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Puzzle NR 09/11/12 -- UR Demo

 
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daj95376



Joined: 23 Aug 2008
Posts: 3854
PostPosted: Thu Nov 12, 2009 9:37 pm    Post subject: Puzzle NR 09/11/12 -- UR Demo Reply with quote
Code:
 +-----------------------+
 | 3 . 9 | . . . | . . 2 |
 | . . . | 6 1 . | . . 3 |
 | 6 . . | . . . | 7 4 . |
 |-------+-------+-------|
 | . 7 . | . . . | . . . |
 | . 9 . | . 4 . | . 3 . |
 | . . . | . . 1 | 6 . 7 |
 |-------+-------+-------|
 | . . 8 | . . 7 | . . 6 |
 | . . 1 | . 8 . | . 2 9 |
 | 9 6 . | . . 4 | 1 7 . |
 +-----------------------+

Play this puzzle online at the Daily Sudoku site

After basics, there are two overlapping UR patterns that prove useful.

Code:
 <34> UR r78c27
 (2                  -  3)r7c2 => r7c2<>3
 (5)r8c2 - (5=3)r9c3 - (3)r7c2 => r7c2<>3

 alternately: by taking advantage of strong links used as weak links

 r7c2=3 <=> r7c7=4 <=> r8c7=3 <=> r8c2=4, <34> DP r78c27  =>  r7c2<>3, r8c2<>4
 +-----------------------------------------------------------------------+
 |  3      1      9      |  4      7      58     |  58     6      2      |
 |  248    248    7      |  6      1      258    |  589    89     3      |
 |  6      258    25     |  2389   23     39     |  7      4      1      |
 |-----------------------+-----------------------+-----------------------|
 |  258    7      23     |  23589  6      39     |  289    1      4      |
 |  1      9      6      |  7      4      28     |  28     3      5      |
 |  258    238    4      |  23589  235    1      |  6      89     7      |
 |-----------------------+-----------------------+-----------------------|
 |  24    *34+2   8      |  1      9      7      | *34     5      6      |
 |  7     *34+5   1      |  35     8      6      | *34     2      9      |
 |  9      6      35     |  235    235    4      |  1      7      8      |
 +-----------------------------------------------------------------------+
 # 55 eliminations remain

Code:
 <24> UR r27c12 (Type 2)  =>  r2c12=8  =>  r2c678<>8   (cracks puzzle)
 +-----------------------------------------------------------------------+
 |  3      1      9      |  4      7      58     |  58     6      2      |
 | *24+8  *24+8   7      |  6      1      258    |  589    89     3      |
 |  6      258    25     |  2389   23     39     |  7      4      1      |
 |-----------------------+-----------------------+-----------------------|
 |  258    7      23     |  23589  6      39     |  289    1      4      |
 |  1      9      6      |  7      4      28     |  28     3      5      |
 |  258    238    4      |  23589  235    1      |  6      89     7      |
 |-----------------------+-----------------------+-----------------------|
 | *24    *24     8      |  1      9      7      |  3      5      6      |
 |  7      35     1      |  35     8      6      |  4      2      9      |
 |  9      6      35     |  235    235    4      |  1      7      8      |
 +-----------------------------------------------------------------------+
 # 51 eliminations remain

It's tempting to combine the two URs and make a single step solution for the first PM.

(8)r2c8 - <24>URr27c12[(8)r2c12 = (3)r8c2], <34>DPr78c27 => r2c8<>8

Even without these two URs, it should still be a fun puzzle.
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arkietech



Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA
PostPosted: Thu Nov 12, 2009 9:59 pm    Post subject: Reply with quote
ur not needed:
Quote:
w-wing 23 solves it quick
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Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
PostPosted: Thu Nov 12, 2009 11:21 pm    Post subject: Reply with quote
I used two different XY-Wings of 253, the 2nd one with pincer transport in addition to the direct eliminations. Then the 24 UR in boxes 17. In my grid, both roof cells contained 2458 and the 58 pseudo cell combined with two other cells in row 2 to form a 589 triple, finishing the puzzle.
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tlanglet



Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
PostPosted: Thu Nov 12, 2009 11:32 pm    Post subject: Reply with quote
Another quickie:

Quote:
xy-wing -239 with vertex 39 in r4c6, pincer 23 in r4c3 and pincer 29 a pseudocell in r3c56 deletes 2 in r3c3

Ted
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tlanglet



Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
PostPosted: Thu Nov 12, 2009 11:45 pm    Post subject: Reply with quote
arkietech wrote:
ur not needed:
Quote:
w-wing 23 solves it quick

I was just looking at your solution and I believe that we both made the identical deletion using different techniques. Interesting........

Ted
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arkietech



Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA
PostPosted: Fri Nov 13, 2009 2:26 am    Post subject: Reply with quote
tlanglet wrote:
I was just looking at your solution and I believe that we both made the identical deletion using different techniques. Interesting........

What goes around comes around. Very Happy I find this to happen a lot.
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