Help me--Am I missing the obvious?

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Help me--Am I missing the obvious?

Postby A.L.Z. » Tue Jul 08, 2008 11:21 pm

What am I missing here, that I can proceed without guessing?


4XX7X1X9X
X9X3467XX
XXX9X8XXX
2471958XX
X6X48XX5X
8156X39X4
XXX5XXXXX
XX286XX1X
X8X2XXXX9
A.L.Z.
 
Posts: 2
Joined: 08 July 2008

Postby Glyn » Wed Jul 09, 2008 12:00 am

A.L.Z Here are the possibilities at the start of the puzzle.

Code: Select all
.---------------------.---------------------.---------------------.
| 4      235    368   | 7      25     1     | 2356   9      23568 |
| 15     9      18    | 3      4      6     | 7      28     1258  |
| 13567  2357   136   | 9      25     8     | 123456 2346   12356 |
:---------------------+---------------------+---------------------:
| 2      4      7     | 1      9      5     | 8      36     36    |
| 39     6      39    | 4      8      27    | 123    5      1237  |
| 8      1      5     | 6      27     3     | 9      27     4     |
:---------------------+---------------------+---------------------:
| 13679  37     13469 | 5      137    479   | 2346   234678 23678 |
| 3579   357    2     | 8      6      479   | 345    1      357   |
| 13567  8      1346  | 2      137    47    | 3456   3467   9     |
'---------------------'---------------------'---------------------'


Where can you put the 2 for Column 6? The technique is known as Hidden Singles.
Glyn
 
Posts: 357
Joined: 26 April 2007

Postby A.L.Z. » Wed Jul 09, 2008 12:32 am

Thank you Glyn....

Actually, I proceeded as follows:
You see the 2/7 pairs for Row6,Col5 and Row6,Col8?
Well, that rules out the 7 of Column 5 being in R7C5, or R9C5, so we can eliminate 7 from your list below in those cells.

This leaves 7 only one place in Column5...and this leads to some cells being solved, BUT I'M STILL STUCK!!!

We now have:

.---------------------.---------------------.---------------------.
| 4 235 368 | 7 25 1 | 2356 9 23568 |
| 15 9 18 | 3 4 6 | 7 28 1258 |
| 13567 2357 136 | 9 25 8 | 123456 2346 12356 |
:---------------------+---------------------+---------------------:
| 2 4 7 | 1 9 5 | 8 36 36 |
| 39 6 39 | 4 8 2 | 1 5 7 |
| 8 1 5 | 6 7 3 | 9 2 4 |
:---------------------+---------------------+---------------------:
| 13679 37 13469 | 5 13 479 | 2346 234678 23678 |
| 3579 357 2 | 8 6 479 | 345 1 357 |
| 13567 8 1346 | 2 13 47 | 3456 3467 9 |
'---------------------'---------------------'---------------------'


Now what??? Please help!!
A.L.Z.
 
Posts: 2
Joined: 08 July 2008

Postby udosuk » Wed Jul 09, 2008 2:37 am

A.L.Z. wrote:We now have:

Code: Select all
.---------------------.---------------------.---------------------.
| 4      235    368   | 7      25     1     | 2356   9      23568 |
| 15     9      18    | 3      4      6     | 7      28     1258  |
| 13567  2357   136   | 9      25     8     | 123456 2346   12356 |
:---------------------+---------------------+---------------------:
| 2      4      7     | 1      9      5     | 8      36     36    |
| 39     6      39    | 4      8      2     | 1      5      7     |
| 8      1      5     | 6      7      3     | 9      2      4     |
:---------------------+---------------------+---------------------:
| 13679  37     13469 | 5      13     479   | 2346   234678 23678 |
| 3579   357    2     | 8      6      479   | 345    1      357   |
| 13567  8      1346  | 2      13     47    | 3456   3467   9     |
'---------------------'---------------------'---------------------'

With the 2 in r6c8, you can eliminate all other 2s on the same column.

What then must be in r2c8? This is called a "naked single".:idea:

(Edited: Thanks Danny, corrected the typo.)
udosuk
 
Posts: 2698
Joined: 17 July 2005


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