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VH+ by JPF (game 0051)

 
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ravel



Joined: 21 Apr 2006
Posts: 536
PostPosted: Fri Sep 26, 2008 1:01 pm    Post subject: VH+ by JPF (game 0051) Reply with quote
Code:
 +-------+-------+-------+
 | 1 . . | . . 2 | . 3 . |
 | . . 2 | 4 . . | 5 . . |
 | . 6 . | . 5 . | . . 7 |
 +-------+-------+-------+
 | . 1 . | . . . | . 8 . |
 | . . 6 | . 3 . | . . 2 |
 | 5 . . | . . . | 6 . . |
 +-------+-------+-------+
 | . 8 . | . . 4 | 9 . . |
 | 7 . . | 5 . . | . . 8 |
 | . . 3 | . 9 . | . 4 . |
 +-------+-------+-------+ JPF
>>> play online

A one trick pony.
This is a typical "swordfish pattern". Only 2 out of more than 10 puzzles i looked at did not need a swordfish (and the second solved with the same trick like this one).
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nataraj



Joined: 03 Aug 2007
Posts: 1048
Location: near Vienna, Austria
PostPosted: Fri Sep 26, 2008 3:46 pm    Post subject: Reply with quote
Ah, "unique" swordfish !

After basics
Code:

+--------------------------+--------------------------+--------------------------+
| 1       7       5        | 689     68      2        | 48      3       469      |
| 89      3       2        | 4       1678    16789    | 5       169     169      |
| 489     6       489      | 189     5       3        | 128     129     7        |
+--------------------------+--------------------------+--------------------------+
| 3       1       479      | 2679    2467    5679     | 47      8       459      |
| 489     49      6        | 1789    3       15789    | 147     1579    2        |
| 5       2       4789     | 1789    1478    1789     | 6       179     3        |
+--------------------------+--------------------------+--------------------------+
| 26      8       1        | 3       267     4        | 9       2567    56       |
| 7       49      49       | 5       126     16       | 3       126     8        |
| 26      5       3        | 12678   9       1678     | 127     4       16       |
+--------------------------+--------------------------+--------------------------+

4 and 9 in r3c13, r5c12 and r8c23 would create a swordfish-like DP, so either r5c1=8 or one of r3c13=8. In both cases r2c1=9
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keith



Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
PostPosted: Fri Sep 26, 2008 9:26 pm    Post subject: Reply with quote
nataraj wrote:
4 and 9 in r3c13, r5c12 and r8c23 would create a swordfish-like DP, so either r5c1=8 or one of r3c13=8. In both cases r2c1=9

Just to be pedantic:
... so r5c1=8 and/or one or both of r3c13=8
is more precise.

Keith Smile
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daj95376



Joined: 23 Aug 2008
Posts: 3854
PostPosted: Sat Sep 27, 2008 4:33 am    Post subject: Reply with quote
keith wrote:
Just to be pedantic:
... so r5c1=8 and/or one or both of r3c13=8
is more precise.

More precise, I don't think so.

r5c1=8 and r3c1=8 doesn't work!
both of r3c13=8 doesn't work, either!

At least one of r5c1=8, r1c1|3=8.
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Asellus



Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA
PostPosted: Sat Sep 27, 2008 4:39 am    Post subject: Reply with quote
keith wrote:
Just to be pedantic:
... so r5c1=8 and/or one or both of r3c13=8
is more precise.

Maybe a bit too pedantic: How, exactly, can r3c1 and r3c3 both be <8>?

The most precise way to state it in this sort of language would be: r3c1 is <8> or r3c3 and/or r5c1 is <8>.

From nataraj's statement, I suspect that what he was actually thinking was that the <8> in r5c1 has a strong inference link with the grouped <8>s in r3c13. And if so, that is a correct. But, the "and/or" type wording of nataraj has the same problem because r5c1 and r3c1 cannot both by <8>.

[Edit: daj's post showed up while I was working on mine!]
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nataraj



Joined: 03 Aug 2007
Posts: 1048
Location: near Vienna, Austria
PostPosted: Sat Sep 27, 2008 6:43 am    Post subject: Reply with quote
keith wrote:

Just to be pedantic:
... so r5c1=8 and/or one or both of r3c13=8
is more precise.

Keith Smile


You are right, Keith. Getting sloppy, here (too much travelling, too much relaxation, too much sun and warm weather) Wink.

Of course the phrase "either/or" is wrong and I really meant an inclusive or.

BTW, I did like you said you would and took a pile of sudokus on my vacation, "VH"s from 2007 and some others. I had a great time (and no internet access Laughing)
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