The New Sudoku Players' Forum

[yorm]

I'm sort of new to this, so I apologize if this puzzle is too easy.

Here's the start:
7-3 8-- --4
--- -57 ---
--- --- 2-8

-4- 2-8 3--
8-- 7-5 --2
--2 9-4 -1-

2-9 --- ---
--- 47- ---
6-- --9 1-3

I've gotten this far:

713 892 --4
428 657 931
--- -4- 278

-47 2-8 3--
8-- 7-5 4-2
--2 9-4 817

2-9 --- 74-
-8- 47- -29
674 529 183

Please explain how I can solve any other cells at this point.

Thanks!

[yorm]

Sorry for the formatting. I didn't see the instructions until after I posted this.

[tarek]

Hi there,

Is it possible to post the candidate list.

Try checking the sticky post Explaining how to post a puzzle.

The reason is with a candidate list, we can trace your solving methods & see if a correct one was made &or if there was a mistake....

if you do not deal with candidates then.......


Where would you place an 8 in column 5???

Tarek

[yorm]

Thanks for the reply. Yes - I missed the 8 in column 5 when I posted the original message.

Here are the candidates I have:

Code: Select all

*---------------+---------------+---------------*
|   7   1   3   |   8   9   2   |   56  56  4   |
|   4   2   8   |   6   5   7   |   9   3   1   |
|   59  569 56  |   13  4   13  |   2   7   8   |   
|---------------+---------------+---------------|
|   19  4   7   |   2   16  8   |   3   569 56  |
|   8   369 16  |   7   136 5   |   4   69  2   |
|   35  356 2   |   9   36  4   |   8   1   7   |
|---------------+---------------+---------------|
|   2   35  9   |   13  8   136 |   7   4   56  |
|   135 8   15  |   4   7   36  |   56  2   9   |
|   6   7   4   |   5   2   9   |   1   8   3   |
*-----------------------------------------------*


Thanks again!

[tarek]

Much clearer now, what you need now is an xy wing, look at BIVALUED cells, with any combination from the following digits 1,6,9

Don't read further.... if you want to try that first......



Now look at cell r5c3....& look at the 2 cells r5c8 & r4c1.....


Don't read further....if you want to try that first.....



Here is the actual step & eliminations...

Code: Select all

*-----------------------------------------------*
| 7    1    3   | 8    9    2   | 56   56   4   |
| 4    2    8   | 6    5    7   | 9    3    1   |
| 59   569  56  | 13   4    13  | 2    7    8   |
|---------------+---------------+---------------|
|*19   4    7   | 2    16   8   | 3   -569  56  |
| 8   -369 *16  | 7    136  5   | 4   *69   2   |
| 35   356  2   | 9    36   4   | 8    1    7   |
|---------------+---------------+---------------|
| 2    35   9   | 13   8    136 | 7    4    56  |
| 135  8    15  | 4    7    36  | 56   2    9   |
| 6    7    4   | 5    2    9   | 1    8    3   |
*-----------------------------------------------*
Eliminating 9 From r5c2 (6 & 1 in r5c3 form an XY wing with 9 in r5c8 & r4c1)
Eliminating 9 From r4c8 (6 & 1 in r5c3 form an XY wing with 9 in r5c8 & r4c1)

tarek

[yorm]

I see that now. Thank you!

I've been doing these puzzles for a couple months now (mostly the easier ones obviously) and it's great to learn something new!

[QBasicMac]

Nice answer, Tarek.

I have nothing to add, but noticed that I have responded to many puzzles and just wanted one more (for fun)



Mac

[Neunmalneun]

There is also a Uniqueness Rectangle ("13" in R3C46/R7C46) allowing the elimination of "1" and "3" in R7C6. This leaves a "6"in this cell and the rest is singles.

[Cec]

My apologies if this description is not clear but I can vaguely recall an interesting thread - I think from tso - relating to a "naked pair" and another candidate occupying a third cell which includes the same candidates making up the naked pair - in this case the [56] in column9 and [569] in r4c8 of Tarek's above grid - whereby if the same numbers for that naked pair occur in the same row, column and box, then (and this is where I'm more confused) this would lead to either a placement or exclusion of the candidate9 in/from cell r4c8. Confirmation of my "thoughts" - within reason - would be appreciated. BTW I endorse Mac's acknowledgement of Tarek's above answer and its presentation.
Cec

[ravel]

Hi cecbevwr, i think you are referring to MrHamiltons assumption here, which proved to be wrong. Also note that the three 56-pairs in boxes 3,6 and 9 (without the 9 in r4c8) do not form a deadly uniqueness pattern (as i thought at the first glance), because the pair in box 9 does not lie in the same row.

[Cec]

Hi cecbevwr, i think you are referring to MrHamiltons assumption here, which proved to be wrong..."

Thanks ravel and "Cec" would do fine - It's probably time I looked into changing the "cecbevwr" - it's too hard to type!

No, I'm fairly sure the "pattern" I recalled couldn't have been Mr Hamilton's assumption which, as you say, proved to be wrong. I'm still fairly sure the "pattern" I'm thinking of was described by tso a month or so back and was a valid solving aid and had some similarity to Mr Hamilton's assumption. Thinking about this again, if the particular solving "pattern" I'm trying to recall did exist in tarek's above grid then I'm fairly sure "it" would have been previously spotted and acted upon by one of the forum's more experienced solvers.
Cec

[tso]

Could you be thinking of"remote pairs" aka "remote naked pairs"? (This cannot be applied to this puzzle -- almost, but not quite.)

[Cec]

"Could you be thinking of"remote pairs" aka "remote naked pairs"?..."

Thanks tso and yes, I'm pretty sure this is the pattern I had in mind.
Cec