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Feb 6 DB

 
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Earl



Joined: 30 May 2007
Posts: 677
Location: Victoria, KS

PostPosted: Sun Feb 07, 2010 4:06 pm    Post subject: Feb 6 DB Reply with quote

The Feb 6 DB is, pradoxically, an easy tall order.

A Solution: skyscraper in 5

Earl


Code:

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

Play this puzzle online at the Daily Sudoku site
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arkietech



Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA

PostPosted: Sun Feb 07, 2010 7:52 pm    Post subject: Reply with quote

A different one stepper:
Quote:
remote pair 58
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Louise56



Joined: 21 Sep 2005
Posts: 94
Location: El Cajon, California USA

PostPosted: Mon Feb 08, 2010 12:23 am    Post subject: Reply with quote

I can see the skyscraper but I don't understand the remote pair 58. I have lots of 58s but I'm not sure what to do with them. Confused
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arkietech



Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA

PostPosted: Mon Feb 08, 2010 1:32 am    Post subject: Reply with quote

Louise56 wrote:
I can see the skyscraper but I don't understand the remote pair 58. I have lots of 58s but I'm not sure what to do with them. Confused


Code:
 *--------------------------------------------------*
 | 9    3    248  | 5    6    78   | 48   1    27   |
 | 7   *58   24   | 49   1    3    | 6   *58   29   |
 | 6    1    458  | 48   79   2    | 458  3    79   |
 |----------------+----------------+----------------|
 | 4    6    3    | 7    8    1    | 9    2    5    |
 | 5    2    9    | 6    3    4    | 1    7    8    |
 | 8    7    1    | 2    5    9    | 3    4    6    |
 |----------------+----------------+----------------|
 | 1   *58   6    | 3    279  578  | 27   589  4    |
 | 2    9    7    | 1    4    58   | 58   6    3    |
 | 3    4   *58   | 89   27   6    | 27   9-58 1    |
 *--------------------------------------------------*
remote pair 58
if r9c3 is 8 then r2c8 is 5
if r9c3 is 5 then r2c8 is 8
so r9c8 <> 5 or 8
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Louise56



Joined: 21 Sep 2005
Posts: 94
Location: El Cajon, California USA

PostPosted: Mon Feb 08, 2010 2:13 am    Post subject: Reply with quote

Thank-you, that does make sense. Now when you see a lot of 58s for example, how do you know which one will be your pivot (not sure what the term is, but how would I know which 58 pair to use the logic on?)
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arkietech



Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA

PostPosted: Mon Feb 08, 2010 3:03 am    Post subject: Reply with quote

Louise56 wrote:
Thank-you, that does make sense. Now when you see a lot of 58s for example, how do you know which one will be your pivot (not sure what the term is, but how would I know which 58 pair to use the logic on?)

You have to have 5 58's so one box has to have 2. Anyway that is what I look for. Four of them have to contain two candidates ( 58 ) the 5th (the target) has 58 plus other candidates. The 58 may be removed from the target.

Hope this helps.
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keith



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

PostPosted: Mon Feb 08, 2010 3:39 am    Post subject: Reply with quote

Louise56 wrote:
Thank-you, that does make sense. Now when you see a lot of 58s for example, how do you know which one will be your pivot (not sure what the term is, but how would I know which 58 pair to use the logic on?)

http://www.dailysudoku.com/sudoku/forums/viewtopic.php?t=2143

Keith
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Marty R.



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

PostPosted: Mon Feb 08, 2010 4:59 am    Post subject: Reply with quote

Louise56 wrote:
Thank-you, that does make sense. Now when you see a lot of 58s for example, how do you know which one will be your pivot (not sure what the term is, but how would I know which 58 pair to use the logic on?)

To an extent, I view it as trial and error. You see which of the pairs you can make a chain with. The chain itself needs to be an even number of cells.

