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VH: Set A Puzzle 18

 
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daj95376



Joined: 23 Aug 2008
Posts: 3855

PostPosted: Sat Nov 08, 2008 4:15 pm    Post subject: VH: Set A Puzzle 18 Reply with quote

Code:
 +-----------------------+
 | 1 . 8 | 4 . . | 7 . 6 |
 | . 9 . | . 8 . | . 5 . |
 | 4 . . | . 2 6 | 1 8 . |
 |-------+-------+-------|
 | 9 . . | . . 2 | . . . |
 | . 8 7 | . 9 . | . . . |
 | . . 6 | 5 . . | 8 . . |
 |-------+-------+-------|
 | 8 . 9 | . . 4 | . . . |
 | . 5 3 | . . . | . 6 . |
 | 7 . . | . . . | . . . |
 +-----------------------+
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nataraj



Joined: 03 Aug 2007
Posts: 1029
Location: Vienna, Austria

PostPosted: Sat Nov 08, 2008 5:21 pm    Post subject: Reply with quote

After basics,
one UR type 1 (impossible to miss )
and a not-quite-so-obvious x-wing (7),

this is where I see an xy-wing (in fact, several xy-wings).
Code:

+--------------------------+--------------------------+--------------------------+
| 1       3       8        | 4       5       9        | 7       2       6        |
| 6       9       2        | 17      8       17       | 34      5       34       |
| 4       7       5        | 3       2       6        | 1       8       9        |
+--------------------------+--------------------------+--------------------------+
| 9       4       1        | 8       67      2        | 356     37      35       |
| 5       8       7        | 16      9       3        | 26      4       12       |
| 3       2       6        | 5       4       17       | 8       9       17       |
+--------------------------+--------------------------+--------------------------+
| 8       1       9        | 26      67      4        | 235     37      235      |
| 2       5       3        | 79      1       8        | 49      6       47       |
| 7       6       4        | 29      3       5        | 29      1       8        |
+--------------------------+--------------------------+--------------------------+

Is this the series "try it without xy-wing"?

Anyway, I'd go for the w-wing (6) r5c7=r7c4 (via SL (2) either in row 9 or col 9)
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Marty R.



Joined: 12 Feb 2006
Posts: 5175
Location: Rochester, NY, USA

PostPosted: Sat Nov 08, 2008 5:25 pm    Post subject: Reply with quote

I used the Type 1 UR, a finned swordfish on 7, XY-Wing on 194, then fin transport to finish it off.

I believe the finned swordfish was just the second one ever for me.

Nataraj's grid is further advanced than mine and two of the three cells in my XY-Wing are already solved.
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nataraj



Joined: 03 Aug 2007
Posts: 1029
Location: Vienna, Austria

PostPosted: Sat Nov 08, 2008 5:32 pm    Post subject: Reply with quote

I re-did the puzzle on my computer, just to make sure.
Up to here, nothing but basics and the UR.
The x-wing 7 (cols 5,8 ) is not very hard to spot. I believe you must overlooked something in the basics mire, Marty.


Code:

+--------------------------+--------------------------+--------------------------+
| 1       3       8        | 4       5       9        | 7       2       6        |
| 6       9       2        | 17      8       17       | 34      5       34       |
| 4       7       5        | 3       2       6        | 1       8       9        |
+--------------------------+--------------------------+--------------------------+
| 9       4       1        | 8       67      2        | 356     37      357      |
| 5       8       7        | 16      9       3        | 26      4       12       |
| 3       2       6        | 5       4       17       | 8       9       17       |
+--------------------------+--------------------------+--------------------------+
| 8       1       9        | 267     67      4        | 235     37      2357     |
| 2       5       3        | 79      1       8        | 49      6       47       |
| 7       6       4        | 29      3       5        | 29      1       8        |
+--------------------------+--------------------------+--------------------------+
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cgordon



