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Set H Puzzle 13

 
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daj95376



Joined: 23 Aug 2008
Posts: 3855

PostPosted: Fri Dec 26, 2008 10:01 pm    Post subject: Set H Puzzle 13 Reply with quote

Code:
 +-----------------------+
 | . . 2 | . 4 . | . . 7 |
 | . 8 . | . . . | 4 . . |
 | 1 . 6 | 3 . . | 2 . . |
 |-------+-------+-------|
 | . . 8 | . . . | 9 4 . |
 | 2 . . | . 9 . | . . 6 |
 | . . . | . . 3 | . . . |
 |-------+-------+-------|
 | . 2 7 | 9 . . | 6 . 1 |
 | . . . | 8 . . | . . . |
 | 3 . . | . 2 . | 7 . 9 |
 +-----------------------+

Play this puzzle online at the Daily Sudoku site
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tlanglet



Joined: 17 Oct 2007
Posts: 2461
Location: Northern California Foothills

PostPosted: Sun Dec 28, 2008 12:35 am    Post subject: Reply with quote

I used six steps to solve this puzzle but have no idea what was really required; three steps were URs with overlaying x-wings!

Quote:
skyscraper <3>
ER <5>
UR <59> with x-wing <9>
UR <57> with x-wing <7>
UR <67> with x-wing <7>
xyz <156>

Ted
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storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Fri Jan 02, 2009 8:30 am    Post subject: Reply with quote

Code:
.---------------------.---------------------.---------------------.
| 59     359    2     | 156    4      15689 | 1358   13569  7     |
| 7      8     *359   | 1256   156    12569 | 4      13569 *35    |
| 1      4      6     | 3      578    5789  | 2      59     58    |
:---------------------+---------------------+---------------------:
| 56     13567  8     | 12567  156    1256  | 9      4     *235   |
| 2      1357  *135   | 4      9      158   | 1358   1357   6     |
| 4      15679  159   | 12567  1568   3     | 158    157    258   |
:---------------------+---------------------+---------------------:
| 8      2      7     | 9      35     4     | 6      35     1     |
| 569    1569   159   | 8      13567  1567  | 35     2      4     |
| 3      156    4     | 156    2      156   | 7      8      9     |
'---------------------'---------------------'---------------------'

the marked skyscraper on 3's goes a long way.

then I found this mixed w-wing extended blah blah blah chain....
Code:
.------------------.------------------.------------------.
| 59    59    2    |*16    4     8    |*13    136   7    |
| 7     8     3    | 2    *16    9    | 4     16    5    |
| 1     4     6    | 3    *57   *57   | 2     9     8    |
:------------------+------------------+------------------:
| 56    1567  8    | 1567 -156   2    | 9     4     3    |
| 2     3     15   | 4     9    *15   | 8     7     6    |
| 4     67    9    | 67    8     3    | 15    15    2    |
:------------------+------------------+------------------:
| 8     2     7    | 9    *35    4    | 6    *35    1    |
| 569   1569  15   | 8     1357  1567 |*35    2     4    |
| 3     156   4    | 15    2     156  | 7     8     9    |
'------------------'------------------'------------------'

basically the strong links on 5 in row 3 connect the {3,5} cell in r7c5 and the {1,5} cell in r5c6, which makes either the 1 or the 3 true. do a little extening from the 3 and get this chain to elimate the 1 in r4c5 to solve it.

(1=5)r5c6 - (5)r3c6 = (5)r3c5 - (5=3)r7c5 - (3)r7c8 = (3)r8c7 - (3=1)r1c7 - (1)r1c4 = (1)r2c5; r4c5 <> 1
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Asellus



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

PostPosted: Fri Jan 02, 2009 7:42 pm    Post subject: Reply with quote

Or, that's a 9-cell XY-Chain.

Here's a shorter ALS Chain that does the trick:
(5)r4c4|(5)r89c6 - (5=1)r5c6 - ALS[(1)r4c5=(5)r4c15] - (5)r4c4=(5)r9c4 - (5)r4c4|(5)r89c6; r4c4|r89c6<>5

Descriptively, r5c6 is <5> or <1>. If <1>, the 56 naked pair in r4 means r4c4 is not <5> so r9c4 must be <5>. Thus, r5c6 and/or r9c4 must be <5>, eliminating <5> from r4c4 and r89c6.
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cgordon



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

PostPosted: Fri Jan 02, 2009 8:25 pm    Post subject: Reply with quote

6 steps like Ted - but I started with an ER on <3> that went a long way. Then an x wing on 7; Type 4 URs on 57 and 59; an ER on 5 and the xyz wing <156>.
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storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Mon Jan 05, 2009 2:15 am    Post subject: Reply with quote

Asellus wrote:
Or, that's a 9-cell XY-Chain.

Here's a shorter ALS Chain that does the trick:
(5)r4c4|(5)r89c6 - (5=1)r5c6 - ALS[(1)r4c5=(5)r4c15] - (5)r4c4=(5)r9c4 - (5)r4c4|(5)r89c6; r4c4|r89c6<>5

Descriptively, r5c6 is <5> or <1>. If <1>, the 56 naked pair in r4 means r4c4 is not <5> so r9c4 must be <5>. Thus, r5c6 and/or r9c4 must be <5>, eliminating <5> from r4c4 and r89c6.


very nice !! Cool
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