed this one:

Code:

+-----------+-----------+-----------+
|  3  .  8  |  .  4  .  |  .  .  1  |
|  .  1  .  |  .  .  .  |  .  2  .  |
|  .  .  .  |  8  5  .  |  .  .  .  |
+-----------+-----------+-----------+
|  5  .  .  |  9  1  .  |  8  .  .  |
|  .  .  1  |  .  3  .  |  2  .  .  |
|  .  .  3  |  .  7  4  |  .  .  6  |
+-----------+-----------+-----------+
|  .  .  .  |  .  9  7  |  .  .  .  |
|  .  4  .  |  .  .  .  |  .  5  .  |
|  1  .  .  |  .  2  .  |  3  .  9  |
+-----------+-----------+-----------+
Back to top
View user's profile Send private message
Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA

PostPosted: Fri Feb 19, 2016 2:57 am    Post subject: Reply with quote

Code:

+------------+-------+---------+
| 3  5   8   | 2 4 9 | 7 6  1  |
| 49 1   49  | 7 6 3 | 5 2  8  |
| 6  27  27  | 8 5 1 | 4 9  3  |
+------------+-------+---------+
| 5  67  467 | 9 1 2 | 8 3  47 |
| 47 9   1   | 6 3 8 | 2 47 5  |
| 28 28  3   | 5 7 4 | 9 1  6  |
+------------+-------+---------+
| 28 3   5   | 1 9 7 | 6 48 24 |
| 79 4   279 | 3 8 6 | 1 5  27 |
| 1  678 67  | 4 2 5 | 3 78 9  |
+------------+-------+---------+

Play this puzzle online at the Daily Sudoku site

Quote:
Coloring 7r5c1-r5c8=r4c9-r8c9=> -7r8c1
Back to top
View user's profile Send private message
keith



Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA

PostPosted: Fri Feb 19, 2016 6:32 am    Post subject: Reply with quote

Marty,

Yes, I saw a skyscraper on 7 in C19.

But also, an XYZ-wing that takes 7 out of R9C3, leading to a BUG+1.

Or, even cooler, the pseudo-cell 48 in the 67 UR that makes an XY-wing 4-78 which makes eliminations in C89.

Keith
Back to top
View user's profile Send private message
Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA

PostPosted: Fri Feb 19, 2016 8:05 am    Post subject: Reply with quote

keith wrote:
Marty,

Yes, I saw a skyscraper on 7 in C19.

But also, an XYZ-wing that takes 7 out of R9C3, leading to a BUG+1.

Or, even cooler, the pseudo-cell 48 in the 67 UR that makes an XY-Wing 4-78 which makes eliminations in C89.

Keith


I don't understand anything about the pseudo cell XY-Wing.

Another way to get rid of the 7 in r9c3 other than the XYZ-Wing is to play the UR as a Type 6, which it is.

And the W-Wing on 67 sets up the Bug+1.
Back to top
View user's profile Send private message
keith



Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA

PostPosted: Fri Feb 19, 2016 4:57 pm    Post subject: Reply with quote

Marty R. wrote:
keith wrote:
Marty,

Yes, I saw a skyscraper on 7 in C19.

But also, an XYZ-wing that takes 7 out of R9C3, leading to a BUG+1.

Or, even cooler, the pseudo-cell 48 in the 67 UR that makes an XY-Wing 4-78 which makes eliminations in C89.

Keith


I don't understand anything about the pseudo cell XY-Wing.

Another way to get rid of the 7 in r9c3 other than the XYZ-Wing is to play the UR as a Type 6, which it is.

And the W-Wing on 67 sets up the Bug+1.


Code:
+----------------+-------+-------------+
| 3    5     8   | 2 4 9 | 7   6    1  |
| 49   1     49  | 7 6 3 | 5   2    8  |
| 6    27    27  | 8 5 1 | 4   9    3  |
+----------------+-------+-------------+
| 5    67  (4)67 | 9 1 2 | 8   3  (47) |
| 47   9     1   | 6 3 8 | 2   4-7  5  |
| 28   28    3   | 5 7 4 | 9   1    6  |
+----------------+-------+-------------+
| 28   3     5   | 1 9 7 | 6   48   24 |
| 79   4     279 | 3 8 6 | 1   5    2-7|
| 1    67(8) 67  | 4 2 5 | 3 (78)   9  |
+----------------+-------+-------------+ 

Maybe you call it something different.

In the UR R4C3 is 4 and/or R9C2 is 8. This sets up pincers on 7 in R6C9 and R9C8.

Keith
Back to top
View user's profile Send private message
Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA

PostPosted: Fri Feb 19, 2016 7:43 pm    Post subject: Reply with quote

I don't know what to call it, but it provides the opening premise for a chain.

4r4c3=8r9c2-(8=7)r9c8-(7=2)r8c9-(2=4)r7c9=> -4r4c9.
Back to top
View user's profile Send private message
dongrave



Joined: 06 Mar 2014
Posts: 568

PostPosted: Sat Feb 20, 2016 2:35 am    Post subject: Reply with quote

Marty R. wrote:

Quote:
7r5c1-r5c8=r4c9-r8c9=> -7r8c1

Hi Marty, Don't the strong and weak links in your chain have to be just the opposite because if you end your chain with the weak link between r4c9 and r8c9, doesn't that imply that a strong link should exist between r8c9 and r8c1 - which is ruined by the 7 in r8c3? I'm probably just confused again - it seemed to me that it would have to be represented as 7r5c1=r5c8-r4c9=r8c9-r8c1; contradiction. This Eureka notation still confuses me sometimes. Thanks, Don.
Back to top
View user's profile Send private message
Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA

PostPosted: Sat Feb 20, 2016 5:18 am    Post subject: Reply with quote

That's not a standard chain that is usually notated Don. It's Simple Coloring, in which you need an even number of cells with the start and end cells having opposite "polarity." So the four cells I used are plus, minus, plus, minus and I tried to Eurekaize it.
Back to top
View user's profile Send private message
dongrave



Joined: 06 Mar 2014
Posts: 568

PostPosted: Sat Feb 20, 2016 1:41 pm    Post subject: Reply with quote

Oh, I see! My chain was so similar to yours but mine was a strict chain so you had me wondering there! (4-7)r5c1=r8c1-r8c9=r4c9=>r4c23<>7. Hey! Last time I posted a chain w/ pincers on both ends I think you told me that most would begin the chain as '7r5c1=...' instead of '(4-7)r5c1' so I guess that would be the case here too? I thought maybe the '(4-7)' would accentuate the fact that it's saying 'If r5c1 is not a 7, then r4c9 is 7.' but it's not really necessary (or even preferred), is it? Thanks, Don.
Back to top
View user's profile Send private message
Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA

PostPosted: Sat Feb 20, 2016 1:59 pm    Post subject: Reply with quote

Don, I could've written it differently and, Perhaps, more conventionally as:

(7=4)r5c1-(4=7)r5c8-r4c9=r8c9=> -7r8c1
Back to top
View user's profile Send private message
dongrave



Joined: 06 Mar 2014
Posts: 568

PostPosted: Sat Feb 20, 2016 2:12 pm    Post subject: Reply with quote

Of course! I like it (because even I can understand it).
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    dailysudoku.com Forum Index -> Other puzzles All times are GMT
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group