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 

Jan 4 VH

 
Post new topic   Reply to topic    dailysudoku.com Forum Index -> Daily Sudoku puzzles
View previous topic :: View next topic  
Author Message
Clement



Joined: 24 Apr 2006
Posts: 1111
Location: Dar es Salaam Tanzania

PostPosted: Sun Jan 03, 2010 10:29 pm    Post subject: Jan 4 VH Reply with quote

XY-Wing - <34>-<46>-<36> eliminating 3 in r6c3 solves the puzzle.
There is also a UR-Type 1 <28> in r23c27 which solves it.
Back to top
View user's profile Send private message AIM Address
tlanglet



Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills

PostPosted: Mon Jan 04, 2010 12:38 am    Post subject: Reply with quote

A BUG+2 condition or a xy-wing13-4 with both pincer being transported are also one steppers.

Ted
Back to top
View user's profile Send private message
storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Wed Jan 06, 2010 1:52 am    Post subject: Reply with quote

trying something different...
sudocue offers a optimizing function and a canonacalizing functiong...
when I use those features on this puzzle the result looks like the puzzle below.
I guess i would have ask the moderators if its against the site's policy to rearrange the puzzle and make it a tad more difficult???
Marty?
Keith?

if not then an optimized version of the VH might be worth exploring in these threads, especially if they require just a tad more than the normal x,xy,xyz-wings to solve.
A.K.A. VH+ type puzzle, but nothing extreme.

just an idea... here is an example from the VH in this thread.

000000001000002030412050600000000007005006040023070800000003000106020300907600000

Code:

+-------+-------+-------+
| . . . | . . . | . . 1 |
| . . . | . . 2 | . 3 . |
| 4 1 2 | . 5 . | 6 . . |
+-------+-------+-------+
| . . . | . . . | . . 7 |
| . . 5 | . . 6 | . 4 . |
| . 2 3 | . 7 . | 8 . . |
+-------+-------+-------+
| . . . | . . 3 | . . . |
| 1 . 6 | . 2 . | 3 . . |
| 9 . 7 | 6 . . | . . . |
+-------+-------+-------+

Play online

this puzzle does not solve with the normal xy-wing even tho its based entirely on its VH cousin.

comments?
opinions?
rants?
raves?
Back to top
View user's profile Send private message
arkietech



Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA

PostPosted: Wed Jan 06, 2010 2:42 am    Post subject: Reply with quote

I just needed a turbot 1. Did I miss something?
Back to top
View user's profile Send private message
storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Wed Jan 06, 2010 2:53 am    Post subject: Reply with quote

no
Back to top
View user's profile Send private message
Marty R.



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

PostPosted: Wed Jan 06, 2010 4:53 am    Post subject: Reply with quote

Quote:
I guess i would have ask the moderators if its against the site's policy to rearrange the puzzle and make it a tad more difficult???
Marty?
Keith?

Can't speak for Keith, but I was made a moderator without guidelines or policies. But go ahead, that seems a legitimate topic.
Back to top
View user's profile Send private message
Wendy W



Joined: 04 Feb 2008
Posts: 144

PostPosted: Sun Jan 10, 2010 12:29 am    Post subject: Reply with quote

Norm, I got this far but I'm not seeing the turbot...can you help? Thanks.
+---------+-----------------+---------------+
| 3 67 89 | 4789 4689 4789 | 5 2 1 |
| 5 67 89 | 1789 1689 2 | 479 3 489 |
| 4 1 2 | 3 5 789 | 6 789 89 |
+---------+-----------------+---------------+
| 8 4 1 | 259 3 59 | 29 6 7 |
| 7 9 5 | 128 18 6 | 12 4 3 |
| 6 2 3 | 149 7 149 | 8 159 59 |
+---------+-----------------+---------------+
| 2 58 4 | 15789 189 3 | 179 1789 6 |
| 1 58 6 | 45789 2 4789 | 3 789 4589 |
| 9 3 7 | 6 148 1458 | 14 158 2 |
+---------+-----------------+---------------+
Back to top
View user's profile Send private message
Marty R.



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

PostPosted: Sun Jan 10, 2010 12:35 am    Post subject: Reply with quote

Here's the grid from the above post:

Code:
+---------+-----------------+----------------+
| 3 67 89 | 4789  4689 4789  | 5   2    1    |
| 5 67 89 | 1789  1689 2     | 479 3    489  |
| 4 1  2  | 3     5    789   | 6   789  89   |
+---------+-----------------+----------------+
| 8 4  1  | 259   3    59    | 29  6    7    |
| 7 9  5  | 128   18   6     | 12  4    3    |
| 6 2  3  | 149   7    149   | 8   159  59   |
+---------+-----------------+----------------+
| 2 58 4  | 15789 189  3     | 179 1789 6    |
| 1 58 6  | 45789 2    4789  | 3   789  4589 |
| 9 3  7  | 6     148  1458  | 14  158  2    |
+---------+-----------------+----------------+
Back to top
View user's profile Send private message
keith



