The New Sudoku Players' Forum

[throbdude]

I have no idea other than just guessing.
All I need to do is know just one to really get the rest of the grid:

[tso]

You've got a naked pair of [56] in row 8.

[throbdude]

Whoops!

Missed that lonely "9" in row 8 .... guess I needed to step away from it for awhile.

Thanks!

[kf-ryan]

First, a very nicely presented grid. Thanks.
Second, another way to see through the puzzle: In the lower right box the top row contains 69 - 59; the middle row contains 56. Thus a 9 has to be in the top row, and that eliminates a 9 from the top row of the bottem left box. I find this approach quite helpful in difficult places in evil puzzles.

Ken

[QBasicMac]

First, a very nicely presented grid. Thanks.

I, on the other hand, pray I never see another puzzle posted like that.

Code: Select all

+------------+---------+------------+
| 59  69  56 | 4  7  8 | 2   1   3  |
| 8   3   2  | 1  6  5 | 7   4   9  |
| 4   7   1  | 9  2  3 | 5   6   8  |
+------------+---------+------------+
| 6   4   3  | 7  5  9 | 1   8   2  |
| 7   1   8  | 2  3  4 | 69  59  56 |
| 2   5   9  | 6  8  1 | 4   3   7  |
+------------+---------+------------+
| 59  8   7  | 3  1  2 | 69  59  4  |
| 1   69  56 | 8  4  7 | 3   2   56 |
| 3   2   4  | 5  9  6 | 8   7   1  |
+------------+---------+------------+


is is easier to paste into scratchpads.

Although, true, this one can be easily solved from just staring at the display. So the use of the colorful image is fine in this exact thread. Although I wonder if images stay around as long as threads do. I can imagine the day this thread has a blank image.

Well, my display will still be there

Mac

[Crazy Girl]

First, a very nicely presented grid. Thanks.
Second, another way to see through the puzzle: In the lower right box the top row contains 69 - 59; the middle row contains 56. Thus a 9 has to be in the top row, and that eliminates a 9 from the top row of the bottem left box. I find this approach quite helpful in difficult places in evil puzzles.

Ken

This technique is referred to as Locked Candidates, where a candidate ( in this case 9) is locked to a certain position in this case Block 9 Row 7, so 9 can be eliminated from the rest of Row 7 not in Block 9.

For more techniques check out
http://www.angusj.com/sudoku/hints.php
http://www.simes.clara.co.uk/programs/sudokutechniques.htm

[throbdude]

Here is another puzzle that I have no clue as to what to do next.

I imagine I have to use one of those clever X or XY tricks, but really don't know where to look right now.

Code: Select all

7    3     258 | 268    258  9    | 468 158  145
259  2589  6   | 28     4    1    | 7   589  3
4    89    1   | 367    578  367  | 689 2    59
---------------+------------------+---------------
1259 2459  7   | 249    3    8    | 49  19   6
1269 24689 289 | 2479   2579 2457 | 489 3    12479
3    2489  289 | 1      6    247  | 5   789  2479
---------------+------------------+---------------
259  1     259 | 246789 2789 2467 | 3   5679 579
8    5679  4   | 367    1    367  | 2   5679 579
269  2679  3   | 5      279  267  | 1   4    8


[tarek]

Hi throbdude,

You've missed a Hidden Single in Column6

But the next step you're after is a HIDDEN Triple in Column 9

Tarek

[throbdude]

Hey ... good call on the hidden single!!!!

But, I don't know what a hidden Triple looks like or what you do with it?

Is it the 579? Doesn't there have to be 3 of them? I only see 2.

Code: Select all

7    3     258 | 268    258  9    | 468 158  145
259  2589  6   | 28     4    1    | 7   589  3
4    89    1   | 367    578  367  | 689 2    59
---------------+------------------+---------------
1259 2459  7   | 249    3    8    | 49  19   6
1269 24689 289 | 2479   279  5    | 489 3    12479
3    2489  289 | 1      6    247  | 5   789  2479
---------------+------------------+---------------
259  1     259 | 246789 2789 2467 | 3   5679 579
8    5679  4   | 367    1    367  | 2   5679 579
269  2679  3   | 5      279  267  | 1   4    8


[vidarino]

The 579 is actually a Naked Triple (one 59 + two 579s), which means that you can eliminate 5, 7 and 9 from the rest of the cells in the column.

The hidden one, which IMHO is less obvious to find, is 124. Combined, these three candidates only occupy three different cells, which means that you can eliminate the other candidates in those three cells.

The net result of applying either of these two techniques is identical, though.

[throbdude]

Yes yes ...I see that now ... and the 259 in column 1 too. Mmmmm.

Column 2 looks confusing for a 289 triple ...I'm guessing that I can't apply anything to that one.

In any case, I now have a new tool in my belt now. Thanks!

[Cec]

"Yes yes ...I see that now ... and the 259 in column 1 too. Mmmmm.
Column 2 looks confusing for a 289 triple ...I'm guessing that I can't apply anything to that one..."

Hi throbdude,
If you are wondering whether the 259 in column 1 is a triple the answer is NO. A triple, whether "naked" or "hidden", requires three candidates or a combination of these same candidates, to appear only in three cells of a unit (row, column or box). In column 1 these three candidates appear in five cells. For similar reasons the 289 in column 2 isn't a triple either. The angusj link suggested above by Crazy Girl provides good examples to help identify triples.

Cec

[throbdude]

While I admit I don't have enough solving tools in my pocket yet, this one seems very difficult.
Am I missing something basic or do I need a new tool to figure this one out?

Code: Select all

 *-----------*   *--------------------------------------------------*
 |541|326|987|   | 5    4    1    | 3    2    6    | 9    8    7    |
 |769|851|243|   | 7    6    9    | 8    5    1    | 2    4    3    |
 |328|974|651|   | 3    2    8    | 9    7    4    | 6    5    1    |
 |---+---+---|   |----------------+----------------+----------------|
 |9.4|..7|528|   | 9    13   4    | 16   136  7    | 5    2    8    |
 |857|4.2|.96|   | 8    5    7    | 4    13   2    | 13   9    6    |
 |6.2|598|7.4|   | 6    13   2    | 5    9    8    | 7    13   4    |
 |---+---+---|   |----------------+----------------+----------------|
 |49.|7.5|8.2|   | 4    9    36   | 7    16   5    | 8    13   2    |
 |28.|.49|.75|   | 2    8    36   | 16   4    9    | 13   7    5    |
 |175|283|469|   | 1    7    5    | 2    8    3    | 4    6    9    |
 *-----------*   *--------------------------------------------------*

[Kent]

I think u can solve using remote pair.

[TKiel]

throbdude,

This is a BUG+1 grid which is explained in this link www.sudoku.com/boards/viewtopic.php?t=2352. Basically if r4c5 were also a bivalue cell, like the rest of the unsolved cells, then the puzzle would not have a unique solution. Any candidate in r4c5 that appears only twice in a group which includes that cell can be excluded, which will leave only a single possible candidate in that cell. Another way to look at it is the value in r4c5 that appears three times in a group must be assigned to that cell. r4c5 must be 1 in either case.

Tracy