View previous topic :: View next topic |
Author |
Message |
csc
Joined: 03 May 2007 Posts: 14
|
Posted: Wed May 30, 2007 11:33 am Post subject: 18 dec 06 an alternative route please |
|
|
I proceeded from below via:
xy chain r2c8 - r3c7 - r3c3 - r3c2 - r8c2, eliminating candidate 9 in r8c8, after which an xy wing: pivot 47 in r8c8 and pincers r9c8, r8c2, eliminating candidate 9 in r9c2, and so on.
When I asked for a hint from "play online", it gave a 7 in r7c7 (ie. eliminating the 8). One of the challenges I set myself for each puzzle (I'm sure other puzzlers set such challenges for themselves too) is to solve it in the most "economic" way, ie. using the simplest and most direct techniques possible (I admit simple and direct may be partly subjective terms). In this case I'm unable to find the route to eliminate the 8 in r7c7, so if someone could show me the alternative (and possibly more economic) route, I'd appreciate it.
Thanks
scchua
Code: |
+-------------+----------+--------------+
| 9 6 2 | 7 5 8 | 4 1 3 |
| 78 3 5 | 1 4 6 | 2 79 89 |
| 4 17 18 | 3 9 2 | 78 6 5 |
+-------------+----------+--------------+
| 1 2 9 | 5 7 4 | 3 8 6 |
| 6 5 4 | 8 3 9 | 1 2 7 |
| 3 8 7 | 6 2 1 | 9 5 4 |
+-------------+----------+--------------+
| 27 4 18 | 9 6 5 | 78 3 12 |
| 278 79 6 | 24 1 3 | 5 479 289 |
| 5 19 3 | 24 8 7 | 6 49 129 |
+-------------+----------+--------------+
|
|
|
Back to top |
|
![](templates/subSilver/images/spacer.gif) |
Steve R
Joined: 24 Oct 2005 Posts: 289 Location: Birmingham, England
|
Posted: Wed May 30, 2007 1:06 pm Post subject: |
|
|
The most direct route is to note the conjugates for 7 in rows 2 and 7.
Code: | +-------------+----------+--------------+
| 9 6 2 | 7 5 8 | 4 1 3 |
| 78* 3 5 | 1 4 6 | 2 79* 89 |
| 4 17 18 | 3 9 2 | 78 6 5 |
+-------------+----------+--------------+
| 1 2 9 | 5 7 4 | 3 8 6 |
| 6 5 4 | 8 3 9 | 1 2 7 |
| 3 8 7 | 6 2 1 | 9 5 4 |
+-------------+----------+--------------+
| 27* 4 18 | 9 6 5 | 78* 3 12 |
| 278 79 6 | 24 1 3 | 5 479 289 |
| 5 19 3 | 24 8 7 | 6 49 129 |
+-------------+----------+--------------+ |
As the first column cannot contain two 7s, one of r2c8 or r7c7 must contain a 7. So 7 can be eliminated from r8c8, placing it in r7c7.
Steve |
|
Back to top |
|
![](templates/subSilver/images/spacer.gif) |
Mogulmeister
Joined: 03 May 2007 Posts: 1151
|
Posted: Wed May 30, 2007 1:47 pm Post subject: |
|
|
Just to further add that what you have here is the conjugate pattern often known as a "skyscraper" on 7's.
Since the ends or pincers are both pointing to r3c7 and r8c8 these can be eliminated. |
|
Back to top |
|
![](templates/subSilver/images/spacer.gif) |
csc
Joined: 03 May 2007 Posts: 14
|
Posted: Thu May 31, 2007 12:25 am Post subject: |
|
|
Thanks, Steve and Mogulmeister.
Yes, a definitely more elegant route than my roundabout one.
regards
scchua |
|
Back to top |
|
![](templates/subSilver/images/spacer.gif) |
|
|
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
|