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Aug 28 VH
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Earl



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

PostPosted: Tue Aug 28, 2007 2:08 pm    Post subject: Aug 28 VH Reply with quote

Two back-door compact xy-wings, eliminating 3 from R4C4 and 5 from R8C5, leaves only singles.

Earl
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jLo



Joined: 30 Apr 2007
Posts: 55

PostPosted: Tue Aug 28, 2007 2:34 pm    Post subject: Reply with quote

The easiest VH in recent memory, I think.

There are a couple of different XY-wings and a couple of
W-Wings after the first XY-wing that Earl noted, any one of
which breaks the whole thing open.
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George Woods



Joined: 28 Mar 2006
Posts: 304
Location: Dorset UK

PostPosted: Tue Aug 28, 2007 4:14 pm    Post subject: completely different solution Reply with quote

Code:

+---------+--------------+----------+
| 1  4 7  | 35  6    35  | 8   2 9  |
| 2  3 6  | 9   8    4   | 7   1 5  |
| 9  5 8  | 2   1    7   | 4   6 3  |
+---------+--------------+----------+
| 8  9 24 | 346 34   1   | 26  5 7  |
| 6  7 45 | 45  2    8   | 9   3 1  |
| 3  1 25 | 7   59   569 | 26  4 8  |
+---------+--------------+----------+
| 45 6 1  | 8   3459 359 | 35  7 2  |
| 7  2 9  | 1   345  356 | 356 8 46 |
| 45 8 3  | 456 7    2   | 1   9 46 |
+---------+--------------+----------+

Play this puzzle online at the Daily Sudoku site

For me I noticed that r4c4 acts as a hinge to a type of wing:- If 6 then the 45s in col4 deny a 5 in r1c4 and if not a 6 then the 34s make r5c4 5 again denying a 5 to r1c4 which must be 3, two moves further on a BUG+1 arises and from there it is plain sailing.


Many ways to skin a cat!
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Marty R.



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

PostPosted: Tue Aug 28, 2007 7:06 pm    Post subject: Reply with quote

I just couldn't find any wings, not X, XY, XYZ or W. The grid above should not have a 6 in r8c7. I solved a cell based on the implications of that 35 UR in boxes 8 and 9. After the eliminations therefrom, that 35 rectangle became a Type 1 which solved the puzzle.
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sdq_pete



Joined: 30 Apr 2007
Posts: 119
Location: Rotterdam, NL

PostPosted: Tue Aug 28, 2007 7:55 pm    Post subject: Reply with quote

Well, I know that the XY wing with pivot 45 at R5C4 and pincers 35 and 34 at R1C4 and R4C5, eliminating the 3 at R4C4, opened the "end phase" for me.

Peter
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Marty R.



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

PostPosted: Tue Aug 28, 2007 9:55 pm    Post subject: Reply with quote

Quote:
Well, I know that the XY wing with pivot 45 at R5C4 and pincers 35 and 34 at R1C4 and R4C5, eliminating the 3 at R4C4, opened the "end phase" for me.


I never cease to be amazed at how much I can miss that's right out there in plain view. Rolling Eyes
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TKiel



Joined: 22 Feb 2006
Posts: 292
Location: Kalamazoo, MI

PostPosted: Wed Aug 29, 2007 8:53 pm    Post subject: Reply with quote

Quote:
I never cease to be amazed at how much I can miss that's right out there in plain view.


Wouldn't we all be better solvers (and people, too) if this never happened?

And, not that it's only applicable to this puzzle, I can't recall a prior run of 5 VH's in 9 days. Three cheers for Sam!
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cgordon



Joined: 04 May 2007
Posts: 769
Location: ontario, canada

PostPosted: Thu Aug 30, 2007 6:43 pm    Post subject: Reply with quote

Quote:
The easiest VH in recent memory, I think.


Not sure about that !

I had to use two xy wings and one x wing (which seems typical from posts). Many of recent VHs required only one xy - or even one x wing.
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Myth Jellies



Joined: 27 Jun 2006
Posts: 64

PostPosted: Thu Aug 30, 2007 8:16 pm    Post subject: Re: completely different solution Reply with quote

George Woods wrote:
Code:

+---------+--------------+----------+
| 1  4 7  | 35  6    35  | 8   2 9  |
| 2  3 6  | 9   8    4   | 7   1 5  |
| 9  5 8  | 2   1    7   | 4   6 3  |
+---------+--------------+----------+
| 8  9 24 | 346 34   1   | 26  5 7  |
| 6  7 45 | 45  2    8   | 9   3 1  |
| 3  1 25 | 7  *59  *569 | 26  4 8  |
+---------+--------------+----------+
| 45 6 1  | 8  *3459*359 |*35  7 2  |
| 7  2 9  | 1  *345 *356 |*35  8 46 |
| 45 8 3  | 456 7    2   | 1   9 46 |
+---------+--------------+----------+

...Many ways to skin a cat!


