The New Sudoku Players' Forum

[markf]

Hi Cec:
Can I impose on your solving largesse one more time? This was the original,


*-----------*
|...|3..|..6|
|...|.8.|1..|
|...|.65|.72|
|---+---+---|
|.4.|.2.|.61|
|..5|...|7..|
|23.|.1.|.8.|
|---+---+---|
|12.|47.|...|
|..6|.9.|...|
|8..|..6|...|
*-----------*
and I have it to here:



*-----------------------------------------------------------*
| 57 5789 12 | 3 4 12 | 589 59 6 |
| 45 6 29 | 7 8 29 | 1 345 35 |
| 3 89 149 | 19 6 5 | 489 7 2 |
|-------------------+-------------------+-------------------|
| 9 4 8 | 5 2 7 | 3 6 1 |
| 6 1 5 | 89 3 89 | 7 2 4 |
| 2 3 7 | 6 1 4 | 59 8 59 |
|-------------------+-------------------+-------------------|
| 1 2 39 | 4 7 38 | 6 359 3589 |
| 457 57 6 | 18 9 138 | 2 34 378 |
| 8 79 349 | 2 5 6 | 49 1 379 |
*-----------------------------------------------------------*

I don't think I have made any mistakes. Do you see a way to solve this one without brute force?

Last time I ask, promise. Well not the last. There I said it.

Stuck in Halifax,
Mark

[Cec]

Hi Cec:
Can I impose on your solving largesse one more time? ...
..Last time I ask, promise. Well not the last. There I said it.

Mark, again no offence, but there are reasons why I can't take up your offer.

I'm happy to help when I can with puzzles that are within my capabilities to solve. The Simple Suduko Solver program shows this puzzle ultimately requires "multiple colours" knowledge which is one of a number of advanced techniques that are beyond me. I hope to eventually learn these.

Whilst I'm flattered with your offer - I haven't stopped telling my wife about it all day - it is the 'norm' to post any query to the open forum - and as a new subject rather than a continuation of this different subject thread - I'm sure somebody having more advanced knowledge would offer to help you. For sending a new post you click on the "new topic" window in the top left hand corner.

To make you feel better - I now know what the word "largesse" means (I hope I've spelt it right) and you progressed further on this puzzle than I did!

Cheers, Cec

[rubylips]

Mark,

Unless I've overlooked a clever trick, this is a very tough puzzle. I assume you found it on the internet rather than in the daily press. Here's the solver log for the next four moves:

