AU tough January 29, 2013

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AU tough January 29, 2013

Postby ArkieTech » Tue Jan 29, 2013 6:52 am

Code: Select all
 *-----------*
 |...|..4|...|
 |.7.|.69|.1.|
 |...|5..|4.8|
 |---+---+---|
 |5..|...|32.|
 |...|.1.|...|
 |.82|...|..5|
 |---+---+---|
 |6.4|..3|...|
 |.1.|95.|.7.|
 |...|4..|...|
 *-----------*


Play/Print this puzzle online
dan
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Re: AU tough January 29, 2013

Postby Leren » Tue Jan 29, 2013 7:54 am

Code: Select all
*--------------------------------------------------------------------------------*
| 289     2569    5689     | 1       3       4        | 5679    569     679      |
| 4       7       35       | 8       6       9        | 25      1       23       |
| 139     369     1369     | 5       7       2        | 4       369     8        |
|--------------------------+--------------------------+--------------------------|
| 5      b49      17       | 6       49      8        | 3       2       17       |
|a379    a3469   a3679     | 2       1       5        |a789     489    a79       |
| 19      8       2        | 3       49      7        | 169     469     5        |
|--------------------------+--------------------------+--------------------------|
| 6      c259     4        | 7       28      3        | 12589   589     129      |
|c238     1      c38       | 9       5       6        | 2-8     7       4        |
| 2789   c259     5789     | 4       28      1        | 25689   35689   2369     |
*--------------------------------------------------------------------------------*


als xy-wing: (8=4) r5c12379 - (4=9) r4c2 - (9=8) r79c2,r8c13 => r8c7 <> 8; stte

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Re: AU tough January 29, 2013

Postby Marty R. » Wed Jan 30, 2013 12:17 am

Not a solution I'm particularly proud of, but r4c2=9=>contradiction=>r4c2<>9.

R4c2=9=>r5c1=3
R4c2=9=>r8c1=3 via the 25 pair in r79c2 which leads to the four-cell XY-Loop.
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Location: Rochester, New York, USA

Re: AU tough January 29, 2013

Postby JC Van Hay » Wed Jan 30, 2013 9:53 am

Marty R. wrote:Not a solution I'm particularly proud of, but r4c2=9=>contradiction=>r4c2<>9.

R4c2=9=>r5c1=3
R4c2=9=>r8c1=3 via the 25 pair in r79c2 which leads to the four-cell XY-Loop.
I don't understand why ! On the contrary, I like it ;) It explains very well what is going on in the puzzle and how to "easily(?)" find useful chains and patterns !
To wit, you can restate your solution as :

  1. There is an XY-Loop in r28c37 removing 8r8c1 :=> r8c1=23.
  2. r4c2=9->NP(25)r79c2 and NT(137)B6-> r8c1 empty or, equivalently,
    r8c1=2->NP(59)r79c2, while r8c2=3->NT(179)B6; the pincers 9r79c2 and 9r56c1 eliminate 9r9c1.r45c2
In Eureka! :
#1. Chain[4] : XY-Loop : (8=3)r8c3-(3=5)r2c3-(5=2)r2c7-(2=8)r8c7 @ :=> -3r35c3,-2r79c7,-8r8c1
#2. Chain[6] : ALS-XY Wing (Death Blossom, here) : (9=52)r79c2-(2=3)r8c1-(3=179)r56c1.r4c3 :=> -9r9c1.r45c2
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Re: AU tough January 29, 2013

Postby SudoQ » Wed Jan 30, 2013 4:23 pm

Bi cells only:
Code: Select all
|------------------|----------|--------------------|
|9/8-2  2569  569/8| 1  3   4 | 5679   569    679  |
| 4     7     5/3  | 8  6   9 | 5/2    1     (23)  |
| 139   369   1369 | 5  7   2 | 4      369    8    |
|------------------|----------|--------------------|
| 5     49    17   | 6  49  8 | 3      2      17   |
| 379   3469  3679 | 2  1   5 | 789    489    79   |
| 19    8     2    | 3  49  7 | 169    469    5    |
|------------------|----------|--------------------|
| 6     259   4    | 7  28  3 | 12589  589    129  |
| 38/2  1    (38)  | 9  5   6 | 8/2    7      4    |
| 2789  259   5789 | 4  28  1 | 25689  35689  2369 |
|------------------|----------|--------------------|
/SudoQ
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Re: AU tough January 29, 2013

Postby Marty R. » Wed Jan 30, 2013 4:57 pm

I don't understand why ! On the contrary, I like it ;) It explains very well what is going on in the puzzle and how to "easily(?)" find useful chains and patterns !


Thanks. It's just something I didn't see, but just stumbled upon while trying a chain and it had a trial-and-error feel to it.
Marty R.
 
Posts: 1420
Joined: 23 October 2012
Location: Rochester, New York, USA


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