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

PostPosted: Sun Jan 10, 2010 1:20 am    Post subject: Reply with quote

Marty R. wrote:
Here's the grid from the above post:

Code:
+---------+-----------------+----------------+
| 3 67 89 | 4789  4689 4789  | 5   2    1    |
| 5 67 89 | 1789  1689 2     | 479 3    489  |
| 4 1  2  | 3     5    789   | 6   789  89   |
+---------+-----------------+----------------+
| 8 4  1  | 259   3    59    | 29  6    7    |
| 7 9  5  | 128   18   6     | 12# 4    3    |
| 6 2  3  | 149   7    149@  | 8   159@ 59   |
+---------+-----------------+----------------+
| 2 58 4  | 15789 189  3     | 179 1789 6    |
| 1 58 6  | 45789 2    4789  | 3   789  4589 |
| 9 3  7  | 6     148  1458# |-14  158  2    |
+---------+-----------------+----------------+

One of @ in R6 is not true: On of # in C6, B6 is true: R9C7 is not 1.

Keith
Back to top
View user's profile Send private message
Wendy W



Joined: 04 Feb 2008
Posts: 144

PostPosted: Sun Jan 10, 2010 2:04 am    Post subject: Reply with quote

Thanks, guys! I'm still having trouble grasping the whole turbot concept. Can you talk me through how you would go about spotting this?
Back to top
View user's profile Send private message
keith



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

PostPosted: Sun Jan 10, 2010 3:46 am    Post subject: Reply with quote

Wendy W wrote:
Thanks, guys! I'm still having trouble grasping the whole turbot concept. Can you talk me through how you would go about spotting this?

Some may not agree, but:

Turbot fish is a generic name that includes skyscrapers, kites, and most empty rectangles (hinges). These are all based on the simplest form of multi-coloring, two strong links.

A great introduction is Havard's paper on strong links:

http://www.sudoku.com/boards/viewtopic.php?t=3326

Then, you could look up Turbot Fish at Sudopedia and other sites.

How do you spot them? It's in the eye of the beholder.

As a start, how do you spot an X-wing? I look for a strong link, then I look for another strong link that lines up on both ends.

How do you find a Turbot? Look for a strong link, then look for another strong link that lines up on one end. Where they line up, one must be false; at the other ends (pincers), one must be true.

The current puzzle is a great example, and probably is the hardest variant to spot.

I wrote this a couple of weeks ago:

http://www.dailysudoku.com/sudoku/forums/viewtopic.php?t=4120

It did not get much reaction, but I have found it to be a great help when solving with pencil & paper.

Look at the nine boxes in a Sudoku grid. Eliminate all boxes where the candidate is solved. Eliminate all boxes where the candidate exists only in one row or one column. A Turbot elimination is only possible if the remaining boxes are on a rectangle. If an elimination exists, the links, and the elimination, are in that rectangle.

Code:
+---------+-----------------+----------------+
| 3 67 89 | 4789  4689 4789  | 5   2    1    |
| 5 67 89 | 1789  1689 2     | 479 3    489  |
| 4 1  2  | 3     5    789   | 6   789  89   |
+---------+-----------------+----------------+
| 8 4  1  | 259   3    59    | 29  6    7    |
| 7 9  5  | 128   18   6     | 12  4    3    |
| 6 2  3  | 149   7    149   | 8   159  59   |
+---------+-----------------+----------------+
| 2 58 4  | 15789 189  3     | 179 1789 6    |
| 1 58 6  | 45789 2    4789  | 3   789  4589 |
| 9 3  7  | 6     148  1458  | 14  158  2    |
+---------+-----------------+----------------+

Let's look at where 1 is solved (/)

Code:
+-+-+-+
|/|.|/|
+-+-+-+
|/|.|.|
+-+-+-+
|/|.|.|
+-+-+-+

Furthermore in B2 the candidates for 1 are only in R2. So, we have:
Code:
+-+-+-+
|/|/|/|
+-+-+-+
|/|.|.|
+-+-+-+
|/|.|.|
+-+-+-+

If there is a Turbot elimination on 1, the start and end points of the strong links, and the elimination, must lie in B5689.

Using this logic, you can quickly see that Turbot eliminations in this puzzle are not possible for 3 (solved), or for 2,4,5,6. You only need to look at 1, 7, 8, 9.

Keith
Back to top
View user's profile Send private message
daj95376



Joined: 23 Aug 2008
Posts: 3854

PostPosted: Sun Jan 10, 2010 4:58 am    Post subject: Reply with quote

Wendy W wrote:
Thanks, guys! I'm still having trouble grasping the whole turbot concept. Can you talk me through how you would go about spotting this?