Code: Select all

17. Consider the chain r7c9~3~r7c3~9~r9c2-7-r9c9-7-r8c9-8-r7c9.
When the cell r7c9 contains the value 3, it likewise contains the value 8 - a contradiction.
Therefore, the cell r7c9 cannot contain the value 3.
- The move r7c9:=3 has been eliminated.
Consider the chain r8c6-3-r7c6~3~r7c3~9~r9c2-7-r9c9-7-r8c9.
When the cell r8c9 contains the value 3, some other value must occupy the cell r8c6, which means that the value 7 must occupy the cell r8c9 - a contradiction.
Therefore, the cell r8c9 cannot contain the value 3.
- The move r8c9:=3 has been eliminated.
Consider the chain r9c3-4-r3c3-1-r3c4-9-r5c4~9~r5c9~4~r9c9.
When the cell r9c9 contains the value 4, so does the cell r9c3 - a contradiction.
Therefore, the cell r9c9 cannot contain the value 4.
- The move r9c9:=4 has been eliminated.
Consider the chain r3c3~9~r7c3~3~r7c6~8~r5c6-8-r5c4-9-r3c4.
When the cell r3c3 contains the value 9, so does the cell r3c4 - a contradiction.
Therefore, the cell r3c3 cannot contain the value 9.
- The move r3c3:=9 has been eliminated.
Consider the chain r8c6-1-r1c6-1-r1c3-2-r2c3~9~r7c3~3~r7c6-3-r8c6.
The cell r8c6 must contain the value 3 if it doesn't contain the value 1.
Therefore, these two values are the only candidates for the cell r8c6.
- The move r8c6:=8 has been eliminated.
Consider the chain r5c9-4-r5c6-8-r5c4-8-r8c4-8-r8c9.
When the cell r8c9 contains the value 4, some other value must occupy the cell r5c9, which means that the value 8 must occupy the cell r8c9 - a contradiction.
Therefore, the cell r8c9 cannot contain the value 4.
- The move r8c9:=4 has been eliminated.
Consider the chain r9c8-1-r9c4-2-r8c4-8-r8c9-7-r9c9-7-r9c2~9~r9c8.
When the cell r9c8 contains the value 9, it likewise contains the value 1 - a contradiction.
Therefore, the cell r9c8 cannot contain the value 9.
- The move r9c8:=9 has been eliminated.
Consider the chain r7c6-3-r8c6-1-r1c6-1-r1c3-2-r2c3~9~r7c3~3~r7c8.
When the cell r7c8 contains the value 3, so does the cell r7c6 - a contradiction.
Therefore, the cell r7c8 cannot contain the value 3.
- The move r7c8:=3 has been eliminated.
The values 1, 3 and 4 occupy the cells r2c8, r8c8 and r9c8 in some order.
- The move r2c8:=5 has been eliminated.
Consider the chain r1c3-1-r1c6-1-r8c6-3-r7c6-3-r7c3.
The cells r1c3 and r7c3 contain one value from the set {1,3} and another from {2,9}.
The values 2 and 9 occupy 2 of the cells r1c3, r7c3 and r2c3 in some order.
- The move r9c3:=9 has been eliminated.
Consider the chain r1c2~9~r1c8-9-r7c8~9~r7c3-9-r2c3.
When the cell r1c2 contains the value 9, so does the cell r2c3 - a contradiction.
Therefore, the cell r1c2 cannot contain the value 9.
- The move r1c2:=9 has been eliminated.
The value 9 in Box 3 must lie in Row 1.
- The move r3c7:=9 has been eliminated.
Consider the chain r7c9-5-r7c8-5-r1c8-9-r1c7-8-r1c2-8-r3c2-9-r9c2-9-r7c3-3-r7c6-8-r7c9.
When the cell r7c9 contains the value 5, it likewise contains the value 8 - a contradiction.
Therefore, the cell r7c9 cannot contain the value 5.
- The move r7c9:=5 has been eliminated.
The cell r7c8 is the only candidate for the value 5 in Row 7.
18. The value 9 is the only candidate for the cell r1c8.
19. Consider the chain r2c6-9-r2c3-9-r7c3-9-r7c9~9~r9c7-9-r6c7~9~r6c6.
When the cell r6c6 contains the value 9, so does the cell r2c6 - a contradiction.
Therefore, the cell r6c6 cannot contain the value 9.
- The move r6c6:=9 has been eliminated.
The value 4 is the only candidate for the cell r6c6.
20. The cell r5c9 is the only candidate for the value 4 in Row 5.
21. Consider the chain r2c9-3-r2c8-4-r3c7-8-r3c2-9-r9c2-7-r9c9.
When the cell r9c9 contains the value 3, some other value must occupy the cell r2c9, which means that the value 7 must occupy the cell r9c9 - a contradiction.
Therefore, the cell r9c9 cannot contain the value 3.
- The move r9c9:=3 has been eliminated.
The cell r2c9 is the only candidate for the value 3 in Column 9.


[bennys]

Code: Select all

+----------------+----------------+----------------+
| 57   5789 12   | 3    4    12   | 589  59   6    |
| 45   6    29   | 7    8    29   | 1    345  35   |
| 3    89   149  | 19   6    5    | 489  7    2    |
+----------------+----------------+----------------+
| 9    4    8    | 5    2    7    | 3    6    1    |
| 6    1    5    | 89   3    89   | 7    2    4    |
| 2    3    7    | 6    1    4    | 59   8    59   |
+----------------+----------------+----------------+
| 1    2   *39   | 4    7    38   | 6    359  3589 |
| 457  57   6    | 18   9    138  | 2    34   378  |
| 8   *79  *349  | 2    5    6    |*49   1    379  |
+----------------+----------------+----------------+

 If R9C7 = 9 then R9C2 =7
 If R9C7 = 4 then again R9C2 =7 because of R9C3 and R7C3


[rubylips]

Spotter's Badge, bennys! I'll be able to recognize such situations once I've generalized the Conditional Disjoint Subsets technique to consider link cells with more than two candidates. In the given position, when r9c3 (the link cell) contains 3 or 9, the values 3 and 9 in Box 7 must occupy the cells r7c3 and r9c3. When it contains 4 or 9, the values 4 and 9 in Row 9 must occupy the cells r9c3 and r9c7. Whichever value it takes, the value 9 can't exist as a candidate in the Row 9/Box 7 intersection, which includes r9c2.

