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playr.co.uk/sudoku... extreme for august 8, 2010

 
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storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Sun Aug 08, 2010 10:36 pm    Post subject: playr.co.uk/sudoku... extreme for august 8, 2010 Reply with quote

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



after basics

Code:
+-------------------+-----------+-----------------+
| 258   4     278   | 79  1  6  | 59   3     2789 |
| 56    79    (67)  | 2   8  3  | 459  1457  179  |
| 238   2379  1     | 79  4  5  | 6    78    2789 |
+-------------------+-----------+-----------------+
| 7     23    23    | 6   5  9  | 18   18    4    |
| 9     8     4     | 1   3  2  | 7    6     5    |
| 1     6     5     | 8   7  4  | 2    9     3    |
+-------------------+-----------+-----------------+
| 248   27    9     | 5   6  18 | 3    1478  178  |
| 468   1     8-6   | 3   2  7  | 459  458   689  |
| (36)  5     (367) | 4   9  18 | 18   2     67   |
+-------------------+-----------+-----------------+
#1...xyz-wing {3,6,7}; r8c3 <> 6
--------------

Code:
+-----------------+-----------+------------------+
| 258   4     27  | 79  1  6  | 59   3      2789 |
| (56)  79    67  | 2   8  3  | 459  147-5  179  |
| 238   2379  1   | 79  4  5  | 6    78     2789 |
+-----------------+-----------+------------------+
| 7     23    23  | 6   5  9  | 18   18     4    |
| 9     8     4   | 1   3  2  | 7    6      5    |
| 1     6     5   | 8   7  4  | 2    9      3    |
+-----------------+-----------+------------------+
| 24    27    9   | 5   6  18 | 3    1478   178  |
| (46)  1     8   | 3   2  7  | 459  (45)   69   |
| 36    5     367 | 4   9  18 | 18   2      67   |
+-----------------+-----------+------------------+
#2...xy-wing {4,5,6}; r2c8 <> 5
--------------

Code:
+--------------------+-----------+-----------------+
| 58(2)  4     7(2)  | 79  1  6  | 59   3     2789 |
| 56     79    67    | 2   8  3  | 459  147   179  |
| 38(2)  2379  1     | 79  4  5  | 6    78    2789 |
+--------------------+-----------+-----------------+
| 7      23    (23)  | 6   5  9  | 18   18    4    |
| 9      8     4     | 1   3  2  | 7    6     5    |
| 1      6     5     | 8   7  4  | 2    9     3    |
+--------------------+-----------+-----------------+
| (24)   27    9     | 5   6  18 | 3    1478  178  |
| -6(4)  1     8     | 3   2  7  | 49   5     69   |
| (36)   5     67(3) | 4   9  18 | 18   2     67   |
+--------------------+-----------+-----------------+

#3...(6=3)r9c1 - (3)r9c3 = (3-2)r4c3 = (2)r1c3 - (2)r13c1 = (2-4)r7c1 = (4)r8c1; r8c1 <> 6

singles from there.
---------------


after basics there is a nice deadly pattern in the 1's and 8's



the 1 and 8 can be removed from r7c8.
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Mogulmeister



Joined: 03 May 2007
Posts: 703

PostPosted: Mon Aug 09, 2010 1:51 am    Post subject: Reply with quote

Fun puzzle Norm.

I played with creating ALS structures around the locked 23 pair at r4c23.

This one did it and I liked this because there was a double elimination needed.

Set A = {2,3,7}
Set B = {2,3,6,7,8}
x = 3 at r4c23
z = 7s at r23c2; r23c2<>7 solves.


Code:
+-------------------+-------------------+-------------------+
| 258   4     B278  | 79    1     6     | 59    3     2789  |
| 56    9-7   B67   | 2     8     3     | 459   1457  179   |
| 238  239-7  1     | 79    4     5     | 6     78    2789  |
+-------------------+-------------------+-------------------+
| 7     A23   B23   | 6     5     9     | 18    18    4     |
| 9     8     4     | 1     3     2     | 7     6     5     |
| 1     6     5     | 8     7     4     | 2     9     3     |
+-------------------+-------------------+-------------------+
| 248   A27   9     | 5     6     18    | 3     1478  178   |
| 468   1     B68   | 3     2     7     | 459   458   1689  |
| 36    5     367   | 4     9     18    | 18    2     67    |
+-------------------+-------------------+-------------------+
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Mogulmeister



Joined: 03 May 2007
Posts: 703

PostPosted: Mon Aug 09, 2010 2:13 am    Post subject: Reply with quote

Alternatively you could see the 8 in r1c3 as the fin on an xy-chain (asterisked)
If the xy-chain is true then r23c2<>7
If the fin is true then (27=8)r1c3-(8=6)r8c3-(6=7)r2c3 and r23c2<>7


Code:
+-------------------+-------------------+-------------------+
| 258   4     *27+8 | 79    1     6     | 59    3     2789  |
| 56    9-7   (6)7  | 2     8     3     | 459   1457  179   |
| 238  239-7  1     | 79    4     5     | 6     78    2789  |
+-------------------+-------------------+-------------------+
| 7     *23   *23   | 6     5     9     | 18    18    4     |
| 9     8     4     | 1     3     2     | 7     6     5     |
| 1     6     5     | 8     7     4     | 2     9     3     |
+-------------------+-------------------+-------------------+
| 248   *27   9     | 5     6     18    | 3     1478  178   |
| 468   1     6(8)  | 3     2     7     | 459   458   1689  |
| 36    5     367   | 4     9     18    | 18    2     67    |
+-------------------+-------------------+-------------------+
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peterj



Joined: 26 Mar 2010
Posts: 974
Location: London, UK

PostPosted: Mon Aug 09, 2010 12:38 pm    Post subject: Reply with quote

Roughly in the same area is this short discontinuous loop..

Code:
As an AIC, (2=3)r4c2 - r4c3=(3-7)r9c3=r7c2 ; r7c2<>2


Mm, you almost-xy-chain is also an almost w-wing!
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Mogulmeister



Joined: 03 May 2007
Posts: 703

PostPosted: Mon Aug 09, 2010 1:00 pm    Post subject: Reply with quote

I know, I nearly went "x-ey,y-ey,wing-ey thing-ey" ! They're all just AICs - I think I'm losing my religion.
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Luke451



Joined: 20 Apr 2008
Posts: 310
Location: Southern Northern California

PostPosted: Tue Aug 10, 2010 5:17 am    Post subject: Reply with quote

Mogulmeister wrote:
I know, I nearly went "x-ey,y-ey,wing-ey thing-ey" ! They're all just AICs - I think I'm losing my religion.

You've been proselytized by the dark side Twisted Evil.
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Mogulmeister



Joined: 03 May 2007
Posts: 703

PostPosted: Tue Aug 10, 2010 7:28 am    Post subject: Reply with quote

Yes-get behind me Satan!
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