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DB Saturday Puzzle: July 7, 2007

 
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keith



Joined: 19 Sep 2005
Posts: 3184
Location: near Detroit, Michigan, USA

PostPosted: Sat Jul 07, 2007 2:40 pm    Post subject: DB Saturday Puzzle: July 7, 2007 Reply with quote

I have not yet completed this one ...
Code:
Puzzle: DB070707  ******
+-------+-------+-------+
| . 8 . | . . . | 6 . 5 |
| 1 . 6 | . . . | . 8 2 |
| . . 3 | . . . | 4 . . |
+-------+-------+-------+
| 8 . . | . . 6 | . . . |
| . . 9 | 8 5 4 | 3 . . |
| . . . | 9 . . | . . 7 |
+-------+-------+-------+
| . . 8 | . . . | 9 . . |
| 3 2 . | . . . | 5 . 4 |
| 9 . 5 | . . . | . 7 . |
+-------+-------+-------+


Keith
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Earl



Joined: 30 May 2007
Posts: 546
Location: St Louis MO

PostPosted: Sat Jul 07, 2007 4:34 pm    Post subject: DB July 7 Reply with quote

I got this far using basic techniques.

The next step eludes me.

Earl

Code:

+-----------+---------------+---------+
| 4  8   27 | 127 1279 1279 | 6  3  5 |
| 1  9   6  | 345 34   35   | 7  8  2 |
| 27 5   3  | 6   278  278  | 4  9  1 |
+-----------+---------------+---------+
| 8  3   4  | 127 127  6    | 12 5  9 |
| 27 17  9  | 8   5    4    | 3  12 6 |
| 5  6   12 | 9   123  123  | 8  4  7 |
+-----------+---------------+---------+
| 6  147 8  | 45  1247 1257 | 9  12 3 |
| 3  2   17 | 17  89   89   | 5  6  4 |
| 9  14  5  | 34  6    123  | 12 7  8 |
+-----------+---------------+---------+

Play this puzzle online at the Daily Sudoku site
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ravel



Joined: 21 Apr 2006
Posts: 536

PostPosted: Sat Jul 07, 2007 4:37 pm    Post subject: Reply with quote

SS is stuck here:
Code:
 *--------------------------------------------------------------------*
 | 4      8      27     | 127    1279   1279   | 6      3      5      |
 | 1      9      6      | 345    34     35     | 7      8      2      |
 | 257    57     3      | 267    2678   278    | 4      9      1      |
 |----------------------+----------------------+----------------------|
 | 8      35     124    | 237    1237   6      | 12     45     9      |
 |@27    #17     9      | 8      5      4      | 3     @12     6      |
 | 56     356    124    | 9      123    123    | 8      45     7      |
 |----------------------+----------------------+----------------------|
 | 6-7   #1467   8      | 24567  2467   257    | 9      12     3      |
 | 3      2     @17     | 17     89     89     | 5      6      4      |
 | 9      46     5      | 12346  12346  123    | 12     7      8      |
 *--------------------------------------------------------------------*
There is no W-Wing for the 17's, but with the strong link for 1 in column 2 there is a similar deduction:
Either r5c2=1 => r5c1=7
or r7c2=1 => r8c3=7
So r6c1<>7.

Earl: There are 2 strong links (Kite) to remove 1 from r9c2 in your grid.
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Asellus



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

PostPosted: Sat Jul 07, 2007 11:19 pm    Post subject: Reply with quote

I didn't see Ravel's "Kite" (or coloring on <1>), but I still was able to make the <7> elimination using a slightly novel coloring:
Code:
+-------------------+
| 4     8       27  |
| 1     9       6   |
| 257   57      3   |
+-------------------+
| 8     35   (1r)24 |
| 27g   1g7r    9   |
| 56    356  (1r)24 |
+-------------------+
| 6-7  (1r)467   8  |
| 3      2     1g7r |
| 9    (1r)46    5  |
+-------------------+

Notice that there is a strong link on <1> between C2 and C3 in Boxes 4 and 7. I've used parentheses to denote this in the coloring, with red(r) and green(g). The <7> at R7C1 can see both colors of <7>.

Employing the Kite elimination plus a number of other steps, I was able to solve the puzzle. It reminded me of Ravel's posting of yesterday: a tough nut to crack that didn't submit easily.
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ravel



Joined: 21 Apr 2006
Posts: 536

PostPosted: Sun Jul 08, 2007 7:57 pm    Post subject: Reply with quote

Asellus wrote:
I didn't see Ravel's "Kite" (or coloring on <1>)

Code:
+------------+---------------+---------+
| 4   8   27 | 127 1279 1279 | 6  3  5 |
| 1   9   6  | 345 34   35   | 7  8  2 |
| 27  5   3  | 6   278  278  | 4  9  1 |
+------------+---------------+---------+
| 8   3   4  | 127 127  6    | 12 5  9 |
| 27 A17  9  | 8   5    4    | 3 B12 6 |
| 5   6   12 | 9   123  123  | 8  4  7 |
+------------+---------------+---------+
| 6   147 8  | 45  1247 1257 | 9 A12 3 |
| 3   2   17 | 17  89   89   | 5  6  4 |
| 9  -14  5  | 34  6    123  |B12 7  8 |
+------------+---------------+---------+
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jLo



Joined: 30 Apr 2007
Posts: 55

PostPosted: Mon Jul 09, 2007 12:21 am    Post subject: Reply with quote

Quote:

I got this far using basic techniques.

