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Clement
Joined: 24 Apr 2006 Posts: 1111 Location: Dar es Salaam Tanzania
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Posted: Mon Dec 31, 2012 10:58 pm Post subject: Jan 1 VH |
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Code: |
+--------------+-------------+---------+
| *18 6 *18 | 3 7 9 | 4 5 2 |
| 9 3 4 | 2 5 8 | 1 6 7 |
| 2 7 5 | 6 1 4 | 9 3 8 |
+--------------+-------------+---------+
| 78 1 2 | 478 34-8 5 | 6 9 34 |
| 3 45 67 | 9 46 2 | 57 8 1 |
| 5678 458 9 | 1 3468 37 | 57 2 34 |
+--------------+-------------+---------+
| *17-8 9 *17-8 | -78 2 6 | 3 4 5 |
| 5678 58 678 | 478 348 37 | 2 1 9 |
| 4 2 3 | 5 9 1 | 8 7 6 |
+--------------+-------------+---------+
| Type 4 UR 18 in r17c13; r7c13<>8 opens an
xy-wing 47-37-34 pivoted in r6c6; r4c9<>4 which solves it. |
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arkietech
Joined: 31 Jul 2008 Posts: 1834 Location: Northwest Arkansas USA
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Posted: Tue Jan 01, 2013 12:42 am Post subject: |
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Code: | *-----------------------------------------------------------*
| 18 6 18 | 3 7 9 | 4 5 2 |
| 9 3 4 | 2 5 8 | 1 6 7 |
| 2 7 5 | 6 1 4 | 9 3 8 |
|-------------------+-------------------+-------------------|
| 78 1 2 | 478 348 5 | 6 9 34 |
| 3 b45 7-6 | 9 c46 2 | 57 8 1 |
|a56 458 9 | 1 3468 37 | 57 2 34 |
|-------------------+-------------------+-------------------|
| 178 9 178 | 78 2 6 | 3 4 5 |
| 56 58 678 | 478 348 37 | 2 1 9 |
| 4 2 3 | 5 9 1 | 8 7 6 |
*-----------------------------------------------------------*
xy-wing
(6=5)r6c1-(5=4)r5c2-(4=6)r5c5 => -6r5c5; stte |
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hughwill
Joined: 05 Apr 2010 Posts: 424 Location: Birmingham UK
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Posted: Tue Jan 01, 2013 11:03 am Post subject: Jan 1 VH |
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Nice to start a new year with a classic VH.
The double 567 XY wing does it in one as well (pivot r4c3 or r5c1). |
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tlanglet
Joined: 17 Oct 2007 Posts: 2468 Location: Northern California Foothills
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Posted: Tue Jan 01, 2013 10:19 pm Post subject: |
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As already posted, this puzzle has a Type 4 UR(18)r17c13. These same four cells also offer a Type 2 UR(18) that results in the identical deletions; neither completes the puzzle. However a one step solution is achievable from a third perspective: AUR(18)r17c13.
Looking at the external implications, we find that only two constraints are necessary to prevent the deadly pattern: r4c1=8 & r8c3=8.
1): If r4c1=8, then r4c1<>7, then r5c3=7, then r5c3<>6, then r5c5=6, then r5c5<>4, then r5c2=4;
2): If r8c3=8, then r8c2=5, then r8c1=6, then r6c1=5, then r5c2=4;
Thus, both conditions to prevent the DP provide the same result, r5c2=4, which completes the puzzle.
Ted |
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hughwill
Joined: 05 Apr 2010 Posts: 424 Location: Birmingham UK
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Posted: Wed Jan 02, 2013 10:37 am Post subject: |
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Quote: | As already posted, this puzzle has a Type 4 UR (18)r17c13. These same four cells also offer a Type 2 UR (18 ) that results in the identical deletions; neither completes the puzzle. However a one step solution is achievable from a third perspective: AUR(18)r17c13.
Looking at the external implications, we find that only two constraints are necessary to prevent the deadly pattern: r4c1=8 & r8c3=8.
1): If r4c1=8, then r4c1<>7, then r5c3=7, then r5c3<>6, then r5c5=6, then r5c5<>4, then r5c2=4;
2): If r8c3=8, then r8c2=5, then r8c1=6, then r6c1=5, then r5c2=4;
Thus, both conditions to prevent the DP provide the same result, r5c2=4, which completes the puzzle.
Ted |
Excellent! |
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