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diabolical - daily telegraph Nov 23

 
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storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Sat Nov 24, 2007 6:37 am    Post subject: diabolical - daily telegraph Nov 23 Reply with quote

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


http://www.sudoku.telegraph.co.uk/
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nataraj



Joined: 03 Aug 2007
Posts: 1048
Location: near Vienna, Austria

PostPosted: Sat Nov 24, 2007 2:10 pm    Post subject: Reply with quote

after basics:

Code:

+--------------------------+--------------------------+--------------------------+
| 4       3       5        | 89      6       89       | 1       7       2        |
| 1       8       7        | 5       2       34       | 9       36      346      |
| 9       2       6        | 37      47      1        | 5       8       34       |
+--------------------------+--------------------------+--------------------------+
| 2       57      9        | 1       8       6        | 4       35      37       |
| 67      15      4        | 279     3       279      | 78      15      6789     |
| 3       167     8        | 4       79      5        | 2       16      679      |
+--------------------------+--------------------------+--------------------------+
| 67      9       2        | 678     5       78       | 3       4       1        |
| 5       46      3        | 26      1       24       | 78      9       78       |
| 8       47      1        | 379     479     3479     | 6       2       5        |
+--------------------------+--------------------------+--------------------------+


a useless xy-wing: 74-43-37 pivot r3c9
that can be continued into an xy-chain

'73'(49)='34'(39)='47'(35)='73'(34)='34'(26)='42'(86)='26'(84)='64'(82)='47'(92)='76'(71)='67'(51)

removes "7"s from r4c2 r5c7.

Later on
Code:

+--------------------------+--------------------------+--------------------------+
| 4       3       5        | 89      6       89       | 1       7       2        |
| 1       8       7        | 5       2       34       | 9       6       34       |
| 9       2       6        | 37      47      1        | 5       8       34       |
+--------------------------+--------------------------+--------------------------+
| 2       5       9        | 1       8       6        | 4       3       7        |
| 67      1       4        | 279     3       279      | 8       5       69       |
| 3       67      8        | 4       79      5        | 2       1       69       |
+--------------------------+--------------------------+--------------------------+
| 67      9       2        | 678     5       78       | 3       4       1        |
| 5       46      3        | 26      1       24       | 7       9       8        |
| 8       47      1        | 379     479     3479     | 6       2       5        |
+--------------------------+--------------------------+--------------------------+


a w-wing (47)
'47'(35)='79'(65)='96'(69)='67'(62)='74'(92)

finally solved the puzzle

nice!
thx norm!
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Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA

PostPosted: Sat Nov 24, 2007 4:36 pm    Post subject: Reply with quote

How do these puzzles relate to the diabolicals that appear on Friday and Sunday at sudoku.org.uk? I notice at this site on the printable version the sudoku.org site is mentioned, but the diabolical I have for November 23 is different than this one.
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storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Sat Nov 24, 2007 6:11 pm    Post subject: Reply with quote

Marty R. wrote:
How do these puzzles relate to the diabolicals that appear on Friday and Sunday at sudoku.org.uk? I notice at this site on the printable version the sudoku.org site is mentioned, but the diabolical I have for November 23 is different than this one.


I noticed last week that the sudoku.org.uk site had changed its address. And I notice that some of the links were giving directions to the new site and some weren't. last evening, I tried clicking on the newspaper link, and I didn't get anything, I got a blank grid.
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ravel



Joined: 21 Apr 2006
Posts: 536

PostPosted: Sun Nov 25, 2007 11:34 am    Post subject: Reply with quote

nataraj wrote:
a useless xy-wing: 74-43-37 pivot r3c9
that can be continued into an xy-chain
Interestingly i also noticed this xy-wing and tried to "transport" the 7 in r3c5 (btw how did you get the 5 in r8c1 ?) I used the UR 78 to get here:
Code:
 *-----------------------------------------------------------*
 | 4     3     5     | 89    6     89    | 1     7     2     |
 | 1     8     7     | 5     2     34    | 9     36    346   |
 | 9     2     6     | 37    47    1     | 5     8     34    |
 |-------------------+-------------------+-------------------|
 | 2     57    9     | 1     8     6     | 4     35    37    |
 |A567   1567  4     |B279   3    B279   | 8     156   69    |
 | 3     167   8     | 4    B79    5     | 2     16    679   |
 |-------------------+-------------------+-------------------|
 | 67    9     2     | 678   5     78    | 3     4     1     |
 | 56    456   3     | 26    1     24    | 7     9     8     |
 | 8    A47    1     | 379  A479   3479  | 6     2     5     |
 *-----------------------------------------------------------*
With the strong link for 4 in c5 i got
r3c5=7 => r9c5=4 => r9c2=7 (which would exclude 7 from r4c2) => r5c1=7
But i also saw
r3c5=7 => r6c5<>7 => r5c46=7 => r5c1<>7
So i found a contradiction without really searching for one. Then r3c5 must be 4 and the puzzle is solved with an xy-wing.
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re'born



