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 

Dec 11 VH

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



Joined: 16 May 2010
Posts: 33

PostPosted: Tue Dec 11, 2012 10:15 am    Post subject: Dec 11 VH Reply with quote

After basics
Code:

+------------+----------------------+---------------+
| 37  36  8  | 3579   1      3579   | 257 269  4    |
| 1   46  59 | 45789  4579   2      | 578 3    69   |
| 347 2   59 | 6      34579  345789 | 578 189  19   |
+------------+----------------------+---------------+
| 25  179 4  | 2579   25679  1579   | 3   267  8    |
| 25  17  3  | 24578  24567  14578  | 9   2467 256  |
| 8   79  6  | 234579 234579 34579  | 1   247  25   |
+------------+----------------------+---------------+
| 34  8   17 | 2479   2479   6      | 24  5    1239 |
| 6   5   2  | 1      349    349    | 48  89   7    |
| 9   34  17 | 2457   8      457    | 6   12   123  |
+------------+----------------------+---------------+


I need 2 steps to solve.
XYZ Wing 189 pivoted at r3c8; r1c8 <>9 followed by
XY Wing 23-4 pivoted at r9c9; r7c1<>4
Back to top
View user's profile Send private message
George Woods



Joined: 28 Mar 2006
Posts: 304
Location: Dorset UK

PostPosted: Tue Dec 11, 2012 11:23 am    Post subject: another almost xy Reply with quote

this is a 1 stepper after only3 numbers have been entered!
If r9c9 <>1 then xy 234 pivoted at r7c7 sets r9c2 =4 else if r9c9 =1 simple eliminations lead to r9c2 =4

so r9c2 = 4 and this solves it
Back to top
View user's profile Send private message
arkietech



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

PostPosted: Tue Dec 11, 2012 12:36 pm    Post subject: Reply with quote

The first step solves it.

Code:
 
 *-----------------------------------------------------------------------------*
 | 37      36      8       | 3579    1       3579    | 257     269     4       |
 | 1       46      59      | 45789   4579    2       | 578     3       69      |
 | 347     2       59      | 6       34579   345789  | 578     189     19      |
 |-------------------------+-------------------------+-------------------------|
 | 25      179     4       | 2579    25679   1579    | 3       267     8       |
 | 25      17      3       | 24578   24567   14578   | 9       2467    256     |
 | 8       79      6       | 234579  234579  34579   | 1       247     25      |
 |-------------------------+-------------------------+-------------------------|
 |a34      8       17      | 2479    2479    6       |b24      5       129-3   |
 | 6       5       2       | 1       349     349     | 48      89      7       |
 | 9       4-3     17      | 2457    8       457     | 6      c12     c123     |
 *-----------------------------------------------------------------------------*
(3=4)r7c1-(4=2)r7c7-(2=3)r9c89 => -3r7c9,r9c2; stte
Back to top
View user's profile Send private message
hughwill



Joined: 05 Apr 2010
Posts: 424
Location: Birmingham UK

PostPosted: Tue Dec 11, 2012 12:50 pm    Post subject: Dec 11 VH Reply with quote

Quote:
if r9c9 =1 simple eliminations lead to r9c2 =4


George- If r9c9=1 then surely r9c2 has the only remaining 3 on the row....or
have I as usual misunderstood?

Dan- Is there a name for your pseudo XY wing?



Hugh
Back to top
View user's profile Send private message
arkietech



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

PostPosted: Tue Dec 11, 2012 1:50 pm    Post subject: Re: Dec 11 VH Reply with quote

hughwill wrote:
Dan- Is there a name for your pseudo XY wing?


Yes it is an als xy-wing -- remove the 2 from column 89 of row 9 and it forces r9c8 =1 and r9c9=3.
Back to top
View user's profile Send private message
George Woods



Joined: 28 Mar 2006
Posts: 304
Location: Dorset UK

PostPosted: Tue Dec 11, 2012 2:22 pm    Post subject: Re: Dec 11 VH Reply with quote

hughwill wrote:
Quote:
if r9c9 =1 simple eliminations lead to r9c2 =4


George- If r9c9=1 then surely r9c2 has the only remaining 3 on the row....or
have I as usual misunderstood?

Dan- Is there a name for your pseudo XY wing?



