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Krampus Edition - "Nice" #1

 
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peterj



Joined: 26 Mar 2010
Posts: 974
Location: London, UK
PostPosted: Wed Dec 08, 2010 6:07 pm    Post subject: Krampus Edition - "Nice" #1 Reply with quote
Code:
 *-----------*
 |...|2..|..7|
 |.2.|.15|..4|
 |..9|.84|...|
 |---+---+---|
 |34.|...|1..|
 |.6.|8.1|.4.|
 |..2|...|.36|
 |---+---+---|
 |...|59.|6..|
 |7..|12.|.9.|
 |2..|..6|...|
 *-----------*

Code:
000200007020015004009084000340000100060801040002000036000590600700120090200006000

(c) Helmut Saueregger
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Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
PostPosted: Wed Dec 08, 2010 11:26 pm    Post subject: Reply with quote
Code:

+-------+-------+-------+
| . . . | 2 . . | . . 7 |
| . 2 . | . 1 5 | . . 4 |
| . . 9 | . 8 4 | . . . |
+-------+-------+-------+
| 3 4 . | . . . | 1 . . |
| . 6 . | 8 . 1 | . 4 . |
| . . 2 | . . . | . 3 6 |
+-------+-------+-------+
| . . . | 5 9 . | 6 . . |
| 7 . . | 1 2 . | . 9 . |
| 2 . . | . . 6 | . . . |
+-------+-------+-------+

Play this puzzle online at the Daily Sudoku site

M-Wing (79), flightless, with transport; r6c457<>7
ERs (8,8,7); the 7 was the key, r4c8<>7
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tlanglet



Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
PostPosted: Thu Dec 09, 2010 3:52 pm    Post subject: Reply with quote
Flightless xy-wing 3-79 with both pincers transported on 7: (7)r6c2=(7)r3c2-(7=3)r3c4-(3=9)r1c6-(9=7)r6c6*-r7c6=r7c8-r4c8=(7)r5c7; r6c57, r5c3<>7

Ted
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daj95376



Joined: 23 Aug 2008
Posts: 3854
PostPosted: Thu Dec 09, 2010 7:59 pm    Post subject: Reply with quote
Ted, an impressive network.
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Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
PostPosted: Fri Dec 10, 2010 1:19 am    Post subject: Reply with quote
daj95376 wrote:
Ted, an impressive network.

Danny, how would you define "network"?
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daj95376



Joined: 23 Aug 2008
Posts: 3854
PostPosted: Fri Dec 10, 2010 1:57 am    Post subject: Reply with quote
Marty R. wrote:
daj95376 wrote:
Ted, an impressive network.

Danny, how would you define "network"?

Code:
(7)r6c2=(7)r3c2-(7=3)r3c4-(3=9)r1c6-(9=7)r6c6*-r7c6=r7c8-r4c8=(7)r5c7; r6c57, r5c3<>7
_____________________________________________________________________________________

When Ted gets to this part of his chain:

(7)r6c2=...-(9=7)r6c6*...

he's able to deduce r6c57<>7.

Without remembering the elimination r6c7<>7, this part of his chain:

r4c8=(7)r5c7

fails to materialize and produce the critical elimination r5c3<>7.

Network: When elimination(s) created earlier in the chain must be remembered to allow a step later in the chain.

Code:
 +-----------------------------------------------------------------------+
 |  1458   1358   13458  |  2      6      39     |  3589   158    7      |
 |  68     2      37     |  379    1      5      |  39     68     4      |
 |  156    1357   9      |  37     8      4      |  235    1256   1235   |
 |-----------------------+-----------------------+-----------------------|
 |  3      4      578    |  6      57     2      |  1      578    9      |
 |  9      6      57     |  8      3      1      |  257    4      25     |
 |  158    1578   2      |  49     457    79     |  578    3      6      |
 |-----------------------+-----------------------+-----------------------|
 |  148    138    1348   |  5      9      378    |  6      127    1238   |
 |  7      358    6      |  1      2      38     |  4      9      358    |
 |  2      9      1358   |  34     47     6      |  357    157    1358   |
 +-----------------------------------------------------------------------+
 # 87 eliminations remain

Two step alternative:

Code:
(7)r6c2=(7)r3c2-(7=3)r3c4-(3=9)r1c6-(9=7)r6c6  =>  r6c57<>7

turbot fish:  (7)r4c5 = r6c6 - r7c6 = (7)r7c8  =>  r4c8<>7

Peter: I deliberately skipped making the first step into a loop. Very Happy

Last edited by daj95376 on Fri Dec 10, 2010 2:33 am; edited 1 time in total
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tlanglet



Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
PostPosted: Fri Dec 10, 2010 2:28 am    Post subject: Reply with quote
daj95376 wrote:
Ted, an impressive network.


Danny,

Thanks very much foryour comment. I have been greatly distracted recently by supporting a yearly volunteer activity and have not had the time/opportunity to play sudoku regularly, so it was nice to readily find this chain. It actually started as a flightless xy-wing 3-79 with vertex in r1c6 and just grew by extending both pincers.

I have recently gotten into the habit of trying to extend all pincers associated with any pattern. As with any other move, transporting pincers sometimes is useless but sometimes they pay of handsomely as in this case. In general I believe that the small additional effort is worth the results.

Ted
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