Joined: 28 Oct 2007
Posts: 80

PostPosted: Sun Nov 25, 2007 1:05 pm    Post subject: Reply with quote

Well, since somebody mentioned transport, here is an overly elaborate solution using transport. After singles:
Code:
 *-----------------------------------------------------------*
 | 4     3     5     | 89    6     89    | 1     7     2     |
 | 1     8     7     | 5     2     34&   | 9     36    346   |
 | 9     2     6     | 37*   47    1     | 5     8     34    |
 |-------------------+-------------------+-------------------|
 | 2     57    9     | 1     8     6     | 4     35    37    |
 | 67    15    4     | 29-7  3     279*  | 78    15    6789  |
 | 3     167   8     | 4     79*   5     | 2     16    679   |
 |-------------------+-------------------+-------------------|
 | 67    9     2     | 678   5     78    | 3     4     1     |
 | 5     46    3     | 26    1     24&   | 78    9     78    |
 | 8     47    1     | 379   479   3479  | 6     2     5     |
 *-----------------------------------------------------------*

I find an "xyz-chain", which implies that one of the *'d cells is a 7. This immediately eliminates 7 from r5c4. Now we transport all three cells:
Code:
 *-----------------------------------------------------------*
 | 4     3     5     | 89    6     89    | 1     7     2     |
 | 1     8     7     | 5     2     34    | 9     36    346   |
 | 9     2     6     | 37A  4AB7ab 1     | 5     8     34    |
 |-------------------+-------------------+-------------------|
 | 2     57    9     | 1     8     6     | 4     35    37    |
 | 67c   15    4     | 29    3     27C9  | 78    15    6789  |
 | 3     167   8     | 4     7B9   5     | 2     16    679   |
 |-------------------+-------------------+-------------------|
 | 67C   9     2     | 678   5     78    | 3     4     1     |
 | 5     46    3     | 26    1     24    | 78    9     78    |
 | 8     4C7c  1     | 379   79-4  3479  | 6     2     5     |
 *-----------------------------------------------------------*

(7)r6c5 and (7)r3c4 are both transported to (7)r3c5, while (7)r5c6 is transported to (4)r9c2 (note that the letters above are not meant to represent conjugates, only to give the reader a quick view of the transport). So now we can eliminate 4 from r9c5. This reduces the puzzle to the following BUG+2:
Code:
*--------------------------------------------------*
 | 4    3    5    | 89   6    89   | 1    7    2    |
 | 1    8    7    | 5    2    3    | 9    6    4    |
 | 9    2    6    | 7    4    1    | 5    8    3    |
 |----------------+----------------+----------------|
 | 2    5    9    | 1    8    6    | 4    3    7    |
 | 67   1    4    | 29   3    27+9 | 8    5    69   |
 | 3    67   8    | 4    79   5    | 2    1    69   |
 |----------------+----------------+----------------|
 | 67   9    2    | 68   5    78   | 3    4    1    |
 | 5    46   3    | 26   1    24   | 7    9    8    |
 | 8    47   1    | 3    79   49+7 | 6    2    5    |
 *--------------------------------------------------*

from which we deduce r5c6<>7 (as well r9c6<>9), solving the puzzle.
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nataraj



Joined: 03 Aug 2007
Posts: 1048
Location: near Vienna, Austria

PostPosted: Sun Nov 25, 2007 1:15 pm    Post subject: Reply with quote

ravel wrote:
btw how did you get the 5 in r8c1 ?)


now that you mention it ... hm. I threw out all sheets from last week this morning. Luckily they're still in the waste-paper-bin (thank god for waste separation).

Seems that before the xy-chain on the right side there was another xy-wing-turned-xy-chain (from that same "useless xy-wing pivot r3c9) removes "5"s over on the left side. I spotted this one fairly easily so it didn't make it into my post. But rightly should have been there:


'57'(42)='73'(49)='34'(39)='47'(35)='73'(34)='34'(26)='42'(86)='26'(84)='65'(81)

removes 5 from r8c2 r5c1.


edit: pls excuse the notation. = in this case is not supposed to imply strong links, just the way the chain works.
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