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Puzzle NR_008

 
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daj95376



Joined: 23 Aug 2008
Posts: 3854

PostPosted: Mon May 04, 2009 9:33 am    Post subject: Puzzle NR_008 Reply with quote

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

Play this puzzle online at the Daily Sudoku site
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tlanglet



Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills

PostPosted: Mon May 04, 2009 2:11 pm    Post subject: Reply with quote

I ignored the three obvious URs, and solved the puzzle with:
Quote:
a xy-wing 457 with pivot 47 at r9c5,
a kite on 5 with hinge in box3,
and another xy-wing 123 with pivot 13 in r9c2

Ted
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keith



Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA

PostPosted: Tue May 05, 2009 12:12 am    Post subject: Reply with quote

Ignoring the UR:

Two XY-wings, a skyscraper on 2, another XY-wing.

Keith
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Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA

PostPosted: Fri May 08, 2009 1:10 am    Post subject: Reply with quote

I used Ted's three moves but that was after I used the two Type 1 URs.
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tlanglet



Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills

PostPosted: Fri May 08, 2009 1:39 am    Post subject: Reply with quote

Marty R. wrote:
I used Ted's three moves but that was after I used the two Type 1 URs.

I am always amazed at what moves are critical/useful. When working on this puzzle, I assumed that the two URs would be useful, but apparently not!

Ted
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gindaani



Joined: 06 Mar 2009
Posts: 79

PostPosted: Fri May 08, 2009 10:42 pm    Post subject: Reply with quote

tlanglet wrote:
I ignored the three obvious URs, and solved the puzzle with:
Quote:
a xy-wing 457 with pivot 47 at r9c5,
a kite on 5 with hinge in box3,
and another xy-wing 123 with pivot 13 in r9c2

Ted

keith wrote:
Ignoring the UR:

Two XY-wings, a skyscraper on 2, another XY-wing.

Keith

I must have missed something in the basics. After the basics, the only move I see is the 475 xy-wing with pivot r9c5. After the xy-wing, I have:

Code:

+-------------+-------------+-------------+
| 8  9    35  | 1  47 47    | 235 25 6    |
| 17 15   6   | 8  3  2     | 57  9  4    |
| 27 23   4   | 6  5  9     | 37  1  8    |
+-------------+-------------+-------------+
| 5  6    1   | 3  2  8     | 4   7  9    |
| 4  8    9   | 57 1  57    | 6   3  2    |
| 3  7    2   | 4  9  6     | 15  8  15   |
+-------------+-------------+-------------+
| 9  1235 357 | 57 6  13457 | 8   24 137  |
| 12 4    357 | 9  8  1357  | 125 6  1357 |
| 6  135  8   | 2  47 1347  | 9   45 1357 |
+-------------+-------------+-------------+

Play this puzzle online at the Daily Sudoku site

I don't see the kite with hinge in box 3 (the <5> in r1c7 prevents the kite). I also do not see another xy-wing. I see skyscrapers on 2, but they don't make any eliminations.

What am I missing?

I can eliminate the 5 from r1c7 using advanced coloring, but I don't see any easy way to remove it. After the AC, I still don't see another xy-wing, but the kite is there (and the 132 xy-wing finishes it off).

My solution then:

475 xy-wing
Advanced Coloring [ (5=3)r1c3 - (3=2)r3c2 - (2)r7c2 = (2)r7c8 - (2=5)r1c8 ]
kite on 5
132 xy-wing
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tlanglet



Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills

PostPosted: Sat May 09, 2009 12:13 am    Post subject: Reply with quote

gindaani wrote:
tlanglet wrote:
I ignored the three obvious URs, and solved the puzzle with:
Quote:
a xy-wing 457 with pivot 47 at r9c5,
a kite on 5 with hinge in box3,
and another xy-wing 123 with pivot 13 in r9c2

Ted


I must have missed something in the basics. After the basics, the only move I see is the 475 xy-wing with pivot r9c5. After the xy-wing, I have:

Code:

+-------------+-------------+-------------+
| 8  9    35  | 1  47 47    | 235 25 6    |
| 17 15   6   | 8  3  2     | 57  9  4    |
| 27 23   4   | 6  5  9     | 37  1  8    |
+-------------+-------------+-------------+
| 5  6    1   | 3  2  8     | 4   7  9    |
| 4  8    9   | 57 1  57    | 6   3  2    |
| 3  7    2   | 4  9  6     | 15  8  15   |
+-------------+-------------+-------------+
| 9  1235 357 | 57 6  13457 | 8   24 137  |
| 12 4    357 | 9  8  1357  | 125 6  1357 |
| 6  135  8   | 2  47 1347  | 9   45 1357 |
+-------------+-------------+-------------+

Play this puzzle online at the Daily Sudoku site

I don't see the kite with hinge in box 3 (the <5> in r1c7 prevents the kite).

The <5> in r1c7 does not prevent the kite. If r1c7=5 then both pincers r2c2 and r9c8 must be true and the 5 in r9c2 is deleted. If a 5 exists in the intersection cell of the two strong links forming the kite, which is this case would be cell r2c8, then the kite is destroyed.


Ted
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gindaani



Joined: 06 Mar 2009
Posts: 79

PostPosted: Sat May 09, 2009 1:02 am    Post subject: Reply with quote

tlanglet wrote:
The <5> in r1c7 does not prevent the kite. If r1c7=5 then both pincers r2c2 and r9c8 must be true and the 5 in r9c2 is deleted. If a 5 exists in the intersection cell of the two strong links forming the kite, which is this case would be cell r2c8, then the kite is destroyed.

I see it now. It would prevent the kite in the other direction, not the one that eliminates 5 in r9c2.

Thanks! I knew I was missing something.
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