Here is another that isn't too hard to see, but you don't find it too often. The starred cells (r6c56, r7c567, r8c567) are in danger of forming a MUG using the digits 3569. The only way to avoid the MUG is to have r78c5 = 4 which eliminates the 4's in r4c5 and r9c4. After solving a few cells, you are left with a simple BUG+1 grid to finish.
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KSipher



Joined: 24 Sep 2006
Posts: 38

PostPosted: Sat Sep 01, 2007 1:42 am    Post subject: 8/28 Still stuck Reply with quote

Hi

I am stuck at this point. Can someone suggest what to look for?

Thanks
Kathy

Code:

+---------+-----------+---------+
| 1  4 7  | 3  6   5  | 8  2 9  |
| 2  3 6  | 9  8   4  | 7  1 5  |
| 9  5 8  | 2  1   7  | 4  6 3  |
+---------+-----------+---------+
| 8  9 24 | 46 3   1  | 26 5 7  |
| 6  7 45 | 45 2   8  | 9  3 1  |
| 3  1 25 | 7  59  69 | 26 4 8  |
+---------+-----------+---------+
| 45 6 1  | 8  459 39 | 35 7 2  |
| 7  2 9  | 1  45  36 | 35 8 46 |
| 45 8 3  | 56 7   2  | 1  9 46 |
+---------+-----------+---------+

Play this puzzle online at the Daily Sudoku site
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KSipher



Joined: 24 Sep 2006
Posts: 38

PostPosted: Sat Sep 01, 2007 1:50 am    Post subject: BUG?? Reply with quote

Hi,
I just posted a question and now I am wondering if this is a sample of a BUG removal? If I remove the 5 from row 7 column 5, then is this a sample of a BUG? So does that mean that row 7 column 5 must be a 5??

Code:

+---------+-----------+---------+
| 1  4 7  | 3  6   5  | 8  2 9  |
| 2  3 6  | 9  8   4  | 7  1 5  |
| 9  5 8  | 2  1   7  | 4  6 3  |
+---------+-----------+---------+
| 8  9 24 | 46 3   1  | 26 5 7  |
| 6  7 45 | 45 2   8  | 9  3 1  |
| 3  1 25 | 7  59  69 | 26 4 8  |
+---------+-----------+---------+
| 45 6 1  | 8  459 39 | 35 7 2  |
| 7  2 9  | 1  45  36 | 35 8 46 |
| 45 8 3  | 56 7   2  | 1  9 46 |
+---------+-----------+---------+

Play this puzzle online at the Daily Sudoku site

Thanks for your help
Kathy
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Marty R.



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

PostPosted: Sat Sep 01, 2007 3:48 am    Post subject: Reply with quote

Kathy, yes to all your questions. The pattern in your grid is usually referred to as a BUG+1.
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KSipher



Joined: 24 Sep 2006
Posts: 38

PostPosted: Sat Sep 01, 2007 5:41 pm    Post subject: BUG!! Reply with quote

Awesome, I found my first BUG and I even understand it!!
Thanks,
Kathy
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Luke451



Joined: 20 Apr 2008
Posts: 310
Location: Southern Northern California

PostPosted: Thu Mar 04, 2010 8:01 am    Post subject: Re: completely different solution Reply with quote

Myth Jellies wrote:
George Woods wrote:
Code:

+---------+--------------+----------+
| 1  4 7  | 35  6    35  | 8   2 9  |
| 2  3 6  | 9   8    4   | 7   1 5  |
| 9  5 8  | 2   1    7   | 4   6 3  |
+---------+--------------+----------+
| 8  9 24 | 346 34   1   | 26  5 7  |
| 6  7 45 | 45  2    8   | 9   3 1  |
| 3  1 25 | 7  *59  *569 | 26  4 8  |
+---------+--------------+----------+
| 45 6 1  | 8  *3459*359 |*35  7 2  |
| 7  2 9  | 1  *345 *356 |*35  8 46 |
| 45 8 3  | 456 7    2   | 1   9 46 |
+---------+--------------+----------+

...Many ways to skin a cat!


