Missin logic in this hard/medium Sudoku from Su-Doku Time?

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Missin logic in this hard/medium Sudoku from Su-Doku Time?

Postby Quitschi » Thu Sep 26, 2013 8:44 pm

Hey all of out there.


I tried this Sudoku from Su-Doku Time and got stuck. (Original grid on the left, the point I got to on the right)
An online solver I found (http://www.sudoku-lobby.de/sudoku-loesung/sudoku.sudoku?IDraster=482745) suggests to fill in a 7 in the first row fourth cell by the logic of trial and error - I don't like that.
So is there some logic solving method I am missing or is it only possible to go on by trial and error?

Sudoku 26.9.13.jpg
Sudoku 26.9.13.jpg (74.87 KiB) Viewed 460 times


Thanks in advance for any comments and many greetings.

Q
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Re: Missin logic in this hard/medium Sudoku from Su-Doku Tim

Postby JasonLion » Thu Sep 26, 2013 10:31 pm

You can continue from there using locked candidates, and naked pairs/triples. There is no need for either guessing or trial and error.
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Re: Missin logic in this hard/medium Sudoku from Su-Doku Tim

Postby ArkieTech » Sat Sep 28, 2013 9:00 pm

Code: Select all
 *-----------*
 |...|...|..6|
 |..2|.8.|.3.|
 |..9|6.4|...|
 |---+---+---|
 |...|.5.|68.|
 |..5|.71|2..|
 |14.|...|..7|
 |---+---+---|
 |3..|..7|...|
 |71.|..8|...|
 |9..|...|.5.|
 *-----------*
 *-----------------------------------------------------------*
 | 458   378   1     | 237   23    59    | 489   27    6     |
 | 456   67    2     | 17    8     59    | 149   3     459   |
 | 58    378   9     | 6     123   4     | 18    127   258   |
 |-------------------+-------------------+-------------------|
 | 2     9     7     | 4     5     3     | 6     8     1     |
 | 68    68    5     | 9     7     1     | 2     4     3     |
 | 1     4     3     | 8     6     2     | 5     9     7     |
 |-------------------+-------------------+-------------------|
 | 3     5     468   | 12    1249  7     | 1489  126   2489  |
 | 7     1     46    | 5     249   8     | 3     26    249   |
 | 9     2     48    | 13    134   6     | 7     5     48    |
 *-----------------------------------------------------------*
In row 9 there is a pair of 48 (all other cells in r9 cannot contain a 4 or 8
r9c5 can drop the 4 making it a 13
This makes a 13 pair in block 8 (middle bottom).
The 1 can be removed from r7c4 allowing it to be set as a 2

Now can you find a triple in row 1?
dan
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Postby Pat » Sun Sep 29, 2013 10:27 am

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

it's a 2-move puzzle

    b2 "naked" duo --> r1 trio
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