Hugh

No not quite a misunderstanding but the reasoning below that denies the 1 smacks of "trial and error"

If r9 is 1 then as you say r9c2 is 3 BUT also it must be a 4 since solving 124 in Block 9 forces r9c2 to be 4 so this shows that it can't be 1 and the simple xy wing now says that r9c2 is 4 .......
Back to top
View user's profile Send private message
Marty R.



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

PostPosted: Tue Dec 11, 2012 3:17 pm    Post subject: Reply with quote

It's my personal preference to limit myself to the standard VH moves on these puzzle and I needed two of them: XYZ-Wing on 189 pivoted in r3c8 and the XY-Wing on 243 pivoted in r7c7. Interesting puzzle, as the large number of polyvalue cells required care as well.
Back to top
View user's profile Send private message
Marty R.



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

PostPosted: Tue Dec 11, 2012 4:05 pm    Post subject: Reply with quote

Quote:
If r9 is 1 then as you say r9c2 is 3 BUT also it must be a 4 since solving 124 in Block 9 forces r9c2 to be 4 so this shows that it can't be 1 and the simple xy wing now says that r9c2 is 4 .......


By the way, Ted uses this type of move and calls it an Almost XY-Wing, or AXY.
Back to top
View user's profile Send private message
keith



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

PostPosted: Tue Dec 11, 2012 6:37 pm    Post subject: Reply with quote

Marty R. wrote:
Quote:
If r9 is 1 then as you say r9c2 is 3 BUT also it must be a 4 since solving 124 in Block 9 forces r9c2 to be 4 so this shows that it can't be 1 and the simple xy wing now says that r9c2 is 4 .......


By the way, Ted uses this type of move and calls it an Almost XY-Wing, or AXY.

A while ago we played with this and called it a finned XY-wing, the idea being that an extra digit in an XY-wing is a fin.

I would prefer "almost" since the fish people have their definition of what a fin is.

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



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

PostPosted: Tue Dec 11, 2012 7:16 pm    Post subject: Reply with quote

keith wrote:

A while ago we played with this and called it a finned XY-wing, the idea being that an extra digit in an XY-wing is a fin.

I would prefer "almost" since the fish people have their definition of what a fin is.

Keith


I remember it well, the first example of what was called a "Finned" XY-Wing, which seems appropriate. However, Ted is the leading user and he uses "Almost", so that's how I now refer to it.
Back to top
View user's profile Send private message
keith



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

PostPosted: Tue Dec 11, 2012 8:46 pm    Post subject: Reply with quote

Marty R. wrote:
keith wrote:

A while ago we played with this and called it a finned XY-wing, the idea being that an extra digit in an XY-wing is a fin.

I would prefer "almost" since the fish people have their definition of what a fin is.

Keith


I remember it well, the first example of what was called a "Finned" XY-Wing, which seems appropriate. However, Ted is the leading user and he uses "Almost", so that's how I now refer to it.


Here is the original thread, which refers to others:

http://www.dailysudoku.com/sudoku/forums/viewtopic.php?p=12552

Very interesting reading!

No offense to current participants, but I miss Asellus and Nataraj!

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



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

PostPosted: Wed Dec 12, 2012 1:40 am    Post subject: Reply with quote

Quote:
Very interesting reading!

No offense to current participants, but I miss Asellus and Nataraj!


Interesting indeed.

I miss those two guys as well. I've been active on various forums ever since I got my first computer 13 years ago and if there's one constant, it's that people come and go.

When I first joined here almost seven years ago the cast of characters was different; you might be the only one still left. There was David Bryant of DIC fame who was the most prolific poster until he dropped out and I eventually took over that unfortunate "honor."

There was Tracy, Ravel, Steve, and dozens of others who don't come to mind. Sam even posted in those days!

Nothing stays the same.
Back to top
View user's profile Send private message
hughwill



Joined: 05 Apr 2010
Posts: 424
Location: Birmingham UK

PostPosted: Wed Dec 12, 2012 4:44 pm    Post subject: Dec 11 VH Reply with quote

Quote:
I miss those two guys as well. I've been active on various forums ever since I got my first computer 13 years ago and if there's one constant, it's that people come and go.


If it's any solace, Nataraj posted on 'other puzzles' today (to celebrate 12.12.12). However Assellus stopped suddenly(?) just over a year ago...
Tout ca change, tout c'est la meme chose.
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