| View previous topic :: View next topic |
| Author |
Message |
Earl
Joined: 30 May 2007
Posts: 677
Location: Victoria, KS
|
 Posted: Fri Dec 12, 2008 3:00 am Post subject: Dec 12 VH |
 |
|
Very tricky !
You may be tempted to use the apparent UR (73), but it is not valid.
However, you can use the 73 chain to eliminate both 7&3 from R2C9, which solves the puzzle in one step. Otherwise it requires multiple steps with coloring and wings.
Earl |
|
| Back to top |
|
 |
Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
|
| Posted: Fri Dec 12, 2008 4:47 am Post subject: |
|
|
| I used the remote pairs on 37 but still needed an X-Wing. |
|
| Back to top |
|
|
crunched
Joined: 05 Feb 2008
Posts: 168
|
| Posted: Fri Dec 12, 2008 5:18 am Post subject: |
|
|
Here is as far as I could get. I think all the basics are gone. Ask for a hint, and I don't know how that works.
It will be interesting to see what I have missed in the x-xy-xyz solution.
| Code: |
+------------+--------------+-----------+
| 9 6 5 | 27 4 23 | 237 8 1 |
| 37 8 4 | 267 1 5 | 237 9 367 |
| 2 37 1 | 8 79 369 | 5 4 367 |
+------------+--------------+-----------+
| 47 49 6 | 3 279 129 | 17 5 8 |
| 5 2 379 | 79 8 19 | 137 6 4 |
| 1 37 8 | 5 6 4 | 9 2 37 |
+------------+--------------+-----------+
| 346 49 39 | 2469 29 7 | 8 1 5 |
| 68 5 2 | 1 3 68 | 4 7 9 |
| 478 1 79 | 49 5 89 | 6 3 2 |
+------------+--------------+-----------+
|
Play this puzzle online at the Daily Sudoku site |
|
| Back to top |
|
|
Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
|
| Posted: Fri Dec 12, 2008 5:58 am Post subject: |
|
|
| crunched wrote: | Here is as far as I could get. I think all the basics are gone. Ask for a hint, and I don't know how that works.
It will be interesting to see what I have missed in the x-xy-xyz solution.
| Code: |
+------------+--------------+-----------+
| 9 6 5 | 27 4 23 | 237 8 1 |
| 37 8 4 | 267 1 5 | 237 9 367 |
| 2 37 1 | 8 79 369 | 5 4 367 |
+------------+--------------+-----------+
| 47 49 6 | 3 279 129 | 17 5 8 |
| 5 2 379 | 79 8 19 | 137 6 4 |
| 1 37 8 | 5 6 4 | 9 2 37 |
+------------+--------------+-----------+
| 346 49 39 | 2469 29 7 | 8 1 5 |
| 68 5 2 | 1 3 68 | 4 7 9 |
| 478 1 79 | 49 5 89 | 6 3 2 |
+------------+--------------+-----------+
|
Play this puzzle online at the Daily Sudoku site |
It gives a hint of 2 in r7c5. The XY-Wing on 792 pivoted in r3c5 takes out the 2 from r7c4, leaving just one 2 remaining in box 8. |
|
| Back to top |
|
|
cgordon
Joined: 04 May 2007
Posts: 769
Location: ontario, canada
|
| Posted: Fri Dec 12, 2008 2:10 pm Post subject: |
|
|
It's all about ERs on <7>.
Using the strong links in C5, R1 and R6 we can remove the <7> in R4C1, R4C7 and R2C9. So much easier than wings and things. |
|
| Back to top |
|
|
bette
Joined: 22 Jan 2006
Posts: 6
Location: Fredericton, NB Canada
|
| Posted: Fri Dec 12, 2008 5:58 pm Post subject: |
|
|
| I'm confused....I thought I had ER's figured out but guess not. I thought R3C2, R3C9, R6C2 and R6C9 formed a unique ER with 37 and therefore R3C9 would have to be 6. I learned this is wrong but don't understand why. Can someone please explain?? |
|
| Back to top |
|
|
Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
|
| Posted: Fri Dec 12, 2008 6:25 pm Post subject: |
|
|
| bette wrote: | | I'm confused....I thought I had ER's figured out but guess not. I thought R3C2, R3C9, R6C2 and R6C9 formed a unique ER with 37 and therefore R3C9 would have to be 6. I learned this is wrong but don't understand why. Can someone please explain?? |
I think you mean UR rather than ER. Unique Rectangle vs. Empty Rectangle. You've got the right idea with those 37 cells, except the four cells are in four different boxes and UR theory is valid only when the UR is confined to two boxes. This is a good primer on URs.
http://www.sudoku.com/boards/viewtopic.php?p=29105#29105 |
|
| Back to top |
|
|
bette
Joined: 22 Jan 2006
Posts: 6
Location: Fredericton, NB Canada
|
| Posted: Fri Dec 12, 2008 8:11 pm Post subject: |
|
|
| ohhhhhh..ok, thanks Marty. Guess I was just lucky any time before when I used the UR to solve a puzzle |
|
| Back to top |
|
|
storm_norm
Joined: 18 Oct 2007
Posts: 1741
|
| Posted: Fri Dec 12, 2008 9:12 pm Post subject: |
|
|
cgordon,
that was very nice pointing out the ER's
i'd also like to add that there are some overlying ER's on 3 as well.
which happens to included that remote pair.
| Quote: | | It will be interesting to see what I have missed in the x-xy-xyz solution. |
yes. no one has posted the VH route yet.
| Quote: | the xy-wing eliminating 2
then after some basics... there are simultaneous moves present... x-wing on 3 and a xyz-wing in box 3. |
lots of moves present as the puzzle progresses. there is also a UR {2,7}r12c47 at one point. |
|
| Back to top |
|
|
keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
|
| Posted: Fri Dec 12, 2008 10:37 pm Post subject: |
|
|
After basics: | Code: | +----------------+----------------+----------------+
| 9 6 5 | 27 4 23 | 237 8 1 |
| 37 8 4 | 267 1 5 | 237 9 367 |
| 2 37 1 | 8 79 369 | 5 4 367 |
+----------------+----------------+----------------+
| 47 49 6 | 3 279 129 | 17 5 8 |
| 5 2 379 | 79 8 19 | 137 6 4 |
| 1 37 8 | 5 6 4 | 9 2 37 |
+----------------+----------------+----------------+
| 346 49 39 | 2469 29 7 | 8 1 5 |
| 68 5 2 | 1 3 68 | 4 7 9 |
| 478 1 79 | 49 5 89 | 6 3 2 |
+----------------+----------------+----------------+ |
The remote pair <37> that solves R2C9 is all that is needed.
An alternative is XY-, X-, XYZ-wing which, interestingly, ends up solving the same cell to finish the puzzle.
Keith |
|
| Back to top |
|
|
Wendy W
Joined: 04 Feb 2008
Posts: 144
|
| Posted: Fri Dec 12, 2008 11:39 pm Post subject: |
|
|
| It was a three-stepper for me: an xy-wing <279>, then an xyz-wing <237> and finally a x-wing on 3. A nice puzzle! |
|
| Back to top |
|
|
|
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
