| View previous topic :: View next topic |
| Author |
Message |
kragzy
Joined: 01 May 2007
Posts: 112
Location: Australia
|
 Posted: Wed Oct 08, 2008 11:10 pm Post subject: Oct 9 VH |
 |
|
| After a messy and laborious clean up, a simple X-wing solves it. |
|
| Back to top |
|
 |
crunched
Joined: 05 Feb 2008
Posts: 168
|
| Posted: Thu Oct 09, 2008 2:07 am Post subject: |
|
|
| Code: |
+-----------------+--------------+---------------+
| 2348 248 1 | 6 39 7 | 248 5 2349 |
| 7 5 48 | 139 2 1349 | 148 3489 6 |
| 234 6 9 | 5 8 134 | 124 7 1234 |
+-----------------+--------------+---------------+
| 128 1278 5 | 4 137 6 | 9 238 237 |
| 6 9 478 | 38 37 2 | 478 1 5 |
| 1248 12478 3 | 189 179 5 | 6 248 247 |
+-----------------+--------------+---------------+
| 12489 3 248 | 7 6 189 | 5 249 1249 |
| 5 127 27 | 139 4 139 | 127 6 8 |
| 1489 1478 6 | 2 5 189 | 3 49 1479 |
+-----------------+--------------+---------------+
|
Play this puzzle online at the Daily Sudoku site
An X-wing of 7 in columns 3 & 7.
Is that all one has to find?
I had to find another x-wing to solve this. |
|
| Back to top |
|
|
arkietech
Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA
|
| Posted: Thu Oct 09, 2008 3:21 am Post subject: |
|
|
| Still waiting for the puzzle here in Arkansas |
|
| Back to top |
|
|
nataraj
Joined: 03 Aug 2007
Posts: 1048
Location: near Vienna, Austria
|
| Posted: Thu Oct 09, 2008 5:51 am Post subject: |
|
|
| crunched wrote: |
An X-wing of 7 in columns 3 & 7.
Is that all one has to find?
|
crunched,
In your grid, there is a naked triple (1,2,7) in row 8, which leads to a few more cells being solved (1 in r2c4, 4 in r3c3), but yes, the x-wing 7 alone solves the puzzle (this seems to be one of the rare cases where there is exactly one possible "advanced" step)
There is also an x-wing (4) but that one is not effective: I did a quick computer check, and after an xyz wing it was xy-chains of at least 6 steps.
Not a puzzle for x-wing haters... |
|
| Back to top |
|
|
keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
|
| Posted: Thu Oct 09, 2008 8:14 am Post subject: |
|
|
After basics: | Code: | +-------------------+-------------------+-------------------+
| 2348 248 1 | 6 39 7 |2-48 5 2349 |
| 7 5 48@ | 1 2 39 | 48@ 39 6 |
| 23 6 9 | 5 8 4 | 12 7 123 |
+-------------------+-------------------+-------------------+
| 128 1278 5 | 4 17 6 | 9 238 237 |
| 6 9 478@ | 38 37 2 | 47@ 1 5 |
| 1248 12478 3 | 89 179 5 | 6 248 247 |
+-------------------+-------------------+-------------------+
| 1489 3 2-48 | 7 6 18 | 5 249 1249 |
| 5 17 27 | 39 4 39 | 127 6 8 |
| 1489 1478 6 | 2 5 18 | 3 49 1479 |
+-------------------+-------------------+-------------------+ |
The X-wing @ takes out <4> in R1C7 and R5C3.
Those two cells are now a double W-wing (Remote Naked Pair), connected by the strong links in R2 aA and R8 bB: | Code: | +-------------------+-------------------+-------------------+
| 2348 248 1 | 6 39 7 | 28a 5 2349 |
| 7 5 48a | 1 2 39 | 48A 39 6 |
| 23 6 9 | 5 8 4 |1-2 7 123 |
+-------------------+-------------------+-------------------+
| 128 1278 5 | 4 17 6 | 9 238 237 |
| 6 9 47-8 | 38 37 2 | 47 1 5 |
| 1248 12478 3 | 89 179 5 | 6 248 247 |
+-------------------+-------------------+-------------------+
| 1489 3 28b | 7 6 18 | 5 249 1249 |
| 5 17 27B | 39 4 39 | 127b 6 8 |
| 1489 1478 6 | 2 5 18 | 3 49 1479 |
+-------------------+-------------------+-------------------+ |
With coloring (transporting), it takes out <2> in R3C7 and <8> in R5C3.
