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DB Saturday Puzzle: June 16, 2007

 
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keith



Joined: 19 Sep 2005
Posts: 3136
Location: near Detroit, Michigan, USA

PostPosted: Sat Jun 16, 2007 1:47 pm    Post subject: DB Saturday Puzzle: June 16, 2007 Reply with quote

Code:
Puzzle: DB061607  ******
+-------+-------+-------+
| . 6 . | . . 5 | 2 . . |
| . 8 . | 4 . . | 7 . . |
| . . . | . . . | . 1 8 |
+-------+-------+-------+
| . . 1 | 6 7 . | . . . |
| 9 7 . | . . . | . 5 2 |
| . . . | . 5 4 | 1 . . |
+-------+-------+-------+
| 7 4 . | . . . | . . . |
| . . 8 | . . 3 | . 9 . |
| . . 2 | 8 . . | . 3 . |
+-------+-------+-------+
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TKiel



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

PostPosted: Sat Jun 16, 2007 4:08 pm    Post subject: Reply with quote

Not one of his more challenging ones.
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keith



Joined: 19 Sep 2005
Posts: 3136
Location: near Detroit, Michigan, USA

PostPosted: Sat Jun 16, 2007 5:50 pm    Post subject: Reply with quote

If Tracy finds it not challenging, that is a clue!

Welcome back!

Keith
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Marty R.



Joined: 12 Feb 2006
Posts: 5063
Location: Rochester, NY, USA

PostPosted: Sat Jun 16, 2007 9:08 pm    Post subject: Reply with quote

Hey Tracy, nice to see your name again. Exclamation Very Happy
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Ruud



Joined: 18 Jan 2006
Posts: 31

PostPosted: Sun Jun 17, 2007 12:14 pm    Post subject: Reply with quote

Even though it does not really advance the puzzle (you still need the skyscraper to break it), I found a nice BUG-Lite type 3 in this puzzle:

Code:
.---------------.----------------.---------------.
| 13   6    7   | 139  8     5   | 2    4    39  |
| 123  8    9   | 4   &123   12  | 7    6    5   |
| 4    23   5   | 237  69-23 2679| 39   1    8   |
:---------------+----------------+---------------:
| 23   5    1   | 6    7     29  | 39   8    4   |
| 9    7    4   | 13  &13    8   | 6    5    2   |
| 8    23   6   | 29   5     4   | 1    7    39  |
:---------------+----------------+---------------:
| 7    4    3   | 5    69-1  169 | 8    2    16  |
|#56   1    8   | 27  #246   3   |#45   9    67  |
|#56   9    2   | 8   #146   167 |#45   3    167 |
'---------------'----------------'---------------'


To avoid the deadly 56-46-45 pattern in rows 89, you need 1 or 2 in r89c5. These form a locked set with r25c5, eliminating {123} from the remainder of column 5.

This move makes the puzzle a lot more interesting Smile

Ruud
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Steve R



Joined: 24 Oct 2005
Posts: 289
Location: Birmingham, England

PostPosted: Sun Jun 17, 2007 2:57 pm    Post subject: Reply with quote

Interesting point, Ruud, though, as you say, not immediately productive. This is the diagram position again:

Code:
.---------------.----------------.---------------.
| 13   6    7   | 139  8     5   | 2    4    3-9 |
| 123  8    9   | 4    123   12  | 7    6    5   |
| 4    23   5   | 237  2369  2679| 39*  1    8   |
:---------------+----------------+---------------:
| 23   5    1   | 6    7     29  | 3-9  8    4   |
| 9    7    4   | 13   13    8   | 6    5    2   |
| 8    23   6   | 29   5     4   | 1    7    39* |
:---------------+----------------+---------------:
| 7    4    3   | 5    169   169 | 8    2    16  |
| 56   1    8   | 27   246   3   | 45   9    67  |
| 56   9    2   | 8    146   167 | 45   3    167 |
'---------------'----------------'---------------'

For the time being I seem to be on the lookout for W-Wings before anything else. Here the cells with candidates (39) in boxes 3 and 6 caught my eye. As it happens, two of them (in r3c7 and r6c9) are linked by the conjugates for 3 in the second column.

So one of these two cells contains 9 and the eliminations from r4c7 and r1c9 solve the puzzle at once.