The next step eludes me.


There is a skyscraper on <2>s which solves R6C3 and pretty much wraps things up.
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TexCat



Joined: 07 Jul 2006
Posts: 31

PostPosted: Mon Jul 09, 2007 3:09 am    Post subject: Reply with quote

I got stuck way back at:
Code:

+----------------+-------------------+----------+
| 247  8     247 | 127    1279  1279 | 6  3   5 |
| 1    9     6   | 345    34    35   | 7  8   2 |
| 257  57    3   | 267    2678  278  | 4  9   1 |
+----------------+-------------------+----------+
| 8    1345  124 | 1237   1237  6    | 12 45  9 |
| 27   17    9   | 8      5     4    | 3  12  6 |
| 2456 13456 124 | 9      123   123  | 8  45  7 |
+----------------+-------------------+----------+
| 467  1467  8   | 124567 12467 1257 | 9  126 3 |
| 3    2     17  | 167    89    89   | 5  16  4 |
| 9    146   5   | 12346  12346 123  | 12 7   8 |
+----------------+-------------------+----------+

Play this puzzle online at the Daily Sudoku site

What am I missing here?
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Marty R.



Joined: 12 Feb 2006
Posts: 5179
Location: Rochester, NY, USA

PostPosted: Mon Jul 09, 2007 4:37 am    Post subject: Reply with quote

Quote:
What am I missing here?


Same thing that I'm missing, because I'm stuck in the same place except I only have 24 in r1c1.
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ravel



Joined: 21 Apr 2006
Posts: 536

PostPosted: Mon Jul 09, 2007 7:29 am    Post subject: Reply with quote

Code:
+----------------+-------------------+----------+
| 247  8     247 | 127    1279  1279 | 6  3   5 |
| 1    9     6   | 345    34    35   | 7  8   2 |
| 257  57    3   | 267    2678  278  | 4  9   1 |
+----------------+-------------------+----------+
| 8    1345  124 | 1237   1237  6    | 12 45  9 |
| 27   17    9   | 8      5     4    | 3  12  6 |
| 2456 13456 124 | 9      123   123  | 8  45  7 |
+----------------+-------------------+----------+
| 467  1467  8   | 124567 12467 1257 | 9  126 3 |
| 3    2     17  | 167    89    89   | 5  16  4 |
| 9    146   5   | 12346  12346 123  | 12 7   8 |
+----------------+-------------------+----------+
Hard to spot: There is a hidden triple 356 (or naked quad 1247) in box 4.
I really recommend to use a program, after one has tried hard and is still stuck. How often did i miss basic moves !
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Marty R.



Joined: 12 Feb 2006
Posts: 5179
Location: Rochester, NY, USA

PostPosted: Mon Jul 09, 2007 3:52 pm    Post subject: Reply with quote

Quote:
Hard to spot: There is a hidden triple 356 (or naked quad 1247) in box 4.


I'll take the quad over the hidden triple. Thanks, there's no excuse for missing that.
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TKiel



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

PostPosted: Mon Jul 09, 2007 11:15 pm    Post subject: Reply with quote

jLo wrote:
There is a skyscraper on <2>s which solves R6C3...

in regards to Earl's post.

I don't see this, but I do see the following multi-coloring option.

Code:
 
 *-----------------------------------------------------------*
 | 4     8     27A   | 127B  1279  1279  | 6     3     5     |
 | 1     9     6     | 345   34    35    | 7     8     2     |
 | 27a   5     3     | 6     278   278   | 4     9     1     |
 |-------------------+-------------------+-------------------|
 | 8     3     4     | 127b  127   6     | 12A   5     9     |
 | 27A   17    9     | 8     5     4     | 3     12a   6     |
 | 5     6     12    | 9     123   123   | 8     4     7     |
 |-------------------+-------------------+-------------------|
 | 6     147   8     | 45    1247  1257  | 9     12    3     |
 | 3     2     17    | 17    89    89    | 5     6     4     |
 | 9     14    5     | 34    6     123   | 12    7     8     |
 *-----------------------------------------------------------*


Both ends of the [B,b] chain see an A cell from the other chain, indicating that none of the cells marked with an A can be true.
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jLo



Joined: 30 Apr 2007
Posts: 55

PostPosted: Fri Jul 13, 2007 12:49 am    Post subject: Reply with quote

TKiel wrote:
jLo wrote:
There is a skyscraper on <2>s which solves R6C3...

in regards to Earl's post.

I don't see this, but I do see the following multi-coloring option.


Code:

+-----------+---------------+---------+
| 4  8  x27 |x127 1279 1279 | 6  3  5 |
| 1  9   6  | 345 34   35   | 7  8  2 |
| 27 5   3  | 6   278  278  | 4  9  1 |
+-----------+---------------+---------+
| 8  3   4  |x127 127  6    | 12 5  9 |
| 27 17  9  | 8   5    4    | 3  12 6 |
| 5  6  x12 | 9  X123 X123  | 8  4  7 |

+-----------+---------------+---------+
| 6  147 8  | 45  1247 1257 | 9  12 3 |
| 3  2   17 | 17  89   89   | 5  6  4 |
| 9  14  5  | 34  6    123  | 12 7  8 |
+-----------+---------------+---------+


Either one or both of R6C3 and R4C4 are <2>. Thus, <2> can be eliminated
from their common buddies - R6C5 and R6C6. This leaves a naked pair <13>
on Row 6, eliminating the 2 from R6C3.
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