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Puzzle 10/10/31: A16 Advanced

 
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daj95376



Joined: 23 Aug 2008
Posts: 3854
PostPosted: Sat Oct 30, 2010 5:32 pm    Post subject: Puzzle 10/10/31: A16 Advanced Reply with quote
I'm hanging up my hat on posting puzzles. Today's puzzles are the last.

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

Play this puzzle online at the Daily Sudoku site
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peterj



Joined: 26 Mar 2010
Posts: 974
Location: London, UK
PostPosted: Wed Nov 03, 2010 9:05 am    Post subject: Reply with quote
I struggled with this - the first time through I couldn't find an Advanced-only solution, second time I saw it - well hidden from me anyway!
Quote:
xyz-wing(12-3) r4c5 ; r6c5<>3
finned x-wing(3) c5, c7 ; r8c46<>3
finned x-wing(6) r4, c8 ; r3c6<>6
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daj95376



Joined: 23 Aug 2008
Posts: 3854
PostPosted: Wed Nov 03, 2010 2:59 pm    Post subject: Reply with quote
Peter: Moves present after basics.

Code:
 +-----------------------------------------------------------------------+
 |  5      4      2      |  136    8      136    |  16     9      7      |
 |  1      8      6      |  2      9      7      |  5      4      3      |
 |  9      7      3      |  146    145    156    |  2      16     8      |
 |-----------------------+-----------------------+-----------------------|
 |  4      5      18     |  9      123    12368  |  136    7      26     |
 |  3      2      189    |  168    7      1568   |  4      156    569    |
 |  7      6      19     |  13     1235   4      |  8      135    259    |
 |-----------------------+-----------------------+-----------------------|
 |  8      3      4      |  5      6      9      |  7      2      1      |
 |  2      9      57     |  1347   134    13     |  36     8      56     |
 |  6      1      57     |  378    23     238    |  9      35     4      |
 +-----------------------------------------------------------------------+
 # 58 eliminations remain

 <36+1>  XY-Wing  r8c7/r1c7+r8c6         <> 1    r1c6   -or-

 <12+3>  XYZ-Wing r4c5/r6c4+r9c5         <> 3    r6c5   -or-

 c48\r35 finned  X-Wing                  <> 6    r3c6   -or-
   c8b5  Empty Rectangle                 <> 6    r3c6   -or-
 r4c8    2-String Kite   (grouped)       <> 6    r3c6

Code:
===== ===== ===== ===== Ratings are Accumulative in Techniques ===== ===== =====

Basics:    Naked/Hidden Single/Pair/Triple/Quad, Locked Candidates 1/2

VH:        BUG+1, Remote Pair, UR Type 1, X-Wing, XY-Wing

Advanced:  2-String Kite, Skyscraper, Empty Rectangle, finned/Sashimi X-Wing,
           XYZ-Wing, UR Type 2/4

XY:        M/W/S/L-Wing, XY-Chain, BUG+2, BUG+3, other URs

Extreme:   Chain, Loop, SIN (Single Inference Network)
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peterj



Joined: 26 Mar 2010
Posts: 974
Location: London, UK
PostPosted: Wed Nov 03, 2010 6:57 pm    Post subject: Reply with quote
Danny, thanks, for some reason I had a blind spot on the finned-xw(6)... first time I ended up using a short chain...
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Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
PostPosted: Wed Nov 03, 2010 8:43 pm    Post subject: Reply with quote
I saw the Finned 6 but didn't play it because I didn't think it would do much. So I used one of my typical too-many-moves solutions.

XY-Wing (361)
XY-Chain
W-Wing (13) + transport
W-Wing (13), different cells
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keith



Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
PostPosted: Mon Nov 22, 2010 5:51 am    Post subject: Reply with quote
Joined: 21 Nov 2010
Posts: 1

[moved by keith to correct thread]

Originally posted by Lorne. Posted: Sun Nov 21, 2010 8:24 pm Post subject: Puzzle 10/10/31: A16 Advanced


Hi all,

For the final solution R1C3 is 2 and R1C4 is 6. R2C3 is 6 and R2C4 is 2. My question concerns R1C4. I did not originally place a 6 there because it creates a uniqueness issue where the final puzzle does not have a unique solution. However, that is the only way to solve the puzzle. Maybe I am missing something basic, but why is there no issue with R1C4 being a value of 6?

Thnx for any help you can provide,

Lorne
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peterj



Joined: 26 Mar 2010
Posts: 974
Location: London, UK
PostPosted: Mon Nov 22, 2010 7:45 am    Post subject: Reply with quote
Lorne, the reason is beacuse r1c3, r1c4 and r2c3 are all "givens" i.e original clues. If these solution had been derived while solving the puzzle then you are right that you would not be able to place a 6 in r1c4. But because the puzzle setter has specified one (or more) of the corners of the rectangle as a given there is no ambiguity and only a single solution.
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lorne



Joined: 22 Nov 2010
Posts: 5
PostPosted: Mon Nov 22, 2010 4:16 pm    Post subject: Thanks Reply with quote
Thanks Peter - makes sense.

Lorne
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