AU tough December 3, 2012

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AU tough December 3, 2012

Postby ArkieTech » Mon Dec 03, 2012 7:01 am

Code: Select all
 *-----------*
 |..3|.6.|8..|
 |6..|5..|.7.|
 |.4.|...|..9|
 |---+---+---|
 |..2|.1.|...|
 |5..|...|..4|
 |...|.8.|6..|
 |---+---+---|
 |7..|...|.4.|
 |.1.|..2|..5|
 |..8|.5.|1..|
 *-----------*


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dan
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Re: AU tough December 3, 2012

Postby storm_norm22 » Mon Dec 03, 2012 9:25 am

Code: Select all
+-----------------------+---------------------+----------------------+
| 12-9  57       3      | 12479  6     1479   | 8     125       12   |
| 6     (89)     (19)   | 5      23-9  138-9  | 4     7         123  |
| 128   4        57     | 12378  237   1378   | 235   6         9    |
+-----------------------+---------------------+----------------------+
| 389   3679-8   2      | 34679  1     345679 | 3579  3589      378  |
| 5     3679(8)  679(1) | 23679  2379  3679   | 2379  -239(18)  4    |
| 139   379      4      | 2379   8     3579   | 6     12359     1237 |
+-----------------------+---------------------+----------------------+
| 7     23569    569    | 13689  39    13689  | 239   4         2368 |
| 39    1        69     | 36789  4     2      | 379   389       5    |
| 4     2369     8      | 3679   5     3679   | 1     239       2367 |
+-----------------------+---------------------+----------------------+


Loop - (9=1)r2c3 - (1)r5c3 = (1-8)r5c8 = (8)r5c2 - (8=9)r2c2;
r1c1 <> 9
r2c56 <> 9
r4c2 <> 8
r5c8 <> 2,3,9
Norm
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Re: AU tough December 3, 2012

Postby ArkieTech » Mon Dec 03, 2012 12:22 pm

storm_norm22 wrote:Loop - (9=1)r2c3 - (1)r5c3 = (1-8)r5c8 = (8)r5c2 - (8=9)r2c2;
r1c1 <> 9
r2c56 <> 9
r4c2 <> 8
r5c8 <> 2,3,9


I like it :D

Code: Select all
 *-----------------------------------------------------------------------------*
 | 12-9    57      3       | 12479   6       1479    | 8       125     12      |
 | 6      a89     c19      | 5       23-9    138-9   | 4       7       123     |
 | 128     4       57      | 12378   237     1378    | 235     6       9       |
 |-------------------------+-------------------------+-------------------------|
 | 389     36789   2       | 34679   1       345679  | 3579    3589    378     |
 | 5      b36789  b1679    |b23679  b2379   b3679    |b2379    12389   4       |
 | 139     379     4       | 2379    8       3579    | 6       12359   1237    |
 |-------------------------+-------------------------+-------------------------|
 | 7       23569   569     | 13689   39      13689   | 239     4       2368    |
 | 39      1       69      | 36789   4       2       | 379     389     5       |
 | 4       2369    8       | 3679    5       3679    | 1       239     2367    |
 *-----------------------------------------------------------------------------*
als xy-wing
(9=8)r2c2-(8r2c2=1r2c3)r5c234567-(1=9)r2c3 => -9r2c56,r1c1; lclste
dan
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Re: AU tough December 3, 2012

Postby Marty R. » Mon Dec 03, 2012 8:33 pm

Code: Select all
+----------------+-------------------+-----------------+
| 129 57    3    | 12479 6    1479   | 8    125   12   |
| 6   89    19   | 5     239  1389   | 4    7     123  |
| 128 4     57   | 12378 237  1378   | 235  6     9    |
+----------------+-------------------+-----------------+
| 389 36789 2    | 34679 1    345679 | 3579 3589  378  |
| 5   36789 1679 | 23679 2379 3679   | 2379 12389 4    |
| 139 379   4    | 2379  8    3579   | 6    12359 1237 |
+----------------+-------------------+-----------------+
| 7   23569 569  | 13689 39   13689  | 239  4     2368 |
| 39  1     69   | 36789 4    2      | 379  389   5    |
| 4   2369  8    | 3679  5    3679   | 1    239   2367 |
+----------------+-------------------+-----------------+

Play this puzzle online at the Daily Sudoku site

I haven't been able to do anything with this puzzle, but I'll post one move to practice notation, which looks pretty clumsy.

A 9 in r8c1 proves 9 in r1c1.

(3=9)r8c1-(69=5)r78c3-r3c3=r1c2-(5=12)r1c89-(12=9)r1c1=>r8c1<>9
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Re: AU tough December 3, 2012

Postby Leren » Tue Dec 04, 2012 3:26 am

My take on this puzzle is that the arrangement of 1's and 8's in Row 5 reminds me of the Purple Cow construction I've seen elsewhere.

Taking Norm's and Dan's approaches together I'd describe Norm's move as a Purple Cow XY Wing Loop :D

Even when considered as an ALS XY Wing Dan's move is also a loop and justifies r4c2 <8>.

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Re: AU tough December 3, 2012

Postby tlanglet » Wed Dec 05, 2012 3:13 am

Another solution is an ANP().

ANP(39=1)r86c1-r5c3=(1-8)r5c8=r5c2-(8=9)r2c2 => r1c1<>9
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