Solving the puzzle.
Keith |
|
| Back to top |
|
|
keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
|
| Posted: Thu Oct 09, 2008 8:25 am Post subject: |
|
|
| arkietech wrote: | | Still waiting for the puzzle here in Arkansas |
Dan, you can get the puzzle by clicking on the current puzzle it to get the printable PDF version. Change the date in the URL to "tomorrow", and the puzzle will display.
This only works to get you the puzzle after it is made available in time zones like New Zealand, which is sometime in the morning here in the USA.
Keith |
|
| Back to top |
|
|
arkietech
Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA
|
| Posted: Thu Oct 09, 2008 11:24 am Post subject: |
|
|
| keith wrote: | | [...Change the date in the URL to "tomorrow", and the puzzle will display... |
Thanks I will try it.
Not many ways to go on this one. x-wing(7) solves it. |
|
| Back to top |
|
|
crunched
Joined: 05 Feb 2008
Posts: 168
|
| Posted: Thu Oct 09, 2008 3:32 pm Post subject: |
|
|
| nataraj wrote: |
In your grid, there is a naked triple (1,2,7) in row 8, which leads to a few more cells being solved (1 in r2c4, 4 in r3c3), but yes, the x-wing 7 alone solves the puzzle (this seems to be one of the rare cases where there is exactly one possible "advanced" step)
There is also an x-wing (4) but that one is not effective: I did a quick computer check, and after an xyz wing it was xy-chains of at least 6 steps.
Not a puzzle for x-wing haters... |
| Code: |
+-----------------+-----------+---------------+
| 2348 248 1 | 6 9 7 | 248 5 234 |
| 7 5 48 | 13 2 134 | 148 3489 6 |
| 234 6 9 | 5 8 134 | 124 7 1234 |
+-----------------+-----------+---------------+
| 128 1278 5 | 4 17 6 | 9 238 237 |
| 6 9 47 | 8 3 2 | 47 1 5 |
| 1248 12478 3 | 9 17 5 | 6 248 247 |
+-----------------+-----------+---------------+
| 12489 3 248 | 7 6 189 | 5 249 1249 |
| 5 127 27 | 13 4 139 | 127 6 8 |
| 1489 1478 6 | 2 5 189 | 3 49 1479 |
+-----------------+-----------+---------------+
|
Play this puzzle online at the Daily Sudoku site
After a little cleanup from the 7 x-wing, a 9 x-wing (columns 1,9) really opened it up for me. (Or is the expression closed it up?). See grid above. |
|
| Back to top |
|
|
Florida Bob
Joined: 25 Jul 2007
Posts: 12
|
| Posted: Thu Oct 09, 2008 4:00 pm Post subject: |
|
|
| I may be blind today but I don't see the x-wing in Col. 3 & 7. Could someone be more descriptive. Also, how did you eliminate the 8 in R5 C3? |
|
| Back to top |
|
|
Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
|
| Posted: Thu Oct 09, 2008 4:52 pm Post subject: |
|
|
| Florida Bob wrote: | | I may be blind today but I don't see the x-wing in Col. 3 & 7. Could someone be more descriptive. Also, how did you eliminate the 8 in R5 C3? |
Note that in both columns 3 and 7 that 7s appear in only rows 5 and 8, thus the X-Wing.
As to the elimination of the 8, see Keith's first post in this thread. |
|
| Back to top |
|
|
daj95376
Joined: 23 Aug 2008
Posts: 3854
|
| Posted: Thu Oct 09, 2008 5:57 pm Post subject: |
|
|
| Florida Bob wrote: | | I may be blind today but I don't see the x-wing in Col. 3 & 7. Could someone be more descriptive. Also, how did you eliminate the 8 in R5 C3? |
Original PM as posted by crunched.
