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LAT/Freep 22-Feb-2008

 
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Asellus



Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA
PostPosted: Sat Feb 23, 2008 4:46 am    Post subject: LAT/Freep 22-Feb-2008 Reply with quote
For those so inclined:
Code:
+-------+-------+-------+
| . . . | 5 . 8 | . . 9 |
| . 7 . | . 9 . | . . . |
| . 5 . | 7 . 4 | . 3 . |
+-------+-------+-------+
| 3 6 . | 2 . . | . . . |
| . . 7 | . . . | 5 . . |
| . . . | . . 6 | . 4 7 |
+-------+-------+-------+
| . 4 . | 8 . 9 | . 7 . |
| . . . | . 6 . | . 1 . |
| 9 . . | 1 . 3 | . . . |
+-------+-------+-------+
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Earl



Joined: 30 May 2007
Posts: 677
Location: Victoria, KS
PostPosted: Sat Feb 23, 2008 5:01 am    Post subject: LA Reply with quote
A skyscraper (2) does it.

Earl
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Asellus



Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA
PostPosted: Sun Feb 24, 2008 12:34 am    Post subject: Reply with quote
It's true that that Skyscraper makes easy work of it.

However, this puzzle has some interesting Deadly Pattern solutions. First:
Code:

+--------------+-----------+---------------+
| 246  1   246 | 5   3   8 | 7    26   9   |
| 8    7   3   | 6   9   2 |@14   5   @14  |
| 26   5   9   | 7   1   4 |@268  3   @68  |
+--------------+-----------+---------------+
| 3    6   45  | 2   45  7 |@18   9   @18  |
| 24   89  7   | 39  48  1 | 5    26   36  |
| 15   89  125 | 39  58  6 | 23   4    7   |
+--------------+-----------+---------------+
| 15   4   156 | 8   2   9 | 36   7    356 |
| 7    3   8   | 4   6   5 | 9    1    2   |
| 9    2   56  | 1   7   3 |@46   8   @456 |
+--------------+-----------+---------------+

The cells marked @ contain a {14}-{68}-{18}-{46} DP. Thus, r3c7 is <2> and/or r9c9 is <5>. If r3c7 is <2>, then r3c9 is <8>. But, if r9c9 is <5>, then c9 has a {36} locked pair and r3c9 is <8>. So, r3c9 is <8>.

This leads to this point:
Code:

+---------------+-----------+-------------+
| 246  1    24  | 5   3   8 | 7   26  9   |
| 8    7    3   | 6   9   2 | 1   5   4   |
| 26   5    9   | 7   1   4 | 26  3   8   |
+---------------+-----------+-------------+
| 3    6    45  | 2   45  7 | 8   9   1   |
| 24   89   7   | 39  48  1 | 5   26  36  |
|a15   89  a125 | 39  58  6 | 23  4   7   |
+---------------+-----------+-------------+
|a15   4  ab156 | 8   2   9 | 36  7  b356 |
| 7    3    8   | 4   6   5 | 9   1   2   |
| 9    2   b56  | 1   7   3 | 4   8  b56  |
+---------------+-----------+-------------+

There is a {15} UR marked "a" and a {56} UR marked "b". There are many ways to resolve this. But, perhaps most interesting is to note that if r7c3 is <6>, then r7c9 must be <3> to avoid the UR. But this is impossible since it results in two <3>s in r7. So, we know instantly that r7c9 is <3> and r6c3 is <2>.
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storm_norm



Joined: 18 Oct 2007
Posts: 1741
PostPosted: Sun Feb 24, 2008 3:30 am    Post subject: Reply with quote
I saw the 1,5 UR and automatically thought type 3, but no, no other 26 cell in col 3. so I moved on to the coloring on 2 and solved it.
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Asellus



Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA
PostPosted: Sun Feb 24, 2008 9:40 am    Post subject: Reply with quote
That {15} UR is a Type 4. The <1>s in c3 are strongly linked. Thus, <5>s can be removed from r67c3. But then, there wouldn't be that interesting bit with the {56} UR later! Wink
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Victor



Joined: 29 Sep 2005
Posts: 207
Location: NI
PostPosted: Sun Feb 24, 2008 11:19 am    Post subject: Reply with quote
This is a very easy puzzle by Asellus standards (kill 2s or W-wing or . . .), & so I thought we were meant to spot the pattern in R67C37.
Code:
+--------------+-----------+---------------+
| 246  1   246 | 5   3   8 | 7    26   9   |
| 8    7   3   | 6   9   2 | 14   5    14  |
| 26   5   9   | 7   1   4 | 268  3    68  |
+--------------+-----------+---------------+
| 3    6   45  | 2   45  7 | 18   9    18  |
| 24   89  7   | 39  48  1 | 5    26   36  |
| 15   89 *12  | 39  58  6 |*23   4    7   |
+--------------+-----------+---------------+
| 15   4  *16  | 8   2   9 |*36   7    356 |
| 7    3   8   | 4   6   5 | 9    1    2   |
| 9    2   56  | 1   7   3 | 46   8    456 |
+--------------+-----------+---------------+


The 12,23,36,16 form a closed XY-chain, which as far as I can see would eliminate any other 2s along R6, etc. In this case, the 6 in R7C9 is killed.
Never seen this before. Special name? Nice anyway!
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Asellus



Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA
PostPosted: Mon Feb 25, 2008 10:07 pm    Post subject: Reply with quote
Victor wrote:
Never seen this before. Special name? Nice anyway!

XY Loop. And yes, they are nice. There are two examples in the latter part of this post.
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