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Moderate: Set C Puzzle 27

 
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daj95376



Joined: 23 Aug 2008
Posts: 3855

PostPosted: Mon Nov 24, 2008 4:27 pm    Post subject: Moderate: Set C Puzzle 27 Reply with quote

nataraj formatting tool. All rights reserved.

Code:

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

Play online

For those who are tired of wings and would like something more reasonable.
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keith



Joined: 19 Sep 2005
Posts: 3150
Location: near Detroit, Michigan, USA

PostPosted: Mon Nov 24, 2008 9:34 pm    Post subject: Reply with quote

Cool! A triple that extends into an XY-wing. Laughing

Keith
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arkietech



Joined: 31 Jul 2008
Posts: 1709
Location: Northwest Arkansas USA

PostPosted: Mon Nov 24, 2008 9:56 pm    Post subject: Reply with quote

did not see any triple xy magic. Did find a UR that did it for me.
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keith



Joined: 19 Sep 2005
Posts: 3150
Location: near Detroit, Michigan, USA

PostPosted: Mon Nov 24, 2008 10:58 pm    Post subject: Reply with quote

arkietech wrote:
did not see any triple xy magic. Did find a UR that did it for me.

There are two UR's <18> and <19>. They both solve it, the first is more direct. The first UR was there long before I finished basics, so this could be a short puzzle.

If you eschew Razz the UR's, there is this. After basics:
Code:
+-------------+-------------+-------------+
| 4   2   6   | 7   3   5   | 1   9   8   |
| 9   18  18  | 24  24  6   | 5   3   7   |
| 7   3   5   | 19  19  8   | 4   6   2   |
+-------------+-------------+-------------+
| 268 5   7   | 234 248 9   | 238 1   46  |
| 1   4   238 | 23  6   7   | 9   28  5   |
| 268 9   238 | 5   248 1   | 238 7   46  |
+-------------+-------------+-------------+
| 5   7   4   | 189 19  23  | 6   28  13  |
| 28  6   9   | 18  5   23  | 7   4   13  |
| 3   18  128 | 6   7   4   | 28  5   9   |
+-------------+-------------+-------------+

The three <28> cells in silo three are your friends!

1. Skyscraper takes out <8> in R9C3.

2. Now, we have a triple <28> <18> <12> in R9. Extending <28>, it takes out <2> in R5C3!

3. Then, there is the <18> in C3. It makes an extended XY-wing <18> <12> <28> that takes out <8> in our victim, R6C3.

And, the puzzle is history. Much fun! Very Happy

Danny,

Where you thinking of the UR when you posted the puzzle? Or, maybe, these short chains? How do you rank UR's and other uniqueness techniques in terms of difficulty?

Keith
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Marty R.



Joined: 12 Feb 2006
Posts: 5123
Location: Rochester, NY, USA

PostPosted: Tue Nov 25, 2008 12:30 am    Post subject: Reply with quote

Quote:
Code:
+-------------+-------------+-------------+
| 4   2   6   | 7   3   5   | 1   9   8   |
| 9   18  18  | 24  24  6   | 5   3   7   |
| 7   3   5   | 19  19  8   | 4   6   2   |
+-------------+-------------+-------------+
| 268 5   7   | 234 248 9   | 238 1   46  |
| 1   4   238 | 23  6   7   | 9   28  5   |
| 268 9   238 | 5   248 1   | 238 7   46  |
+-------------+-------------+-------------+
| 5   7   4   | 189 19  23  | 6   28  13  |
| 28  6   9   | 18  5   23  | 7   4   13  |
| 3   18  128 | 6   7   4   | 28  5   9   |
+-------------+-------------+-------------+


The three <28> cells in silo three are your friends!

1. Skyscraper takes out <8> in R9C3.


I give up. Where is it?
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daj95376



Joined: 23 Aug 2008
Posts: 3855

PostPosted: Tue Nov 25, 2008 12:46 am    Post subject: Reply with quote

keith wrote:
Danny,

Where you thinking of the UR when you posted the puzzle? Or, maybe, these short chains? How do you rank UR's and other uniqueness techniques in terms of difficulty?

Keith

I would probably rank UR Type 1 as moderate and other URs as hard or above ... depending on the complexity of the eliminations.

For this puzzle, I just noticed that it could be solved with colors ... and failed to check the techniques necessary to get the same results. Embarassed

Code:
         Colors                          <> 2    [r5c3]
         Colors                          <> 8    [r46c1],[r9c3]

Code:
 2-String Kite => [r5c3]<>2   present but not necessary
 *--------------------------------------------------*
 | 4    2    6    | 7    3    5    | 1    9    8    |
 | 9    18   18   | 24   24   6    | 5    3    7    |
 | 7    3    5    | 19   19   8    | 4    6    2    |
 |----------------+----------------+----------------|
 | 268  5    7    | 234  248  9    | 238  1    46   |
 | 1    4    38-2 | 23   6    7    | 9   *28   5    |
 | 268  9    238  | 5    248  1    | 238  7    46   |
 |----------------+----------------+----------------|
 | 5    7    4    | 189  19   23   | 6   *28   13   |
 | 28   6    9    | 18   5    23   | 7    4    13   |
 | 3    18  *128  | 6    7    4    |*28   5    9    |
 *--------------------------------------------------*

