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Puzzle 11/04/11: ~ Difficult

 
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daj95376



Joined: 23 Aug 2008
Posts: 3854

PostPosted: Tue Apr 12, 2011 12:24 am    Post subject: Puzzle 11/04/11: ~ Difficult Reply with quote

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

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: Tue Apr 12, 2011 3:25 am    Post subject: Reply with quote

Code:

(6)r4c2=(6)r3c2-(6=2)r3c1-(2=1)r2c3-(1=6)r2c6-r1c46=(6)r1c7; r4c7<>6
               \                                  /
                 -(6)r1c1

Ted
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storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Tue Apr 12, 2011 4:43 am    Post subject: Reply with quote

tlanglet wrote:
Code:

(6)r4c2=(6)r3c2-(6=2)r3c1-(2=1)r2c3-(1=6)r2c6-r1c46=(6)r1c7; r4c7<>6
               \                                  /
                 -(6)r1c1

Ted


not to nit pick. but this part of your structure

(6=2)r3c1-(2=1)r2c3-(1=6)r2c6

is an xy-chain that adds to your eliminations.
it removes the 6 in r3c6
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peterj



Joined: 26 Mar 2010
Posts: 974
Location: London, UK

PostPosted: Tue Apr 12, 2011 8:12 am    Post subject: Reply with quote

I initially played a skyscraper and then an xy-chain, but also found this one-stepper making the same elimination as Ted's ..
Code:
(6=5)r1c7 - r3c8=(5-7)r3c6=r3c2 - (7=6)r4c2 ; r4c7<>6
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tlanglet



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

PostPosted: Tue Apr 12, 2011 12:14 pm    Post subject: Reply with quote

storm_norm wrote:
tlanglet wrote:
Code:

(6)r4c2=(6)r3c2-(6=2)r3c1-(2=1)r2c3-(1=6)r2c6-r1c46=(6)r1c7; r4c7<>6
               \                                  /
                 -(6)r1c1

Ted


not to nit pick. but this part of your structure

(6=2)r3c1-(2=1)r2c3-(1=6)r2c6

is an xy-chain that adds to your eliminations.
it removes the 6 in r3c6

Norm, Thanks for the comment. Actually, I initially spotted the xy-wing and while checking for additional deletions by transporting the pincers, I noted the full step. However, I was not sure how to notate the xy-wing deletion so I left it out.

Ted
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daj95376



Joined: 23 Aug 2008
Posts: 3854

PostPosted: Tue Apr 12, 2011 1:21 pm    Post subject: Reply with quote

tlanglet wrote:
Norm, Thanks for the comment. Actually, I initially spotted the xy-wing and while checking for additional deletions by transporting the pincers, I noted the full step. However, I was not sure how to notate the xy-wing deletion so I left it out.

Suggestion:

...; r4c6<>6, r3c6<>6 (internal XY-Wing)
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tlanglet



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

PostPosted: Tue Apr 12, 2011 1:35 pm    Post subject: Reply with quote

daj95376 wrote:
tlanglet wrote:
Norm, Thanks for the comment. Actually, I initially spotted the xy-wing and while checking for additional deletions by transporting the pincers, I noted the full step. However, I was not sure how to notate the xy-wing deletion so I left it out.

Suggestion:

...; r4c6<>6, r3c6<>6 (internal XY-Wing)

Danny, very nice suggestion.

Ted
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Asellus



Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA

PostPosted: Tue Apr 12, 2011 6:48 pm    Post subject: Reply with quote

It can be boiled down rather elegantly to:
XYWing[(6)r2c6=(6)r3c1] - Skyscraper[(6)r3c2=(6)r1c7]; r1c146|r2c8|r3c68<>6
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Marty R.



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

PostPosted: Wed Apr 13, 2011 1:00 am    Post subject: Reply with quote

Skyscraper; r1c1, r3c8<>6
XY-Wing (126), flightless with transport of each pincer; r4c7<>6
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