Here is another that isn't too hard to see, but you don't find it too often. The starred cells (r6c56, r7c567, r8c567) are in danger of forming a MUG using the digits 3569. The only way to avoid the MUG is to have r78c5 = 4 which eliminates the 4's in r4c5 and r9c4. After solving a few cells, you are left with a simple BUG+1 grid to finish.

I'm wondering if any of you mugs could help me out with this one. I know this is ancient history, but I found it while doing a little research.

I cannot see the MUG on (3569). The (6)s don't seem right in there. I guess the L-shape might be throwing me off.

What am I missing?
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storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Thu Mar 04, 2010 6:20 pm    Post subject: Reply with quote

here is a link to the pattern.

http://www.sudoku.com/boards/viewtopic.php?t=3210&start=0

but I agree with you Luke, I am scratching my head over this one.
if we apply what the pattern is we get this

Code:
+-------+------------+--------+
| . . . | . .    .   | .  . . |
| . . . | . .    .   | .  . . |
| . . . | . .    .   | .  . . |
+-------+------------+--------+
| . . . | . .    .   | .  . . |
| . . . | . .    .   | .  . . |
| . . . | . 59   569 | .  . . |
+-------+------------+--------+
| . . . | . 3459 359 | 35 . . |
| . . . | . 345  .   | 35 . . |
| . . . | . .    .   | .  . . |
+-------+------------+--------+



according to Myth Jellies,
the deadly pattern is


Code:

+-------+----------+--------+
| . . . | . .   .  | .  . . |
| . . . | . .   .  | .  . . |
| . . . | . .   .  | .  . . |
+-------+----------+--------+
| . . . | . .   .  | .  . . |
| . . . | . .   .  | .  . . |
| . . . | . 59  59 | .  . . |
+-------+----------+--------+
| . . . | . 359 59 | 35 . . |
| . . . | . 35  .  | 35 . . |
| . . . | . .   .  | .  . . |
+-------+----------+--------+


the extra candidates in the grid are
6 in r6c6
3 in r7c6
4's in r78c5

so the question is how are the 4's solely responsible for the destruction of the deadly pattern?
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strmckr



Joined: 18 Aug 2009
Posts: 64

PostPosted: Fri Mar 05, 2010 5:57 am    Post subject: Reply with quote

Code:
+-------+----------+--------+
| . . . | . .   .  | .  . . |
| . . . | . .   .  | .  . . |
| . . . | . .   .  | .  . . |
+-------+----------+--------+
| . . . | . .   .  | .  . . |
| . . . | . .   .  | .  . . |
| . . . | . 59  59 | .  . . |
+-------+----------+--------+
| . . . | . 359 59 | 35 . . |
| . . . | . 35  .  | 35 . . |
| . . . | . .   .  | .  . . |
+-------+----------+--------+


with in the pattern displayed above there is both a

35-35
35-35

unique rectangle & a

59 - 59
59 - 59

unique rectangle

rectangle linked as 1 unit where by any combination of 3/5/9 yields 2 solution outcomes.

the only way to prevent the pattern from completing either or is to have one of the two cells in question = 4.

R8C5 or R7C5
so yes the 4 is responsible for preventing that pattern from completing.

so any 4 out side the pattern that sees these two cells must be false
ie R4C5 <> 4


in regards to the mug

Code:
+---------+--------------+----------+
| 1  4 7  | 35  6    35  | 8   2 9  |
| 2  3 6  | 9   8    4   | 7   1 5  |
| 9  5 8  | 2   1    7   | 4   6 3  |
+---------+--------------+----------+
| 8  9 24 | 346 34   1   | 26  5 7  |
| 6  7 45 | 45  2    8   | 9   3 1  |
| 3  1 25 | 7  *59  *569 | 26  4 8  |
+---------+--------------+----------+
| 45 6 1  | 8  *3459*359 |*35  7 2  |
| 7  2 9  | 1  *345 *356 |*35  8 46 | notice the bi location of 4 & 6
| 45 8 3  | 456 7    2   | 1   9 46 |
+---------+--------------+----------+
                     |
                     ---------------------(notice the bi location of 6 on the column


if R8C9 = 6 then R8C5 =4 (bug is avoided)
if R8C9 = 4 then R7C5 =4 (bug is avoided)
if R7C6 = 6 => R8C9 = 4 => R7C5=4 (bug is avoided)

(the bug being displayed above)

this is why it is called multivalued.

no matter how specific digits are arranged the bug still is present or avoided.
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storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Fri Mar 05, 2010 2:59 pm    Post subject: Reply with quote

Quote:
if R8C9 = 6 then R8C5 =4 (bug is avoided)
if R8C9 = 4 then R7C5 =4 (bug is avoided)
if R7C6 = 6 => R8C9 = 4 => R7C5=4 (bug is avoided)

(the bug being displayed above)

this is why it is called multivalued.

no matter how specific digits are arranged the bug still is present or avoided


why didn't Myth Jellies explain it this way?
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Luke451



Joined: 20 Apr 2008
Posts: 310
Location: Southern Northern California

PostPosted: Fri Mar 05, 2010 3:15 pm    Post subject: Reply with quote

Gents, first off, thanks for looking at that for me. I'm still not outta the woods, tho.