Turbot fish are really fun once you understand them. I think multiple colors provides a nice (visual) understanding. Here's the candidate grid for <1>.

Code:
 Classic Turbot Fish
 ----------------------------------------------
 [c6] colored Blue/Green
 [b6] colored Pink/Amber
 Since Blue sees Amber in [r6]
 r9c7<>1 follows because it sees Green and Pink
 +-----------------------------------+
 |  .  .  .  |  .  .  .  |  .  .  1  |
 |  .  .  .  |  1  1  .  |  .  .  .  |
 |  .  1  .  |  .  .  .  |  .  .  .  |
 |-----------+-----------+-----------|
 |  .  .  1  |  .  .  .  |  .  .  .  |
 |  .  .  .  |  1  1  .  |  1P .  .  |
 |  .  .  .  |  1  .  1B |  .  1A .  |
 |-----------+-----------+-----------|
 |  .  .  .  |  1  1  .  |  1  1  .  |
 |  1  .  .  |  .  .  .  |  .  .  .  |
 |  .  .  .  |  .  1  1G | -1  1  .  |
 +-----------------------------------+

Code:
 Grouped 2-String Kite
 ----------------------------------------------
 [c6] colored Blue/Green
 [r5] colored Pink/Amber
 Since Blue sees (both) Amber in [b5]
 r9c7<>1 follows because it sees Green and Pink
 +-----------------------------------+
 |  .  .  .  |  .  .  .  |  .  .  1  |
 |  .  .  .  |  1  1  .  |  .  .  .  |
 |  .  1  .  |  .  .  .  |  .  .  .  |
 |-----------+-----------+-----------|
 |  .  .  1  |  .  .  .  |  .  .  .  |
 |  .  .  .  |  1A 1A .  |  1P .  .  |
 |  .  .  .  |  1  .  1B |  .  1  .  |
 |-----------+-----------+-----------|
 |  .  .  .  |  1  1  .  |  1  1  .  |
 |  1  .  .  |  .  .  .  |  .  .  .  |
 |  .  .  .  |  .  1  1G | -1  1  .  |
 +-----------------------------------+

This is a bit off the beaten path for turbot fish, but it works.

Code:
 finned X-Wing
 -----------------------------------------------------
 [c6] colored Blue/Green
 [c8] colored Pink/Amber
 Since Blue sees Amber in [r6]
 r9c7<>1 follows because it sees Green and (both) Pink
 +-----------------------------------+
 |  .  .  .  |  .  .  .  |  .  .  1  |
 |  .  .  .  |  1  1  .  |  .  .  .  |
 |  .  1  .  |  .  .  .  |  .  .  .  |
 |-----------+-----------+-----------|
 |  .  .  1  |  .  .  .  |  .  .  .  |
 |  .  .  .  |  1  1  .  |  1  .  .  |
 |  .  .  .  |  1  .  1B |  .  1A .  |
 |-----------+-----------+-----------|
 |  .  .  .  |  1  1  .  |  1  1P .  |
 |  1  .  .  |  .  .  .  |  .  .  .  |
 |  .  .  .  |  .  1  1G | -1  1P .  |
 +-----------------------------------+

Unfortunately, this grid doesn't contain an example for Skyscraper or Empty Rectangle. However, it can easily be altered to demonstrate a Skyscraper ... by removing <1> in r9c8.

Code:
 Skyscraper -or- (2x) Sashimi X-Wing
 ----------------------------------------------------
 [c6] colored Blue/Green
 [c8] colored Pink/Amber
 Since Blue sees Amber in [r6]
 r7c45,r9c7<>1 follow because they see Green and Pink
 +-----------------------------------+
 |  .  .  .  |  .  .  .  |  .  .  1  |
 |  .  .  .  |  1  1  .  |  .  .  .  |
 |  .  1  .  |  .  .  .  |  .  .  .  |
 |-----------+-----------+-----------|
 |  .  .  1  |  .  .  .  |  .  .  .  |
 |  .  .  .  |  1  1  .  |  1  .  .  |
 |  .  .  .  |  1  .  1B |  .  1A .  |
 |-----------+-----------+-----------|
 |  .  .  .  | -1 -1  .  |  1  1P .  |
 |  1  .  .  |  .  .  .  |  .  .  .  |
 |  .  .  .  |  .  1  1G | -1  .  .  |
 +-----------------------------------+
Back to top
View user's profile Send private message
Wendy W



Joined: 04 Feb 2008
Posts: 144

PostPosted: Sun Jan 10, 2010 4:35 pm    Post subject: Reply with quote

Thanks so much for your explanations. With the Eagles' season finished (American football), I will have time this afternoon to sit down and try to digest all this fishiness. Somehow I don't remember having this much trouble when I made the jump to VH puzzles!
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    dailysudoku.com Forum Index -> Daily Sudoku 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