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 

May 30 VH

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



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

PostPosted: Thu May 29, 2008 10:37 pm    Post subject: May 30 VH Reply with quote

Did anyone else solve this by 2 W wings in direct sequence?

I recognize that my solution may well be a transposition of some other technique such as colouring 7s.
Back to top
View user's profile Send private message
Marty R.



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

PostPosted: Fri May 30, 2008 4:55 am    Post subject: Reply with quote

I did it with multi-coloring on 7 followed by a W-Wing, which is not to say that there wasn't a W-Wing available at first that I missed.
Back to top
View user's profile Send private message
nataraj



Joined: 03 Aug 2007
Posts: 1048
Location: near Vienna, Austria

PostPosted: Fri May 30, 2008 5:37 am    Post subject: Reply with quote

Here's what I did:
After basics...
Code:


+--------------------------+--------------------------+--------------------------+
| 49      2       3        | 8       49      57       | 57      1       6        |
| 47      6       5        | 1       3       2        | 8       9       47       |
| 1       789     48       | 457     4569    567      | 2       457     3        |
+--------------------------+--------------------------+--------------------------+
| 259     589     6        | 359     1       4        | 39      578     257      |
| 3       589     7        | 59      2       58       | 4       6       1        |
| 2459    1       48       | 6       7       358      | 39      58      25       |
+--------------------------+--------------------------+--------------------------+
| 8       57      2        | 3457    456     3567     | 1       457     9        |
| 57      4       9        | 2       58      1        | 6       3       578      |
| 6       3       1        | 457     458     9        | 57      2       4578     |
+--------------------------+--------------------------+--------------------------+

play online

X-wing on 7 (rows 2 and 8, removes 7 from r49c9). This solves many cells.

Then here:
Code:

+--------------------------+--------------------------+--------------------------+
| 49      2       3        | 8       49      57       | 57      1       6        |
| 47      6       5        | 1       3       2        | 8       9       47       |
| 1       79      8        | 457     4569    567      | 2       45      3        |
+--------------------------+--------------------------+--------------------------+
| 259     8       6        | 359     1       4        | 39      7       25       |
| 3       59      7        | 59      2       8        | 4       6       1        |
| 259     1       4        | 6       7       35       | 39      8       25       |
+--------------------------+--------------------------+--------------------------+
| 8       57      2        | 3457    456     3567     | 1       45      9        |
| 57      4       9        | 2       58      1        | 6       3       78       |
| 6       3       1        | 457     458     9        | 57      2       48       |
+--------------------------+--------------------------+--------------------------+

play online

...UR 25 r46c19 (in order to avoid the deadly pattern, r46c1 must contain 9) solves r1c1=4 and r5c2=9.
Back to top
View user's profile Send private message Send e-mail Visit poster's website
George Woods



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

PostPosted: Fri May 30, 2008 6:26 am    Post subject: The Double w wing solution Reply with quote

Taking the first grid provided by Nataraj :-

57s in boxes 7,9 operating on row 8 deny a 5 to r7c8 which becomes 47
47s in boxes 3,9 operating on col 7 deny 4 to r3c8 so r2c9 is 4 ..... and
it falls out thereafter!


Last edited by George Woods on Fri May 30, 2008 4:46 pm; edited 1 time in total
Back to top
View user's profile Send private message
Johan



Joined: 25 Jun 2007
Posts: 206
Location: Bornem Belgium

PostPosted: Fri May 30, 2008 7:30 am    Post subject: Reply with quote

The 25 UR* in R46C19 pins <7> in R2C1, all three solutions for avoiding the possible 25 DP ends up with <7> in R2C1, which succumbs the puzzle.

#1 R46C1=9 => R1C1=4 => R2C1=7

#2 R6C1=4 => R2C1=7

#3 R4C9=7 => R2C9=4 => R2C1=7
Code:
+-------------------------+-------------------------+-------------------------+
| 49        2         3   | 8         49       57   | 57        1       6     |
| 4=7       6         5   | 1         3        2    | 8         9       47    |
| 1         789       48  | 457       4569     567  | 2         457     3     |
+-------------------------+-------------------------+-------------------------+
|*25+9      589       6   | 359       1        4    | 39        578    *25+7  |
| 3         589       7   | 59        2        58   | 4         6       1     |
|*25+49     1         48  | 6         7        358  | 39        58     *25    |
+-------------------------+-------------------------+-------------------------+
| 8         57        2   | 3457      456      3567 | 1         457     9     |
| 57        4         9   | 2         58       1    | 6         3       578   |
| 6         3         1   | 457       458      9    | 57        2       4578  |
+-------------------------+-------------------------+-------------------------+
Back to top
View user's profile Send private message Send e-mail
tlanglet



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

PostPosted: Fri May 30, 2008 12:44 pm    Post subject: Reply with quote

My route was a little longer, and more basic but interesting. After the initial x-wing on <7> to eliminate r49c9, I noticed two finned x-wings on <7> in r37c24 and r37c26. Then I realized that these two "interlocked" finned x-wings were part of a "jellyfish" in r1379c2467 that deleted r9c9 (as did the initial x-wing). The two finned x-wings destroyed each other but I removed the <7> for both: r7c6 and r3c4.

After significant clean-up, I still had to remove the <4> at r7c5 based on coloring to complete the puzzle.

This was the first "jellyfish" that I have actually found!