No biggie, but it has to be misleading to say this is a (3569) MUG.

storm_norm wrote:
the extra candidates in the grid are
6 in r6c6
3 in r7c6
4's in r78c5

StrmCkr, do you agree that these are the "internal outs?"
Code:
*-----------------------------------------------------------*
 | 1     4     7     | 35    6     35    | 8     2     9     |
 | 2     3     6     | 9     8     4     | 7     1     5     |
 | 9     5     8     | 2     1     7     | 4     6     3     |
 |-------------------+-------------------+-------------------|
 | 8     9     24    | 346  -43    1     | 26    5     7     |
 | 6     7     45    | 45    2     8     | 9     3     1     |
 | 3     1     25    | 7    *59   *59+6  | 26    4     8     |
 |-------------------+-------------------+-------------------|
 | 45    6     1     | 8   *359+4 *59+3  |*35    7     2     |
 | 7     2     9     | 1   *35+4   356   |*35    8     46    |
 | 45    8     3     |-456   7     2     | 1     9     46    |
 *-----------------------------------------------------------*

How do you account for (3)r7c6 leading to the two -(4)s?

StrmCkr wrote:
if R8C9 = 4 then R7C5 =4 (bug is avoided)

Sorry, Seeker, I must have blinders on. I don't see that either Sad .

Below is another (359) MUG, with no L-shape into box 9. I can’t get the elims from this one either, though!

Code:
 *-----------------------------------------------------------*
 | 1     4     7     | 35    6     35    | 8     2     9     |
 | 2     3     6     | 9     8     4     | 7     1     5     |
 | 9     5     8     | 2     1     7     | 4     6     3     |
 |-------------------+-------------------+-------------------|
 | 8     9     24    | 346   43    1     | 26    5     7     |
 | 6     7     45    | 45    2     8     | 9     3     1     |
 | 3     1     25    | 7    *59   *59+6  | 26    4     8     |
 |-------------------+-------------------+-------------------|
 | 45    6     1     | 8    *359+4 *359  | 35    7     2     |
 | 7     2     9     | 1    *35+4  *35+6 | 35    8     46    |
 | 45    8     3     | 456   7     2     | 1     9     46    |
 *-----------------------------------------------------------*
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strmckr



Joined: 18 Aug 2009
Posts: 64

PostPosted: Sat Mar 06, 2010 12:37 am    Post subject: Reply with quote

Code:
*-----------------------------------------------------------*
 | 1     4     7     | 35    6     35    | 8     2     9     |
 | 2     3     6     | 9     8     4     | 7     1     5     |
 | 9     5     8     | 2     1     7     | 4     6     3     |
 |-------------------+-------------------+-------------------|
 | 8     9     24    | 346   3-4   1     | 26    5     7     |
 | 6     7     45    | 45    2     8     | 9     3     1     |
 | 3     1     25    | 7    *59   *59+6  | 26    4     8     |
 |-------------------+-------------------+-------------------|
 | 45    6     1     | 8    *359+4 *359  | *35   7     2     |
 | 7     2     9     | 1    *35+4  *35+6 | *35   8     46    |
 | 45    8     3     | 56-4  7     2     | 1     9     46    |
 *-----------------------------------------------------------*


u posted the same grid twice?

there is a Hidden Rectangle: 5/9 in r6c56,r7c56 => r7c6<>5
& the mug as well..
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Luke451



Joined: 20 Apr 2008
Posts: 310
Location: Southern Northern California

PostPosted: Sat Mar 06, 2010 2:27 am    Post subject: Reply with quote

strmckr wrote:

u posted the same grid twice?

there is a Hidden Rectangle: 5/9 in r6c56,r7c56 => r7c6<>5
& the mug as well..

Same grid, yes, but if you look closely, the second MUG is not the same as the first. My point is, I can't see how either takes out the (4)s in the original post.

I see the hidden UR elim, but my bete noire is the MUG, not URs.

I'll put it aside for a few days. When I look again, I'm sure the clouds will part.
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