I have to disagree with a statement that was made about the "target" cell having to contain a 58. Any cell that sees both ends of the chain can have a 5 and/or 8 removed. If it has both, all the better, but it only needs one or the other for an elimination to be made.
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arkietech



Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA

PostPosted: Mon Feb 08, 2010 8:27 am    Post subject: Reply with quote

Marty R. wrote:
Louise56 wrote:
Thank-you, that does make sense. Now when you see a lot of 58s for example, how do you know which one will be your pivot (not sure what the term is, but how would I know which 58 pair to use the logic on?)

To an extent, I view it as trial and error. You see which of the pairs you can make a chain with. The chain itself needs to be an even number of cells.

I have to disagree with a statement that was made about the "target" cell having to contain a 58. Any cell that sees both ends of the chain can have a 5 and/or 8 removed. If it has both, all the better, but it only needs one or the other for an elimination to be made.

Wouldn't this be a remote single rather than a remote pair? Very Happy

Who dat did it!
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Kdelle



Joined: 20 Mar 2008
Posts: 59
Location: Hudson, NH

PostPosted: Mon Feb 08, 2010 3:26 pm    Post subject: Reply with quote

arkietech wrote:
Louise56 wrote:
I can see the skyscraper but I don't understand the remote pair 58. I have lots of 58s but I'm not sure what to do with them. Confused


Code:
 *--------------------------------------------------*
 | 9    3    248  | 5    6    78   | 48   1    27   |
 | 7   *58   24   | 49   1    3    | 6   *58   29   |
 | 6    1    458  | 48   79   2    | 458  3    79   |
 |----------------+----------------+----------------|
 | 4    6    3    | 7    8    1    | 9    2    5    |
 | 5    2    9    | 6    3    4    | 1    7    8    |
 | 8    7    1    | 2    5    9    | 3    4    6    |
 |----------------+----------------+----------------|
 | 1   *58   6    | 3    279  578  | 27   589  4    |
 | 2    9    7    | 1    4    58   | 58   6    3    |
 | 3    4   *58   | 89   27   6    | 27   9-58 1    |
 *--------------------------------------------------*
remote pair 58
if r9c3 is 8 then r2c8 is 5
if r9c3 is 5 then r2c8 is 8
so r9c8 <> 5 or 8



Dan, is this also considered a kite?

Thanks,

Kathy
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arkietech



Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA

PostPosted: Mon Feb 08, 2010 6:14 pm    Post subject: Reply with quote

Kdelle wrote:
Dan, is this also considered a kite?

No. There are many skyscrapers on 5 -- look in columns 3 and 7 for one and
in rows 3 and 9 for another.

I don't see any on 8's.
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Louise56



Joined: 21 Sep 2005
Posts: 94
Location: El Cajon, California USA

PostPosted: Mon Feb 08, 2010 7:14 pm    Post subject: Reply with quote

Very helpful replies...thank-you Very Happy
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Asellus



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

PostPosted: Sat Feb 13, 2010 8:06 am    Post subject: Reply with quote

Just to help (I hope) avoid confusion...

The eliminations in this puzzle CAN also be seen as BOTH a <5> Kite/Turbot Fish AND an <8> Kite/Turbot Fish that happen to occupy the same cells (in r2-c2-b7). But, most would would see it as the "more compact" special case it is, a Remote Naked Pair. As far as I can see, any 4-identical-cell RNP can also be seen as two superimposed Kites/Turbot Fish/Skyscrapers.
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arkietech



Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA

PostPosted: Sat Feb 13, 2010 8:34 am    Post subject: Reply with quote

Asellus wrote:
Just to help (I hope) avoid confusion...

The eliminations in this puzzle CAN also be seen as BOTH a <5> Kite/Turbot Fish AND an <8> Kite/Turbot Fish that happen to occupy the same cells (in r2-c2-b7). But, most would would see it as the "more compact" special case it is, a Remote Naked Pair. As far as I can see, any 4-identical-cell RNP can also be seen as two superimposed Kites/Turbot Fish/Skyscrapers.

Thanks Asellus. I stand corrected. I could not see the trees for the forest. Very Happy
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