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June 7

 
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Earl



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

PostPosted: Thu Jun 07, 2007 4:25 pm    Post subject: June 7 Reply with quote

Am I correct that June 7 is solved by two x-y wings:
r2c4,r9c4,r7c5 (eliminatng a 9 in r8c4) and r7c5,r7c9,r8c6 (eliminating 4's in r8c8 and r8c9)?

Earl
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Lynnda



Joined: 07 Jun 2007
Posts: 3
Location: Sydney, Australia

PostPosted: Thu Jun 07, 2007 11:23 pm    Post subject: June 7 Reply with quote

Earl,
Thank you sooooo much. I am just learning to do these XY wings and your tip gave me the right squares to look at and find my first 2 in a "live" situation. Yep, it sure solved the puzzle for me once I had those Very Happy
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Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA

PostPosted: Sat Jun 09, 2007 3:38 pm    Post subject: Re: June 7 Reply with quote

Earl wrote:
Am I correct that June 7 is solved by two x-y wings:
r2c4,r9c4,r7c5 (eliminatng a 9 in r8c4) and r7c5,r7c9,r8c6 (eliminating 4's in r8c8 and r8c9)?

Earl


I guess that's correct if the puzzle got solved. The question implies that there is a standard way to solve, but there are often many ways to solve a given puzzle. In my case there was a Type 4 rectangle which exposed an XY-Wing which solved the puzzle. Overall, this seemed a relatively easy VH.
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Jeff



Joined: 06 May 2007
Posts: 46

PostPosted: Sat Jun 09, 2007 7:10 pm    Post subject: June 7 Reply with quote

I am interested in finding out where the Type 4 Rectangle is in the June 7 puzzle as per Marty R.'s comment. I would also like to find an explanation of the various rectangles. I tried to find a written explanation on all the rectangles that one may run into, but I could not find the site. Could you give me a link to the appropriate site.

Many thanks
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Mesmin



Joined: 01 May 2007
Posts: 12
Location: Ontario

PostPosted: Sat Jun 09, 2007 7:38 pm    Post subject: Reply with quote

Brain Bashers has a good explanation of most of the 'standard' advanced techniques:

http://brainbashers.com/sudokuhelp.asp

The very and super hard puzzles often require (or at least can be) solved with unique rectangles if you want to practice.
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keith



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

PostPosted: Sat Jun 09, 2007 7:52 pm    Post subject: Be Unique! Reply with quote

Basic methods get you to here:
Code:
+----------------+----------------+-----------------+
| 4    1    2    | 7    8    69   | 59    369  35   |
| 7    8    5    | 69   3    1    | 249   469  246  |
| 3    9    6    | 4    5    2    | 1     8    7    |
+----------------+----------------+-----------------+
| 5    6    1    | 3    4    7    | 8     2    9    |
| 8    4    3    | 259# 29   59#  | 6     7    1    |
| 2    7    9    | 1    6    8    | 45    34   35   |
+----------------+----------------+-----------------+
| 6    5    47@  | 8    29   3    | 2479@ 1    24   |
| 1    2    8    | 59#  7    459# | 3     469  46   |
| 9    3    47@  | 26   1    46   | 247@  5    8    |
+----------------+----------------+-----------------+


The Type 4 UR in R79C37 is marked #. You can exclude <4> from R79C7.

Seldom identified, but more common than you might think, is the Type 6 UR marked # in R58C46. (There is one in today's DB puzzle, see the "Other Puzzles" Forum.)

The UR is also an X-wing on <5>. R5C6 and R8C4 must be <5>. If either is <9>, a deadly solution is forced. Similarly, <5> in either of R5C4 or R8C6 forces a deadly solution.

My guide to unique rectangles is here:

http://www.sudoku.com/forums/viewtopic.php?p=29105#29105

Best wishes,
Keith
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