The New Sudoku Players' Forum

[nicktheconfused]

I'm stuck at this point. Can anyone help me?

. 7 . l . 5 4 l 8 . .
. 4 . l 7 . . l 3 6 .
. . 8 l . . . l . . 4
---------------------
7 . 4 l . . 1 l . . 6
9 . 2 l . . . l . . 8
5 . . l 2 . . l 4 . .
---------------------
. . . l . . . l 1 . .
. 2 6 l . . 9 l . 8 .
. . 7 l 3 2 . l 6 4 .

I can see some "triple pairs" but don't know how to work them. Also, could someone explain some of the more advanced tricks for me such as an "x-wing".

Thanks

Nick
Thanks

[MCC]

Nick
It would help if you posted your candidate list so we know how far you've gone.
In the mean time:

Look to c8, a naked pair leads to some eliminations.
Then look at box 3, you can now place two numbers.

MCC

[Animator]

Please, try to be more informative when posting a question...

You did not include the source of the puzzle nor the level of difficuty...

You did not include a candidate list so that we have no way of knowing what techniques you successfully used...

For example, did you see the hidden and naked pair in column 8? If not then you shouldn't be thinking about triples.

Also, an X-Wing is not required for this puzzle.
If you would like to discuss X-Wings in general and/or read up on them then you should check the 'Advanced solving techniques' section. ( http://forum.enjoysudoku.com/viewforum.php?f=3 )
If on the other hand you have a particular puzzle in mind or are stuck on a puzzle then you should post it in here.

But before you start with X-wings you should fully understands pairs and triples. (and perhaps quads aswell.)

Update: clarified the note about the X-Wing technique

[nicktheconfused]

Nick
It would help if you posted your candidate list so we know how far you've gone.
In the mean time:

Look to c8, a naked pair leads to some eliminations.
Then look at box 3, you can now place two numbers.

MCC

Thank your for your help with this. I'm new to this so I'm not sure what a candidate list is.

Would you mind spelling out where the naked pair are and how this leads to a solution?

Thanks

Nick

[nicktheconfused]

Please, try to be more informative when posting a question...

You did not include the source of the puzzle nor the level of difficuty...

You did not include a candidate list so that we have no way of knowing what techniques you successfully used...

For example, did you see the hidden and naked pair in column 8? If not then you shouldn't be thinking about triples.

Also, an X-Wing is not required for this puzzle. If you would like to discuss X-Wings and/or read up on them then you should check the 'Advanced solving techniques' section. ( http://forum.enjoysudoku.com/viewforum.php?f=3 )

But before you start with X-wings you should fully understands pairs and triples. (and perhaps quads aswell.)

Than you to this. I'm new to this so didn't understand about "candidate list" you mention. I'll look into it.

Would you mind spelling out how the naked and hidden pair technique helps me? Where are they?

thanks

Nick

[Animator]

A candidate list (also known as pencilmarks) is a list of what numbers can go in what cells.

The naked pair and the hidden pair is in column 7, not column 8.

For your grid this is:

Code: Select all

-------------------------------------------------------------------
| 1236   7       139 | 169    5       4    | 8      129     129   |
| 12     4       159 | 7      189     28   | 3      6       1259  |
| 1236   13569   8   | 169    1369    236  | 2579   12579   4     |
|--------------------+--------------------------------------------|
| 7      38      4   | 589    389     1    | 259    2359    6     |
| 9      136     2   | 456    3467    3567 | 57     1357    8     |
| 5      1368    13  | 2      36789   3678 | 4      1379    1379  |
|--------------------+---------------------+----------------------|
| 348    3589    359 | 4568   4678    5678 | 1      23579   23579 |
| 134    2       6   | 145    147     9    | 57     8       357   |
| 18     1589    7   | 3      2       58   | 6      4       59    |
-------------------------------------------------------------------


Now let's look at column 7 closely: I see a naked pair of 5 and 7 and a hidden pair of 2 and 9.