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



Joined: 04 May 2007
Posts: 769
Location: ontario, canada

PostPosted: Fri May 30, 2008 1:16 pm    Post subject: Reply with quote

That UR Johan mentioned is a TYPE 4. Since there are only two 2's in C1 we can remove the 5's from C1 Box4. I know this because I am an expert in Type 4 URs (since last Tuesday).

Though it seems I still had to use an x-wing in R28 to remove a <7> and set up the UR.
Back to top
View user's profile Send private message
Earl



Joined: 30 May 2007
Posts: 677
Location: Victoria, KS

PostPosted: Fri May 30, 2008 2:17 pm    Post subject: May 30 VH Reply with quote

After the x-wing of 7's, there is an xy-wing (578) in boxes 8&9 which solves the puzzle. There is also an xyz-wing (457) in boxes 2&3, but it does not finish the puzzle.

Earl
Back to top
View user's profile Send private message Send e-mail
tlanglet



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

PostPosted: Fri May 30, 2008 3:08 pm    Post subject: Reply with quote

cgordon wrote:
That UR Johan mentioned is a TYPE 4. Since there are only two 2's in C1 we can remove the 5's from C1 Box4. I know this because I am an expert in Type 4 URs (since last Tuesday).

Though it seems I still had to use an x-wing in R28 to remove a <7> and set up the UR.


In this case, the <5>s inr46c1 are removed by the <7> in r2c1 which makes r8c1=5.

However I understood that a Type 4 UR required the other two cells to be bivalues. In this case, cell r4c9 contains a extra digit so that in fact the solution could have a <5> in either r46c1.

Did I overlook something? Question

Ted

Edit: Yes, I did overlook something! The comment by Craig was obviously appropriate after the x-wing removed the <7> inr4c9. (I don't like Friday either.)


Last edited by tlanglet on Fri May 30, 2008 8:12 pm; edited 1 time in total
Back to top
View user's profile Send private message
stevieboy



Joined: 25 Jan 2008
Posts: 31
Location: Michigan

PostPosted: Fri May 30, 2008 4:00 pm    Post subject: Reply with quote

nataraj wrote:

...UR 25 r46c19 (in order to avoid the deadly pattern, r46c1 must contain 9) solves r1c1=4 and r5c2=9.


That's what did it for me, too!
Back to top
View user's profile Send private message
Florida Bob



Joined: 25 Jul 2007
Posts: 12

PostPosted: Fri May 30, 2008 4:01 pm    Post subject: First x- wing Reply with quote

It must be Friday however, I can't see the x-wing that eliminates the 7's in rows 4 & 9 col. 9. Could someone be more specific.
Back to top
View user's profile Send private message
stevieboy



Joined: 25 Jan 2008
Posts: 31
Location: Michigan

PostPosted: Fri May 30, 2008 4:34 pm    Post subject: Reply with quote

No problem, Florida Bob,

The '7's in Rows 2 and 8, as well as along Column 1 are strong pairs (one or the other cell along those paths HAS to be a '7').

Therefore, in Column 9, the 7 HAS to be in either, in Row 2 or Row 8 - ONE OR THE OTHER.

So, any '7' along the rectangular path mentioned above, CAN NOT contain a '7'.

Take it easy!
Back to top
View user's profile Send private message
andras



Joined: 31 Oct 2007
Posts: 56
Location: Mid Wales

PostPosted: Fri May 30, 2008 5:58 pm    Post subject: Reply with quote

It certainly took a little time, but was fun in the end.

Perhaps we need a new category beyone 'VH' for these puzzzles that need multiple advanced techniques. Can I suggest Death By Sudoku? Smile

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



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Fri May 30, 2008 7:39 pm    Post subject: Re: First x- wing Reply with quote

Florida Bob wrote:
It must be Friday however, I can't see the x-wing that eliminates the 7's in rows 4 & 9 col. 9. Could someone be more specific.




the above image shows the 7's in rows 2 and 8. sudoku tells us that a 7 must occupy one of those rows. so regardless which column we put a 7 in, a 7 must go in the other one, ( either col 1 or 9 ) therefore any other 7's in col 1 or 9 can be eliminated.

george woods,

I like the double w-wing approach... I find these easier to find than xy-wings.
Back to top
View user's profile Send private message
storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Fri May 30, 2008 7:48 pm    Post subject: Reply with quote

andras wrote:
It certainly took a little time, but was fun in the end.

Perhaps we need a new category beyone 'VH' for these puzzzles that need multiple advanced techniques. Can I suggest Death By Sudoku? Smile

John


do you venture into the "other puzzles" category?
Back to top
View user's profile Send private message
andras



Joined: 31 Oct 2007
Posts: 56
Location: Mid Wales

PostPosted: Fri May 30, 2008 8:41 pm    Post subject: Reply with quote

storm_norm wrote:
andras wrote:
It certainly took a little time, but was fun in the end.

Perhaps we need a new category beyone 'VH' for these puzzzles that need multiple advanced techniques. Can I suggest Death By Sudoku? Smile

John


do you venture into the "other puzzles" category?


I don't dare - I have a life to lead as well as doing Sudoku and crosswords! Wink

John
Back to top
View user's profile Send private message
nataraj



Joined: 03 Aug 2007
Posts: 1048
Location: near Vienna, Austria

PostPosted: Fri May 30, 2008 10:03 pm    Post subject: Reply with quote

andras wrote:


I don't dare - I have a life to lead as well as doing Sudoku and crosswords! Wink


But that is only the OTHER life !

Twisted Evil Laughing
Back to top
View user's profile Send private message Send e-mail Visit poster's website
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