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nataraj
Joined: 03 Aug 2007
Posts: 1048
Location: near Vienna, Austria
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 Posted: Tue Jul 22, 2008 1:46 pm Post subject: Times "super fiendish" May 2, 2008 |
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From "The Times":
| Code: |
+-----------+-----------+-----------+
| . 4 3 | . . . | . . . |
| . 8 . | 3 . 7 | . 6 2 |
| . . . | . 8 . | . . 1 |
+-----------+-----------+-----------+
| . 9 . | 5 . 6 | . 2 . |
| . . 6 | . 2 . | 5 . . |
| . 5 . | 4 . 8 | . 1 . |
+-----------+-----------+-----------+
| 7 . . | . 6 . | . . . |
| 8 2 . | 9 . 4 | . 7 . |
| . . . | . . . | 1 8 . |
+-----------+-----------+-----------+
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For the original, click here
Or play online here at dailysudoku.com
This is a puzzle that really needs coloring.
Either the swordfish (Hint: "1", in columns 2,4 and 6)
or two multi-coloring eliminations. (also on "1")
Both remove the same candidates ("1" in r1c5 and r5c1)
If you choose not to go the coloring way, this puzzle gets rather tough.
I found one w-wing (actually two w-wings with the same result),
one generalized xy-wing (17-72-23-31)
one regular xy-wing (34-49-93)
one generalized m-wing (37 in r4c7 via r4c5,r4c9 to 39 in r6c5)
and then - Medusa or chains ... ?
| Code: |
+--------------------------+--------------------------+--------------------------+
| 26 4 3 | 126 19 129 | 8 5 7 |
| 15 8 15 | 3 4 7 | 9 6 2 |
| 9 67 27 | 26 8 5 | 4 3 1 |
+--------------------------+--------------------------+--------------------------+
| 14 9 8 | 5 17 6 | 37 2 34 |
| 134 137 6 | 17 2 39 | 5 49 8 |
| 23 5 27 | 4 39 8 | 67 1 69 |
+--------------------------+--------------------------+--------------------------+
| 7 13 49 | 8 6 13 | 2 49 5 |
| 8 2 15 | 9 15 4 | 36 7 36 |
| 356 36 49 | 27 357 23 | 1 8 49 |
+--------------------------+--------------------------+--------------------------+
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Tue Jul 22, 2008 10:59 pm Post subject: |
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After basics: | Code: | +-------------+-------------+-------------+
| 26 4 3 | 126 19 129 | 8 5 7 |
| 15 8 15 | 3 4 7 | 9 6 2 |
| 9 67 27 | 26 8 5 | 34 34 1 |
+-------------+-------------+-------------+
| 134 9 8 | 5 137 6 | 347 2 34 |
| 134 137 6 | 17 2 139 | 5 349 8 |
| 23 5 27 | 4 379 8 | 367 1 369 |
+-------------+-------------+-------------+
| 7 13 49 | 8 6 13 | 2 49 5 |
| 8 2 15 | 9 15 4 | 36 7 36 |
| 356 36 49 | 27 357 23 | 1 8 49 |
+-------------+-------------+-------------+ |
I found two W-wings to start: One takes out <4> in R4C7, the other takes out <3> in R5C8.
Still looking at it, but a Swordfish is multi-coloring, yes?
Keith |
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tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
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| Posted: Wed Jul 23, 2008 12:13 am Post subject: |
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First I found two w-wings on <34> (that Keith also noted), then when coloring on <1>, I spotted the swordfish (that Nataraj identified) which finished off the puzzle.
Ted |
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nataraj
Joined: 03 Aug 2007
Posts: 1048
Location: near Vienna, Austria
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| Posted: Wed Jul 23, 2008 5:28 am Post subject: |
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| keith wrote: | | Still looking at it, but a Swordfish is multi-coloring, yes? |
I am not really an expert on taxonomy. I look at it from a practical point of view: what results will a certain technique give and what basic principle is it built on?
And I've noticed over and over again that in using my multi-coloring approach (identify strong links in a given candidate and by visualizing "weak" connections between them) I can easily spot x-wing, kite, skyscraper (and all eliminations that follow the "weak"-"strong"-"weak" pattern in a single candidate) but will miss swordfish and jellyfish. I need to go over the diagram a second time and specifically look for these creatures in order to find them.
I think that is because a swordfish or jellyfish also works if some of the units have more than two candidates in them. The elimination is not a simple AIC but based on cell counting (candidate x occurs in the 3/4 rows of a swordfish/jellyfish in exactly 3/4 columns, therefore can be removed from all other rows in those columns) |
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cgordon
Joined: 04 May 2007
Posts: 769
Location: ontario, canada
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| Posted: Wed Jul 23, 2008 2:11 pm Post subject: |
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| All I could find was an ER to remove the 3 from R9C1. This didn't do anything, so I resorted to colouring to remove the 4 from R4C9. Colouring isn't my cup of tea, so I'm not sure whether I applied it correctly or just got lucky in removing the right half of a pair. |
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