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 

Need Help

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



Joined: 30 May 2007
Posts: 546
Location: St Louis MO

PostPosted: Tue Jul 03, 2007 3:15 am    Post subject: Need Help Reply with quote

I could use help on this one.

Thanks

Earl

Code:

+---------+-----------+------------+
| 9 7  18 | 18 3   2  | 5    6  4  |
| 6 18 3  | 4  159 15 | 28   29 7  |
| 4 5  2  | 89 7   6  | 38   1  39 |
+---------+-----------+------------+
| 2 16 9  | 7  145 3  | 46   8  56 |
| 7 68 18 | 19 245 45 | 2346 35 39 |
| 3 4  5  | 6  29  8  | 7    29 1  |
+---------+-----------+------------+
| 5 9  47 | 2  146 14 | 36   37 8  |
| 8 2  47 | 3  46  9  | 1    57 56 |
| 1 3  6  | 5  8   7  | 9    4  2  |
+---------+-----------+------------+

Play this puzzle online at the Daily Sudoku site
Back to top
View user's profile Send private message
jLo



Joined: 30 Apr 2007
Posts: 55

PostPosted: Tue Jul 03, 2007 5:10 am    Post subject: Reply with quote

After a W-wing with the 46's
a W-wing with the resulting 15's
a couple of X-wings on 1s
an X-wing on 9s

You end up here

Code:

+---------+---------+-----------+
|      18 | 18      |           |
|   18    |    19   | 28  29    |
|         | 89      | 38     39 |
+---------+---------+-----------+
|   16    |    15   |        56 |
|   68 18 | 19 25   | 236 35 39 |
|         |    29   |     29    |
+---------+---------+-----------+
|      47 |    46   | 36  37    |
|      47 |    46   |     57 56 |
|         |         |           |
+---------+---------+-----------+



From here I started coloring with R1C3 and ended up solving R5c7 which, pretty much
finished it off.
Back to top
View user's profile Send private message Yahoo Messenger
Earl



Joined: 30 May 2007
Posts: 546
Location: St Louis MO

PostPosted: Tue Jul 03, 2007 1:30 pm    Post subject: need help Reply with quote

jLo,

Thanks,

Is the grid you posted a BUG yielding a 3 in R5C7?

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



Joined: 30 Apr 2007
Posts: 55

PostPosted: Tue Jul 03, 2007 3:03 pm    Post subject: Reply with quote

Quote:

Is the grid you posted a BUG yielding a 3 in R5C7?


I hadn't noticed that, but yes it is.
Back to top
View user's profile Send private message Yahoo Messenger
Asellus



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

PostPosted: Tue Jul 03, 2007 6:38 pm    Post subject: Reply with quote

jLo's first W-Wing is also an XY-Chain.

There is another XY-Chain with pincers at R5C2 and R4C9 that eliminates <6> from R5C7.

These two XY-Chains solve the puzzle.

Nice to see the BUG+1!
Back to top
View user's profile Send private message Visit poster's website
Earl



Joined: 30 May 2007
Posts: 546
Location: St Louis MO

PostPosted: Tue Jul 03, 2007 8:03 pm    Post subject: Need Help Reply with quote

Asselius,

What is the difference between an "xy-chain" and an xy-wing"

Please explain slowly. I am a novice.

Thanks,

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



Joined: 03 May 2007
Posts: 695

PostPosted: Tue Jul 03, 2007 8:23 pm    Post subject: Reply with quote

XY Wing

http://www.sudoku9981.com/sudoku-solving/XY-Wing.asp

XY Wing

http://www.sudoku9981.com/sudoku-solving/XY-Chain.asp

An XY Wing is actually the shortest form of x-Y chain.
Back to top
View user's profile Send private message
jLo



Joined: 30 Apr 2007
Posts: 55

PostPosted: Wed Jul 04, 2007 5:26 am    Post subject: Reply with quote

Quote:

jLo's first W-Wing is also an XY-Chain.

There is another XY-Chain with pincers at R5C2 and R4C9 that eliminates <6> from R5C7.



I don't see either of these chains. Can you give me the long version?
Back to top
View user's profile Send private message Yahoo Messenger
TKiel



Joined: 22 Feb 2006
Posts: 292
Location: Kalamazoo, MI

PostPosted: Wed Jul 04, 2007 11:50 am    Post subject: Reply with quote

jLo wrote:
I don't see either of these chains. Can you give me the long version?