Code:
 X-Chain for (8) => [r46c1]<>8
 *--------------------------------------------------*
 | 4    2    6    | 7    3    5    | 1    9    8    |
 | 9    18   18   | 24   24   6    | 5    3    7    |
 | 7    3    5    | 19   19   8    | 4    6    2    |
 |----------------+----------------+----------------|
 | 26-8 5    7    | 234  248  9    | 238  1    46   |
 | 1    4   a238  | 23   6    7    | 9   b28   5    |
 | 26-8 9    238  | 5    248  1    | 238  7    46   |
 |----------------+----------------+----------------|
 | 5    7    4    |d189  19   23   | 6   c28   13   |
 |f28   6    9    |e18   5    23   | 7    4    13   |
 | 3    18   12-8 | 6    7    4    | 28   5    9    |
 *--------------------------------------------------*
 Siamese Sashimi Swordfish

FWIW: I knew the URs were there, but I hadn't planned on using them in the solution or in ranking the puzzle.


Last edited by daj95376 on Tue Nov 25, 2008 7:47 am; edited 4 times in total
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keith



Joined: 19 Sep 2005
Posts: 3150
Location: near Detroit, Michigan, USA

PostPosted: Tue Nov 25, 2008 12:46 am    Post subject: Reply with quote

Marty R. wrote:
Quote:
Code:
+-------------+-------------+-------------+
| 4   2   6   | 7   3   5   | 1   9   8   |
| 9   18  18  | 24  24  6   | 5   3   7   |
| 7   3   5   | 19  19  8   | 4   6   2   |
+-------------+-------------+-------------+
| 268 5   7   | 234 248 9   | 238 1   46  |
| 1   4   238D| 23  6   7   | 9   28C 5   |
| 268 9   238 | 5   248 1   | 238 7   46  |
+-------------+-------------+-------------+
| 5   7   4   | 189 19  23  | 6   28B 13  |
| 28  6   9   | 18  5   23  | 7   4   13  |
| 3   18 12-8 | 6   7   4   | 28A 5   9   |
+-------------+-------------+-------------+


The three <28> cells in silo three are your friends!

1. Skyscraper takes out <8> in R9C3.


I give up. Where is it?


Coloring on <8> ABCD eliminates <8> from R9C3. Or, some would say, a skyscraper or kite BA and CD.

Keith
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Marty R.



Joined: 12 Feb 2006
Posts: 5123
Location: Rochester, NY, USA

PostPosted: Tue Nov 25, 2008 1:29 am    Post subject: Reply with quote

Quote:
Coloring on <8> ABCD eliminates <8> from R9C3. Or, some would say, a skyscraper or kite BA and CD.

Just a terminology issue. I still think of a skyscraper narrowly as parallel strong links, the way I originally learned it.
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re'born



Joined: 28 Oct 2007
Posts: 80

PostPosted: Tue Nov 25, 2008 3:55 am    Post subject: Reply with quote

If you forgo the pleasant UR, the same cells point to a Kraken x-wing that eliminates 8 from r5c3, solving the puzzle. I'm really starting to enjoy finding those.

Incidentally, this same elimination can be seen as a transported xyz-wing with pivot r9c3 and pincers r8c1, r2c3. Transport r8c1<8> to r5c8<8> to get the elimination.
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daj95376



Joined: 23 Aug 2008
Posts: 3855

PostPosted: Tue Nov 25, 2008 7:57 am    Post subject: Reply with quote

re'born wrote:
If you forgo the pleasant (18) UR, the same cells point to a Kraken x-wing that eliminates 8 from r5c3, solving the puzzle. I'm really starting to enjoy finding those.

Very good. Now, how about the column Kraken X-Wing => [r46c1],[r8c4],[r9c23]<>8 ?

I call the eliminations in [r8c4],[r9c23] indirect eliminations.
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re'born



Joined: 28 Oct 2007
Posts: 80

PostPosted: Tue Nov 25, 2008 2:00 pm    Post subject: Reply with quote

daj95376 wrote:
re'born wrote:
If you forgo the pleasant (1Cool UR, the same cells point to a Kraken x-wing that eliminates 8 from r5c3, solving the puzzle. I'm really starting to enjoy finding those.

Very good. Now, how about the column Kraken X-Wing => [r46c1],[r8c4],[r9c23]<>8 ?

I call the eliminations in [r8c4],[r9c23] indirect eliminations.


So in this case once you make the eliminations r46c1<>8, the indirect eliminations follow, but I suspect this is particular to this situation. What is the general idea of an indirect elimination? Also, there is another column Kraken X-wing on 8 which gives r46c7<>8.
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daj95376



Joined: 23 Aug 2008
Posts: 3855

PostPosted: Tue Nov 25, 2008 4:43 pm    Post subject: Reply with quote

re'born wrote:
What is the general idea of an indirect elimination?

Indirect eliminations based on the exterior fin cell is fundamental to a Kraken fish. However, I must admit that I (probably) originated the concept of including indirect eliminations based on the fish as well.

Originally, when trying to understand a posted Kraken fish, I would run my solver's Templates logic against the grid to let me know where every single-digit elimination existed for a candidate. Then, I would compare the results to the marked PM included with the Kraken fish.

I noticed that the fish pattern often stranded a Hidden Single and/or a Locked Candidate that caused additional eliminations to overlay with those from the external fin cell. This often accounted for all single-digit eliminations present for that candidate. So, I decided to include all related single-digit eliminations into my Kraken fish.

Eventually, Kraken fish just started appearing in grids without needing my solver. I only claim to catch a very small fraction of those present!
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