| Code: | +-----------------+--------------+---------------+
| 2348 248 1 | 6 39 7 | 248 5 2349 |
| 7 5 48 | 139 2 1349 | 148 3489 6 |
| 234 6 9 | 5 8 134 | 124 7 1234 |
+-----------------+--------------+---------------+
| 128 1278 5 | 4 137 6 | 9 238 237 |
| 6 9 478 | 38 37 2 | 478 1 5 |
| 1248 12478 3 | 189 179 5 | 6 248 247 |
+-----------------+--------------+---------------+
| 12489 3 248 | 7 6 189 | 5 249 1249 |
| 5 127 27 | 139 4 139 | 127 6 8 |
| 1489 1478 6 | 2 5 189 | 3 49 1479 |
+-----------------+--------------+---------------+
|
After basic techniques, there are two X-Wings exposed. One is for (4) and can be found in rows 2 & 5. The other is for (7) and can be found in columns 3 and 7.
| Code: | (4) X-Wing r25\c37 => [r1c7],r7c3]<>4
*--------------------------------------------------------------------*
| 2348 248 1 | 6 39 7 | 28-4 5 2349 |
| 7 5 *48 | 1 2 39 |*48 39 6 |
| 23 6 9 | 5 8 4 | 12 7 123 |
|----------------------+----------------------+----------------------|
| 128 1278 5 | 4 17 6 | 9 238 237 |
| 6 9 *478 | 38 37 2 |*47 1 5 |
| 1248 12478 3 | 89 179 5 | 6 248 247 |
|----------------------+----------------------+----------------------|
| 1489 3 28-4 | 7 6 18 | 5 249 1249 |
| 5 17 27 | 39 4 39 | 127 6 8 |
| 1489 1478 6 | 2 5 18 | 3 49 1479 |
*--------------------------------------------------------------------*
|
| Code: | (7) X-Wing c37\r58 => [r5c5],[r8c2]<>7
*--------------------------------------------------------------------*
| 2348 248 1 | 6 39 7 | 248 5 2349 |
| 7 5 48 | 1 2 39 | 48 39 6 |
| 23 6 9 | 5 8 4 | 12 7 123 |
|----------------------+----------------------+----------------------|
| 128 1278 5 | 4 17 6 | 9 238 237 |
| 6 9 *478 | 38 3-7 2 |*47 1 5 |
| 1248 12478 3 | 89 179 5 | 6 248 247 |
|----------------------+----------------------+----------------------|
| 1489 3 248 | 7 6 18 | 5 249 1249 |
| 5 1-7 *27 | 39 4 39 |*127 6 8 |
| 1489 1478 6 | 2 5 18 | 3 49 1479 |
*--------------------------------------------------------------------*
|
I'm not going to try and explain keith's elimination [r5c3]<>8. However, please note that cells [r5c3] & [r5c7] are in both X-Wings. If [r5c3]=8, then the X-Wing cells for (4) would force [r5c7]=4. At the same time, the X-Wing cells for (7) would force [r5c7]=7 -- a contradiction. Thus, we can conclude that [r5c3]<>8. |
|
| Back to top |
|
|
Florida Bob
Joined: 25 Jul 2007
Posts: 12
|
| Posted: Thu Oct 09, 2008 6:25 pm Post subject: |
|
|
Thanks for the replies.
I guess my problem was more an issue of definitions. I think of an X wing following an AB, BC, AC format. The elimination in row 5 was the results of small chains, which I did not see. |
|
| Back to top |
|
|
keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
|
| Posted: Thu Oct 09, 2008 7:18 pm Post subject: |
|
|
| Florida Bob wrote: | Thanks for the replies.
I guess my problem was more an issue of definitions. I think of an X wing following an AB, BC, AC format. The elimination in row 5 was the results of small chains, which I did not see. |
Bob,
An X-wing starts with the same candidate on four corners of a rectangle.
An XY-wing is XY, YZ, XZ, or AB, BC, AC.