Not sure if this is the exact chain that Asellus used:

Code:
 
 *-----------------------------------------------------------*
 | 9     7     18c   | 18d   3     2     | 5     6     4     |
 | 6     18b   3     | 4     159   15    | 28    29    7     |
 | 4     5     2     | 89    7     6     | 38    1     39    |
 |-------------------+-------------------+-------------------|
 | 2     16    9     | 7     145   3     | 46    8     56j   |
 | 7     68a   18    | 19e   245   45    | 2346  35i   39h   |
 | 3     4     5     | 6     29f   8     | 7     29g   1     |
 |-------------------+-------------------+-------------------|
 | 5     9     47    | 2     146   14    | 36    37    8     |
 | 8     2     47    | 3     46    9     | 1     57    56    |
 | 1     3     6     | 5     8     7     | 9     4     2     |
 *-----------------------------------------------------------*


R5c2 shares <8> with r2c2, which leaves the <6> dangling. Now use the leftover digit in r2c2 <1> to link with another cell, in this case r1c3. The leftover digit there <8> links with r1c4. The chain is constructed in this manner, always alternating links, until another cell that has a <6> dangling is reached. When the two cells on the end of the chain have the same dangling digit and can both see a third cell that contains that digit, that digit can be eliminated from the third cell. In this case, the <6> in r5c7 and r4c2 can be eliminated.
Back to top
View user's profile Send private message
jLo



Joined: 30 Apr 2007
Posts: 55

PostPosted: Wed Jul 04, 2007 1:21 pm    Post subject: Reply with quote

Quote:

Not sure if this is the exact chain that Asellus used:


OK, I see that one, but what about one that
links the 46 at R8C5 with the 46 at R4C7? That's
how I interpreted the post that said the W-wing
was also an XY-chain. Since the W-wing eliminates
a 4 at R4C5, the end's of the XY-chain would have
to be a 4 to do the same elimination. The partner
value of the 4 at R4C7 is a 6 which appears three
times in each row, column, and block that R4C7
is part of, which makes in un-linkable from my view.
Back to top
View user's profile Send private message Yahoo Messenger
ravel



Joined: 21 Apr 2006
Posts: 536

PostPosted: Wed Jul 04, 2007 5:26 pm    Post subject: Reply with quote

jLo wrote:
OK, I see that one, but what about one that
links the 46 at R8C5 with the 46 at R4C7?

Code:
 *-------------------------------------------*
 | 9  7   18  | 18  3    2   | 5     6   4   |
 | 6  18  3   | 4   159  15  | 28    29  7   |
 | 4  5   2   | 89  7    6   | 38    1   39  |
 |------------+--------------+---------------|
 | 2  16  9   | 7   145  3   |#46    8   56  |
 | 7  68  18  | 19  245  45  | 2346  35  39  |
 | 3  4   5   | 6   29   8   | 7     29  1   |
 |------------+--------------+---------------|
 | 5  9   47  | 2   146  14  |#36   #37  8   |
 | 8  2   47  | 3  #46   9   | 1    #57 #56  |
 | 1  3   6   | 5   8    7   | 9     4   2   |
 *-------------------------------------------*
Either r4c7=4
or (r4c7=6 => r7c7=3 => r7c8=7 => r8c8=5 => r8c9=6 =>) r8c5=4
=> r4c5<>4
Code:
 *------------------------------------------*
 | 9  7   18  | 18  3    2   | 5    6   4   |
 | 6 #18  3   | 4   159 #15  | 28   29  7   |
 | 4  5   2   | 89  7    6   | 38   1   39  |
 |------------+--------------+--------------|
 | 2 #16  9   | 7  #15   3   | 4    8   56  |
 | 7 #68  18  | 19  245  45  | 236  35  39  |
 | 3  4   5   | 6   29   8   | 7    29  1   |
 |------------+--------------+--------------|
 | 5  9   47  | 2   146  14  | 36   37  8   |
 | 8  2   47  | 3   46   9   | 1    57  56  |
 | 1  3   6   | 5   8    7   | 9    4   2   |
 *------------------------------------------*
Here there is an xy-wing (pivot r5c6), that eliminates 1 in r7c5, which leads to the BUG grid.
Or another xy-chain to eliminate 5 in r2c5:
Either r2c6=5
or (r2c6=1 => r2c2=8 => r5c2=6 => r4c2=1 =>) r4c5=5
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