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Oct 22 VH

 
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Earl



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

PostPosted: Wed Oct 22, 2008 2:24 am    Post subject: Oct 22 VH Reply with quote

1-2-7 xy-wing, BINGO !

Earl
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crunched



Joined: 05 Feb 2008
Posts: 168

PostPosted: Wed Oct 22, 2008 5:04 am    Post subject: Re: Oct 22 VH Reply with quote

Earl wrote:
1-2-7 xy-wing, BINGO !

Earl


Yep, it took me about 7-8 minutes for this easy vh puzzle. That means the wizards will have it resolved in prolly 30-40 seconds.
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storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Wed Oct 22, 2008 7:08 am    Post subject: Reply with quote

pretty happy about this one. but again, like in some puzzles in the past, the placement of the xy-wing in the 8-9 box area probably caused an extra minute to locate. for some reason my eyes don't automatically jump to that part of the puzzle.
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arkietech



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

PostPosted: Wed Oct 22, 2008 11:59 am    Post subject: Reply with quote

Code:
 *-----------*
 |.19|...|...|
 |2.7|..9|...|
 |.8.|16.|...|
 |---+---+---|
 |1.6|.7.|.4.|
 |8..|...|..6|
 |.4.|.3.|9.5|
 |---+---+---|
 |...|.45|.2.|
 |...|9..|6.3|
 |...|...|85.|
 *-----------*
 *-----------------------------------------------------------*
 | 3456  1     9     | 247   25    2347  | 245   36    8     |
 | 2     36    7     | 48    58    9     | 45    36    1     |
 | 345   8     345   | 1     6     234   | 245   9     7     |
 |-------------------+-------------------+-------------------|
 | 1     9     6     | 5     7     8     | 3     4     2     |
 | 8     35    35    | 24    9     24    | 17    17    6     |
 | 7     4     2     | 6     3     1     | 9     8     5     |
 |-------------------+-------------------+-------------------|
 | 36    367   138   | 378   4     5     | 17    2     9     |
 | 45    257   1458  | 9     128   27    | 6     17    3     |
 | 9     237   13    | 237   12    6     | 8     5     4     |
 *-----------------------------------------------------------*

Anyone see another solution?
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Earl



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

PostPosted: Wed Oct 22, 2008 1:44 pm    Post subject: Oct 22 VH Reply with quote

Dan,

I can do it with two xy-chains, but that is not very elegant.

Earl
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nataraj



Joined: 03 Aug 2007
Posts: 1048
Location: near Vienna, Austria

PostPosted: Thu Oct 23, 2008 7:32 pm    Post subject: Reply with quote

arkietech wrote:

Anyone see another solution?


Dan,
I see another possibility, but not in the usual ("vh") x-,xy-,xyz-wing domain.

Code:
 
 *-----------------------------------------------------------*
 | 3456  1     9     | 247   25    2347  | 245   36    8     |
 | 2     36    7     | 48    58    9     | 45    36    1     |
 | 345   8     345   | 1     6     234   | 245   9     7     |
 |-------------------+-------------------+-------------------|
 | 1     9     6     | 5     7     8     | 3     4     2     |
 | 8     35    35    | 24    9     24    | 17    17    6     |
 | 7     4     2     | 6     3     1     | 9     8     5     |
 |-------------------+-------------------+-------------------|
 | 36    367   138   | 3-78  4     5     | 17    2     9     |
 | 45   #257   1458  | 9    1-28  >27<   | 6     17    3     |
 | 9    #23*7  13    | 23*7  12    6     | 8     5     4     |
 *-----------------------------------------------------------*

The bi-value cell r8c6 (marked > <) sees both a strong link on (2) in col 2 and a strong link on (7) in row 9. Both links are connected in cell r9c2.

This allows the elimination of 7 from r6c4 and 2 from r8c5.

With 2 gone from r8c5, that cell is now bi-value (1,8) and it sees the strong link (8) in col 3, which is connected (in r7c3) to a strong link (1) in row 7. This means r8c8 cannot be 1 and the puzzle is solved.
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arkietech



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

PostPosted: Thu Oct 23, 2008 8:20 pm    Post subject: Reply with quote

nataraj wrote:
The bi-value cell r8c6 (marked > <) sees both a strong link on (2) in col 2 and a strong link on (7) in row 9. Both links are connected in cell r9c2.

This allows the elimination of 7 from r6c4 and 2 from r8c5.

With 2 gone from r8c5, that cell is now bi-value (1,8) and it sees the strong link (8) in col 3, which is connected (in r7c3) to a strong link (1) in row 7. This means r8c8 cannot be 1 and the puzzle is solved.


Great Find! What do you call this? I assume you take a bivalue cell and look for strong connections to both values then look for candidates that see both the bivalue cell and the strong link.
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keith



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

PostPosted: Thu Oct 23, 2008 8:43 pm    Post subject: Reply with quote

Quote:
Anyone see another solution?

No, but there is a 4-link XY-wing. <24> and <48> in C4 act like <28>. With <25> and <58> in C5 there is a wing that takes out <2> in R4C1. Not much help.

There is also (I believe) a <36> DP that I could find no use for.

Keith
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nataraj



Joined: 03 Aug 2007
Posts: 1048
Location: near Vienna, Austria

PostPosted: Thu Oct 23, 2008 8:53 pm    Post subject: Reply with quote

I don't call it anything anymore Wink
(suggestions I have offered so far, but none really took off: hockey stick, Harvey Wallbanger)

Actually I look for strong links first (in the course of looking for x-wings, kites, skyscrapers etc.). When I realize that a bi-value cell "sees" such a strong link I check for a connected strong link in the other candidate.

The search is much easier when done with a little helping diagram (the actual drawing does not contain the red and green annotations):
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daj95376



Joined: 23 Aug 2008
Posts: 3854

PostPosted: Thu Oct 23, 2008 9:59 pm    Post subject: Reply with quote

arkietech wrote:
nataraj wrote:
The bi-value cell r8c6 (marked > <) sees both a strong link on (2) in col 2 and a strong link on (7) in row 9. Both links are connected in cell r9c2.

This allows the elimination of 7 from r6c4 and 2 from r8c5.

Great Find! What do you call this?

It's a continuous nice loop: AIC

Code:
7-[r8c6]-2-[r8c2]=2=[r9c2]=7=[r9c4]-7-[r8c6]-2 => [r7c4]<>7, [r8c5]<>2, [r9c2]<>3
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Asellus



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

PostPosted: Thu Oct 23, 2008 10:34 pm    Post subject: Reply with quote

As Danny has pointed out, that AIC loop also removes the <3> in r9c2. All 4 eliminations can also be seen as a Sue de Coq in cells r8c6|r9c345.
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