Keith |
|
| Back to top |
|
|
keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
|
| Posted: Thu Oct 09, 2008 7:33 pm Post subject: |
|
|
| daj95376 wrote: |
I'm not going to try and explain keith's elimination [r5c3]<>8. |
Let me do it again: | Code: | +-------------------+-------------------+-------------------+
| 2348 248 1 | 6 39 7 | 28a 5 2349 |
| 7 5 48c | 1 2 39 | 48b 39 6 |
| 23 6 9 | 5 8 4 | 12 7 123 |
+-------------------+-------------------+-------------------+
| 128 1278 5 | 4 17 6 | 9 238 237 |
| 6 9 47-8 | 38 37 2 | 47 1 5 |
| 1248 12478 3 | 89 179 5 | 6 248 247 |
+-------------------+-------------------+-------------------+
| 1489 3 28d | 7 6 18 | 5 249 1249 |
| 5 17 27@ | 39 4 39 | 127@ 6 8 |
| 1489 1478 6 | 2 5 18 | 3 49 1479 |
+-------------------+-------------------+-------------------+ |
Cells a and d are a pair, <28>. They are connected by the strong link on <2>, @ in R8. This is a W-wing: Any cell that sees both a and d cannot be <8>. One or both of a and d is <8>. There are no direct eliminations to make.
Now, the coloring, or transporting part: Note the strong links on <8> ab in C7, and bc in R2. If a is <8>, b is not <8>, c is <8>. Any cell that sees both c and d is not <8>, and you can eliminate <8> from R5C3 as shown.
Keith |
|
| Back to top |
|
|
cgordon
Joined: 04 May 2007
Posts: 769
Location: ontario, canada
|
| Posted: Thu Oct 09, 2008 9:28 pm Post subject: |
|
|
| Quote: | | After a messy and laborious clean up, a simple X-wing solves it. |
This first post says it all. It was more challenging to find the naked 2's and 9's in the basics than some mickey mouse x-wing. That's my gripe for the day! Good Day Bruce. |
|
| Back to top |
|
|
daj95376
Joined: 23 Aug 2008
Posts: 3854
|
| Posted: Thu Oct 09, 2008 10:31 pm Post subject: |
|
|
| keith wrote: | | daj95376 wrote: | | I'm not going to try and explain keith's elimination [r5c3]<>8. |
Let me do it again: ... |
I hope this wasn't for my benefit. I understood ... I just refused to re-explain it -- especially when I had a short loop for the same elimination.
| Code: | [cloop__3]: -4r5c3 4-7r5c7 7r8c7 -7r8c3 7r5c3 => [r5c3]<>8
|
However, since the (manual) solutions in this forum shy away from (many) chains, fish, and a few other techniques, I spotted the overlapping X-Wings explanation and thought it was perfect. |
|
| Back to top |
|
|
kragzy
Joined: 01 May 2007
Posts: 112
Location: Australia
|
| Posted: Thu Oct 09, 2008 10:44 pm Post subject: |
|
|
| cgordon wrote: | | Quote: | | After a messy and laborious clean up, a simple X-wing solves it. |
This first post says it all. It was more challenging to find the naked 2's and 9's in the basics than some mickey mouse x-wing. That's my gripe for the day! Good Day Bruce. |
G'day polite American. |
|
| Back to top |
|
|
cgordon
Joined: 04 May 2007
Posts: 769
Location: ontario, canada
|
| Posted: Thu Oct 09, 2008 11:05 pm Post subject: |
|
|
| Quote: | | G'day polite American. |
American?? We're still part of the Empire mate. |
|
| Back to top |
|
|
keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
|
| Posted: Fri Oct 10, 2008 1:16 am Post subject: |
|
|
>> hope this wasn't for my benefit. I understood ...
No, in my quest to be a teacher, I will explain it again.
Keith |
|
| Back to top |
|
|
nataraj
Joined: 03 Aug 2007
Posts: 1048
Location: near Vienna, Austria
|
| Posted: Fri Oct 10, 2008 6:24 am Post subject: |
|
|
| nataraj wrote: |
this seems to be one of the rare cases where there is exactly one possible "advanced" step |
| keith wrote: | The X-wing @ takes out <4> in R1C7 and R5C3.
Those two cells are now a double W-wing (Remote Naked Pair), connected by the strong links in R2 aA and R8 bB: [...] With coloring (transporting), it takes out <2> in R3C7 and <8> in R5C3.
Solving the puzzle.
Keith |
I stand corrected - as I knew I would 
____
"Why'd you write it then?"
-
"It seemed like a good idea at the time"  |
|
| Back to top |
|
|
|
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