Joined: 04 May 2007
Posts: 769
Location: ontario, canada

PostPosted: Sat Nov 08, 2008 5:40 pm    Post subject: Reply with quote

Same as Nataraj: unavoidable UR, x-wing, xy wing.
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daj95376



Joined: 23 Aug 2008
Posts: 3855

PostPosted: Sat Nov 08, 2008 5:54 pm    Post subject: Reply with quote

Just goes to show that the best of intentions can be circumvented. I thought that a Naked Quad/Hidden Pair in [r9] qualified as basics. In which case, the UR Type 1 wouldn't have been needed -- my intention.
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daj95376



Joined: 23 Aug 2008
Posts: 3855

PostPosted: Sat Nov 08, 2008 6:17 pm    Post subject: Reply with quote

nataraj wrote:
Is this the series "try it without xy-wing"?

It is/was. Solve it with XY/XYZ-Wing if that works for you. If you want to make it more challenging, then treat it as a No puzzle. All solutions are welcome for my VH series puzzles Exclamation
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cgordon



Joined: 04 May 2007
Posts: 769
Location: ontario, canada

PostPosted: Sat Nov 08, 2008 6:23 pm    Post subject: Reply with quote

Quote:
Just goes to show that the best of intentions can be circumvented. I thought that a Naked Quad/Hidden Pair in [r9] qualified as basics. In which case, the UR Type 1 wouldn't have been needed

For me Naked Quad/Hidden Pairs are usually harder to find than UR's. In the case of UR's, the pairs are clearly visible.
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nataraj



Joined: 03 Aug 2007
Posts: 1029
Location: Vienna, Austria

PostPosted: Sat Nov 08, 2008 6:41 pm    Post subject: Reply with quote

daj95376 wrote:
Just goes to show that the best of intentions can be circumvented. I thought that a Naked Quad/Hidden Pair in [r9] qualified as basics. In which case, the UR Type 1 wouldn't have been needed -- my intention.


needed or not, the UR is still there after the quad , yelling "take ME, take ME!!":

Code:

+--------------------------+--------------------------+--------------------------+
| 1       3       8        | 4       5       9        | 7       2       6        |
| 6       9       2        | 17      8       17       | 34      5       34       |
| 4       7       5        | 3       2       6        | 1       8       9        |
+--------------------------+--------------------------+--------------------------+
| 9       14      14       | 8       67      2        | 356     37      357      |
| 5       8       7        | 16      9       3        | 26      4       12       |
| 3       2       6        | 5       4       17       | 8       9       17       |
+--------------------------+--------------------------+--------------------------+
| 8       16      9        | 267     367     4        | 235     137     2357     |
| 2       5       3        | 79      1       8        | 49      6       47       |
| 7       146     14       | 29      36      5        | 29      13      8        |
+--------------------------+--------------------------+--------------------------+
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Marty R.



Joined: 12 Feb 2006
Posts: 5175
Location: Rochester, NY, USA

PostPosted: Sat Nov 08, 2008 10:29 pm    Post subject: Reply with quote

Code:

+-------+----------+------------+
| 1 3 8 | 4  5  9  | 7   2  6   |
| 6 9 2 | 17 8  17 | 34  5  34  |
| 4 7 5 | 3  2  6  | 1   8  9   |
+-------+----------+------------+
| 9 4 1 | 8  67 2  | 356 37 35  |
| 5 8 7 | 16 9  3  | 26  4  12  |
| 3 2 6 | 5  4  17 | 8   9  17  |
+-------+----------+------------+
| 8 1 9 | 26 67 4  | 235 37 235 |
| 2 5 3 | 79 1  8  | 49  6  47  |
| 7 6 4 | 29 3  5  | 29  1  8   |
+-------+----------+------------+

Play this puzzle online at the Daily Sudoku site

Playing online, I get to the above after basics and the X-wing. I guess the computer sees stuff that I sometimes miss.

Without looking real hard I see two XY-Wings that each remove a candidate from r7c9, solving it for 5 and solving the puzzle.
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