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wapati
Joined: 10 Jun 2008
Posts: 472
Location: Brampton, Ontario, Canada.
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 Posted: Wed Jul 01, 2009 1:50 am Post subject: Swordfish, sashimi I think. |
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This puzzle has a lot of twists, at least when I try it.
| Code: | 7 4 .|. 6 .|. . .
. 5 .|3 . .|. 4 .
8 . .|. . .|. 1 .
-----+-----+-----
. 2 1|. . 4|5 7 .
5 . .|. . .|. . 1
. 7 4|1 . .|6 9 .
-----+-----+-----
. 3 .|. . .|. . 4
. 1 .|. . 2|. 6 .
. . .|. 5 .|. 8 2 |
I can solve it by bashing away and using several URs.
I came to a position that has a useless xy-wing and saw something that works but I think it is a quirk of this puzzle.
This isn't exactly where I was but the trick works here.
| Code: | .------------------.------------------.------------------.
| 7 4 29 |*25 6 1 | 8 3 *59 |
| 1 5 269 | 3 79 8 |*29 4 679 |
| 8 6-9 3 | 25 4 79 | 279 1 567 |
:------------------+------------------+------------------:
| 69 2 1 | 689 89 4 | 5 7 3 |
| 5 8 69 | 679 3 679 | 4 2 1 |
| 3 7 4 | 1 2 5 | 6 9 8 |
:------------------+------------------+------------------:
| 2 3 8 | 679 1 679 | 79 5 4 |
| 49 1 5 | 4789 789 2 | 3 6 79 |
| 469 69 7 | 49 5 3 | 1 8 2 |
'------------------'------------------'------------------' |
There are a couple of odd URs here that progress but look at the xy-wing.
Whichever end has a 2 sets r3c2 to 6, one pretty directly and the other because of the created 79 pair in r3.
Is this a chain, an accident or something intersting? |
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Wed Jul 01, 2009 11:35 am Post subject: Re: Swordfish, sashimi I think. |
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| wapati wrote: | This isn't exactly where I was but the trick works here.
| Code: | .------------------.------------------.------------------.
| 7 4 29 |*25 6 1 | 8 3 *59 |
| 1 5 269 | 3 79 8 |*29 4 679 |
| 8 6-9 3 | 25 4 79 | 279 1 567 |
:------------------+------------------+------------------:
| 69 2 1 | 689 89 4 | 5 7 3 |
| 5 8 69 | 679 3 679 | 4 2 1 |
| 3 7 4 | 1 2 5 | 6 9 8 |
:------------------+------------------+------------------:
| 2 3 8 | 679 1 679 | 79 5 4 |
| 49 1 5 | 4789 789 2 | 3 6 79 |
| 469 69 7 | 49 5 3 | 1 8 2 |
'------------------'------------------'------------------' |
There are a couple of odd URs here that progress but look at the xy-wing.
Whichever end has a 2 sets r3c2 to 6, one pretty directly and the other because of the created 79 pair in r3.
Is this a chain, an accident or something intersting? |
Chain: (my notation may not match others)
(9=2)r1c3 - ... - (2)r3c7 = (79)r3c67 => [r3c2]<>9 |
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tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
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| Posted: Wed Jul 01, 2009 5:37 pm Post subject: Re: Swordfish, sashimi I think. |
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| daj95376 wrote: | | wapati wrote: | This isn't exactly where I was but the trick works here.
| Code: | .------------------.------------------.------------------.
| 7 4 29 |*25 6 1 | 8 3 *59 |
| 1 5 269 | 3 79 8 |*29 4 679 |
| 8 6-9 3 | 25 4 79 | 279 1 567 |
:------------------+------------------+------------------:
| 69 2 1 | 689 89 4 | 5 7 3 |
| 5 8 69 | 679 3 679 | 4 2 1 |
| 3 7 4 | 1 2 5 | 6 9 8 |
:------------------+------------------+------------------:
| 2 3 8 | 679 1 679 | 79 5 4 |
| 49 1 5 | 4789 789 2 | 3 6 79 |
| 469 69 7 | 49 5 3 | 1 8 2 |
'------------------'------------------'------------------' |
There are a couple of odd URs here that progress but look at the xy-wing.
Whichever end has a 2 sets r3c2 to 6, one pretty directly and the other because of the created 79 pair in r3.
Is this a chain, an accident or something intersting? |
Chain: (my notation may not match others)
(9=2)r1c3 - ... - (2)r3c7 = (79)r3c67 => [r3c2]<>9 |
I believe that this is also another example of the "Hidden Pair" approach Norm has successfully used several times recently.
Ted |
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storm_norm
Joined: 18 Oct 2007
Posts: 1741
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| Posted: Thu Jul 02, 2009 9:12 pm Post subject: |
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| Quote: | I believe that this is also another example of the "Hidden Pair" approach Norm has successfully used several times recently.
Ted |
the weak inference in the chain that the {7,9} pair has to the 9 in r3c3 in Danny's example is, to my eyes, akin to a naked pair.
I wouldn't call it a use of a hidden pair where the weak inference is between the hidden pair and a candidate within the cells containing the hidden pair.
this reminds me of a discussion on the player's forum about this same topic. |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Thu Jul 02, 2009 9:38 pm Post subject: |
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My solution is not very esoteric. After basics: | Code: | +----------------+----------------+----------------+
| 7 4 29 | 25 6 1 | 8 3 59 |
| 1 5 269 | 3 79 8 | 279 4 679 |
| 8 69a 3 | 25 4 79 | 279 1 5679 |
+----------------+----------------+----------------+
| 69 2 1 | 689 89 4 | 5 7 3 |
| 5 8 69 | 679 3 679 | 4 2 1 |
| 3 7 4 | 1 2 5 | 6 9 8 |
+----------------+----------------+----------------+
| 2 3 8 | 679 1 679 | 79 5 4 |
| 49@ 1 5 | 4789 789 2 | 3 6 79 |
| 469 69 7 | 49@ 5 3 | 1 8 2 |
+----------------+----------------+----------------+ |
There is a Type 6 UR, the cells marked @ must be <4>. Leading to: | Code: | +----------------+----------------+----------------+
| 7 4 29 | 25 6 1 | 8 3 59 |
| 1 5 269 | 3 79B 8 | 279 4 679 |
| 8 69a 3 | 25 4 79b | 279 1 5679 |
+----------------+----------------+----------------+
| 69A 2 1 | 689 8-9 4 | 5 7 3 |
| 5 8 69 | 679 3 679 | 4 2 1 |
| 3 7 4 | 1 2 5 | 6 9 8 |
+----------------+----------------+----------------+
| 2 3 8 | 679 1 679 | 79 5 4 |
| 4 1 5 | 789 789 2 | 3 6 79 |
| 69a 69A 7 | 4 5 3 | 1 8 2 |
+----------------+----------------+----------------+ |
Start multicoloring (a skyscraper) at a and b in R3. Any cell that sees A and B cannot be <9>. That leaves two remote pair eliminations of <79> in B3, solving the puzzle.
Keith  |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Fri Jul 03, 2009 12:44 am Post subject: |
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| Quote: | Whichever end has a 2 sets r3c2 to 6, one pretty directly and the other because of the created 79 pair in r3.
Is this a chain, an accident or something interesting? |
Wapati,
This is the kind of thing that re'born used to do all the time. A few years ago it seemed (to me) to be very esoteric, now I think it is just very good problem solving.
It is not a chain, and it is not an accident. It is an instance of very good insight!
Best wishes,
Keith |
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