Both of these should lead you to the conclusion that 5 nor 7 can go in r3c7.
This then leaves only one candidate-cell for the number 7 in box 3. Namely r3c8.
Now when that is done you see that there is only candidate-cell for the number 5 in box 3. (r2c9)

[Cec]

"..Would you mind spelling out how the naked and hidden pair technique helps me? Where are they?.."

Hi Nick,
I get the impression you are also seeking explanations as to how these and other "basic" solving techniques work. If this is the case you could look at the following highly recommended sites:
http://www.angusj.com/sudoku/hints.php
http://www.simes.clara.co.uk/programs/sudokutechniques.htm

Cec

[MCC]

Oops.Sorry Nick. As Animator as pointed out I should have said column 7 not column 8.

MCC

[QBasicMac]

I'm stuck at this point. Can anyone help me?

Here are the original pencilmarks for your puzzle:

Code: Select all

+------------------+-------------------+--------------------+
| 1236  7      139 | 169   5      4    | 8     129    129   |
| 12    4      159 | 7     189    28   | 3     6      1259  |
| 1236  13569  8   | 169   1369   236  | 2579  12579  4     |
+------------------+-------------------+--------------------+
| 7     38     4   | 589   389    1    | 259   2359   6     |
| 9     136    2   | 456   3467   3567 | 57    1357   8     |
| 5     1368   13  | 2     36789  3678 | 4     1379   1379  |
+------------------+-------------------+--------------------+
| 348   3589   359 | 4568  4678   5678 | 1     23579  23579 |
| 134   2      6   | 145   147    9    | 57    8      357   |
| 18    1589   7   | 3     2      58   | 6     4      59    |
+------------------+-------------------+--------------------+


You can proceed as follows:
> Locked candidate 3 in box 2
Translation: Look in the second box. Note that all 3's in that box are in row 3. That means that the 3 that you eventually place in box 2 MUST go on row 3. Thus all other 3's in row 3 can be erased. Erase 3 from r3c1 and r3c2 (r3c12).

> Locked candidate 6 in box 4
Same, except for column. Erase 6 from r3c2.

> Locked candidate 8 in box 4

> Locked candidate 1 in box 8

> Naked pair 57 in col 7
Translation: As r5c7 and r8c7 both contain 57, any 5 or 7 to be placed in col 7 MUST be in one of those two cells. Erase 5 and 7 from r3c7. Erase 5 from r4c7.

Here is your candidate list (also called "pencilmarks") at this point:

Code: Select all

+-----------------+-------------------+------------------+
| 1236  7     139 | 169   5      4    | 8   129    129   |
| 12    4     159 | 7     189    28   | 3   6      1259  |
| 126   159   8   | 169   1369   236  | 29  12579  4     |
+-----------------+-------------------+------------------+
| 7     38    4   | 589   389    1    | 29  2359   6     |
| 9     136   2   | 456   3467   3567 | 57  1357   8     |
| 5     1368  13  | 2     36789  3678 | 4   1379   1379  |
+-----------------+-------------------+------------------+
| 348   359   359 | 4568  4678   5678 | 1   23579  23579 |
| 34    2     6   | 145   147    9    | 57  8      357   |
| 18    159   7   | 3     2      58   | 6   4      59    |
+-----------------+-------------------+------------------+


> Hidden single 7 in row 3
Translation: Note that r3 contains only one pencilmark 7 (in r3c8). Enter 7 as a solution there. That erases all other 7's in that box, row and column.

> Hidden single 5 in box 3
You now see that box 3 contains only 1 5. Place it and erase corresponding pencilmarks. Got it?

And so on. Here are some next moves...
Hidden single 5 in row 3
Hidden single 5 in col 3
Hidden single 5 in box 9
Hidden single 5 in row 9
r5c7 = 7
r9c9 = 9
r9c2 = 1
r9c1 = 8
Hidden single 1 in row 5
Hidden single 1 in row 6
Hidden single 9 in row 7
r2c3 = 9

Mac