Steve
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keith



Joined: 19 Sep 2005
Posts: 3136
Location: near Detroit, Michigan, USA

PostPosted: Sun Jun 17, 2007 7:59 pm    Post subject: Reply with quote

Basic methods get you to here:
Code:

+----------------+-----------------+----------------+
| 13   6    7    | 139@  8    5    | 2    4    39@  |
| 123  8    9    | 4     123% 12   | 7    6    5    |
| 4    23B  5    | 2379# 2369 2679$| 39   1    8    |
+----------------+-----------------+----------------+
| 23   5    1    | 6     7    29A  | 39   8    4    |
| 9    7    4    | 13    13   8    | 6    5    2    |
| 8    23b  6    | 29@a  5    4    | 1    7    39@  |
+----------------+-----------------+----------------+
| 7    4    3    | 5     169  169  | 8    2    16   |
| 56   1    8    | 27    246  3    | 45   9    67   |
| 56   9    2    | 8     146  167  | 45   3    167  |
+----------------+-----------------+----------------+

There is an X-wing on <9>, labelled @. It takes out <9> from the cell marked #.

The fork (skyscraper, coloring, turbot fish) is composed of two strong links on <2>, marked aA and bB. One of a or b must be false; one of A or B must be true. This takes out <2> from the cell marked $. This reveals an X-wing on <2> in C16, which takes out <2> from %.

This solves the puzzle.

Keith
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Asellus



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

PostPosted: Tue Jun 19, 2007 9:39 pm    Post subject: Well-Skinned Cat Reply with quote

Alternately...

Finned X-Wing on <2> in R2 and R4 (fin is R2C5) eliminates the <2> in R3C6 ($). Then, Swordfish in R3, R6 and R8 takes care of R2C5 (%).
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TKiel



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

PostPosted: Wed Jun 20, 2007 12:56 am    Post subject: Reply with quote

Alternately...

Code:

 
 *--------------------------------------------------------------------*
 | 13     6      79     | 1379   8      5      | 2      4      39     |
 | 123    8      59     | 4      1239   129    | 7      6      359    |
 | 4      23B    579    | 2379   2369   2679   | 359A   1      8      |
 |----------------------+----------------------+----------------------|
 | 23B    5      1      | 6      7      29     | 349a   8      349    |
 | 9      7      4      | 13     13     8      | 6      5      2      |
 | 8      23b    6      | 29     5      4      | 1      7      39     |
 |----------------------+----------------------+----------------------|
 | 7      4      3      | 159    169    169    | 8      2      156    |
 | 56     1      8      | 257    246    3      | 45     9      4567   |
 | 56     9      2      | 8      146    167    | 45     3      14567  |
 *--------------------------------------------------------------------*


Coloring two chains on <3> shows both ends of the A-a chain sharing a row with a B from the other chain, which must be false.
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Ruud



Joined: 18 Jan 2006
Posts: 31

PostPosted: Wed Jun 20, 2007 2:12 am    Post subject: Reply with quote

Alternately...

Code:
.---------------.---------------.---------------.
|-13   6    7   | 139  8    5   | 2    4   *39  |
| 123  8    9   | 4    123  12  | 7    6    5   |
| 4   *23   5   | 237  2369 2679|-39   1    8   |
:---------------+---------------+---------------:
| 23   5    1   | 6    7    29  | 39   8    4   |
| 9    7    4   | 13   13   8   | 6    5    2   |
| 8   *23   6   | 29   5    4   | 1    7   *39  |
:---------------+---------------+---------------:
| 7    4    3   | 5    169  169 | 8    2    16  |
| 56   1    8   | 27   246  3   | 45   9    67  |
| 56   9    2   | 8    146  167 | 45   3    167 |
'---------------'---------------'---------------'

XY-chain: r3c2 - r6c2 - r6c9 - c1c9 eliminates 3 from r1c1 & r3c7.

Alternately...

ER on digit 2 in row 4 and box 1 eliminates 2 from r3c6, followed by an X-wing in r2 & r4 and a naked pair {13} in column 5. A longer road, but more things to see and do Very Happy

Ruud
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Mogulmeister



Joined: 03 May 2007
Posts: 695

PostPosted: Wed Jun 20, 2007 8:01 am    Post subject: Reply with quote

......and of course in Ruud's lovely example you will see that the XY chain is also a skyscraper on 3's.
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Asellus



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

PostPosted: Wed Jun 20, 2007 9:10 am    Post subject: Scenic Route Reply with quote

An ER: Cool!
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Mogulmeister



Joined: 03 May 2007
Posts: 695

PostPosted: Wed Jun 20, 2007 10:54 am    Post subject: Reply with quote

.....that's an Empty Rectangle for those that haven't come across it yet.

http://www.sudocue.net/guide.php#EmptyRectange
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