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 

DB Saturday Puzzle: September 1, 2007

 
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: Sat Sep 01, 2007 3:16 pm    Post subject: DB Saturday Puzzle: September 1, 2007 Reply with quote

Code:
Puzzle: DB090107 ******
+-------+-------+-------+
| 2 . . | . . . | . . . |
| 4 . . | 8 . 6 | . 3 . |
| 8 9 . | . 3 1 | . . . |
+-------+-------+-------+
| . . 4 | . 1 9 | 2 . 8 |
| . . . | . . . | . . . |
| 5 . 9 | 7 8 . | 1 . . |
+-------+-------+-------+
| . . . | 1 5 . | . 2 7 |
| . 7 . | 3 . 8 | . . 6 |
| . . . | . . . | . . 9 |
+-------+-------+-------+


An easy W-wing is one way ...

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



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

PostPosted: Sat Sep 01, 2007 3:57 pm    Post subject: Sept 1 DB Reply with quote

Also an xy-wing eliminates 2 from R2C5, and opens the puzzle.

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



Joined: 30 Apr 2007
Posts: 119
Location: Rotterdam, NL

PostPosted: Sat Sep 01, 2007 4:28 pm    Post subject: Reply with quote

I saw the other XY wing, eliminating 2 also from R5C5 (pivot at R1C6):

Code:

+-----------+-----------+------------+
| 2  156 3  | 9  4   57 | 67  8  15  |
| 4  15  17 | 8  27  6  | 9   3  125 |
| 8  9   67 | 25 3   1  | 467 47 25  |
+-----------+-----------+------------+
| 67 3   4  | 56 1   9  | 2   57 8   |
| 67 18  18 | 4  26  25 | 57  9  3   |
| 5  2   9  | 7  8   3  | 1   6  4   |
+-----------+-----------+------------+
| 9  68  68 | 1  5   4  | 3   2  7   |
| 1  7   2  | 3  9   8  | 45  45 6   |
| 3  4   5  | 26 267 27 | 8   1  9   |
+-----------+-----------+------------+

Play this puzzle online at the Daily Sudoku site

Peter
Back to top
View user's profile Send private message Visit poster's website
Marty R.



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

PostPosted: Sat Sep 01, 2007 4:42 pm    Post subject: Reply with quote

I missed the W, but the one XY did it.
Back to top
View user's profile Send private message
keith



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

PostPosted: Sat Sep 01, 2007 5:32 pm    Post subject: Reply with quote

Marty R. wrote:
I missed the W ...

Look at <26> in C45, connected by strong link on <2> in B2. Takes out <6> in R9C5.

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



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

PostPosted: Sat Sep 01, 2007 11:09 pm    Post subject: Reply with quote

I missed the xy- wing, but found a 4-cell xy-chain

Starting with <6> in R4C4 => R9C4=2 => R9C6=7 => R1C6=5, resulting in two <5> pincer cells in R4C4 and R1C6, eliminating both <5>'s in R5C6 and R3C4(both can see the <5> pincer cells)

[56][62][27][75]
Back to top
View user's profile Send private message Send e-mail
Asellus



Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA

PostPosted: Sat Sep 01, 2007 11:39 pm    Post subject: Reply with quote

As an interesting alternative to the single XY Wing solution...

Note the {15} UR in R12C29. There is a <5> strong link in C2 and a <1> strong link in C9. Thus, <1> is removed from R1C2 and 5 is removed from R2C9.
Back to top
View user's profile Send private message Visit poster's website
Johan



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

PostPosted: Sun Sep 02, 2007 12:39 am    Post subject: Reply with quote

Asellus,

I followed a diffirent solving path for the [15] UR you mentioned.

For avoiding the deadly [15] pattern in R12C29.
R1C2 must be <6> or R2C9 must be <2>.

Presume that R2C9=2 => R2C5=7 => R1C6=5 => R1C9=1

=> R1C2=6, which means that <6> can only reside in R1C2, logical thinking(or did I make a lucky guess)?

Because <6> acts like a pincer cell, starting with <2> in R2C9 ends up with <6> in R1C2, which pins the <6> in R1C2.
Back to top
View user's profile Send private message Send e-mail
Asellus



Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA

PostPosted: Sun Sep 02, 2007 7:45 pm    Post subject: Reply with quote

Johan wrote:
logical thinking(or did I make a lucky guess)?

Your logic is fine: either candidate for avoiding the DP forces the other.
Back to top
View user's profile Send private message Visit poster's website
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