[markf]

Thanks everyone for the solving and posting tips. I think I may have waded in slightly over my head...

Mark

[ronk]

and I have it to here:

Code: Select all

 *-----------------------------------------------------------*
 | 57    5789  12    | 3     4     12    | 589   59    6     |
 | 45    6     29    | 7     8     29    | 1     345   35    |
 | 3     89    149   | 19    6     5     | 489   7     2     |
 |-------------------+-------------------+-------------------|
 | 9     4     8     | 5     2     7     | 3     6     1     |
 | 6     1     5     | 89    3     89    | 7     2     4     |
 | 2     3     7     | 6     1     4     | 59    8     59    |
 |-------------------+-------------------+-------------------|
 | 1     2     39    | 4     7     38    | 6     359   3589  |
 | 457   57    6     | 18    9     138   | 2     34    378   |
 | 8     79    349   | 2     5     6     | 49    1     379   |
 *-----------------------------------------------------------*

If you please, I would like to know how you pinned r3c1=3 and r6c6=4.

TIA, Ron

[markf]

Hi Ron:
I started the puzzle last weekend and worked on it scrap paper and computer (just to mark-up) and then posted on tuesday, and can't find the work ( i feel like i'm in school) so I don't know how to get r6c6 or r3c1. As I've looked at it though, and given my evaluation of my skill level I think that I must have made a mistake that just worked out. In other words, can you tell me how I pinned r6c6? The sad thing is that even if I plug 4 into that cell I can't even figure out how I got the 3 in r3c1. So to quote myself from earlier in this post, or another was it another post, basically I'm an idiot.

I'm going to keep plugging away, but confidence is not high.

Mark

[emm]

markf, those errors are called happy accidents. Almost absolutely everybody here has made at least one of them, I personally have made at least two. I think of those first published mistakes as a kind of initiation into the forum, a rite of passage. Idiocy doesn’t come into it - they are just little speed bumps on the road to mastery!

[Cec]

markf, those errors are called happy accidents.... Idiocy doesn’t come into it - they are just little speed bumps on the road to mastery!

I was wondering what else to say to Mark and I couldn't put it any better. Ah! a woman's touch again - stay with us Mark, it will get better!

Cec

[ronk]

In other words, can you tell me how I pinned r6c6

That's where I was stumped, so was just hoping to learn (or relearn) a technique. But don't feel bad, I just published a happy accident a couple days ago myself.

[Guest]

I found two solutions for this one!

Code: Select all

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

and

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



[ronk]

I found two solutions for this one!

The puzzle originally posted was missing a couple of clues. The 3rd message on this topic has the corrected puzzle.

[markf]

Hi Ron,(and all the others who looked at this)

After a break and some practice
I went back and looked at the puzzle in this thread, to refresh everyone's memory:


*-----------*
|...|3..|..6|
|...|.8.|1..|
|...|.65|.72|
|---+---+---|
|.4.|.2.|.61|
|..5|...|7..|
|23.|.1.|.8.|
|---+---+---|
|12.|47.|...|
|..6|.9.|...|
|8..|..6|...|
*-----------*




that I had gotten to this far before I had a happy accident. (which is an earlier post) Up to this point there hasn't been anything too tricky to my newbie mind. Anyway, I think I found a way to solve it from this point:


*-----------------------------------------------------------*
| 579 5789 12 | 3 4 12 | 589 59 6 |
| 459 6 249 | 7 8 29 | 1 3459 3459 |
| 34 89 1349 | 19 6 5 | 489 7 2 |
|-------------------+-------------------+-------------------|
| 79 4 8 | 5 2 79 | 3 6 1 |
| 6 1 5 | 89 3 489 | 7 2 49 |
| 2 3 79 | 6 1 479 | 459 8 459 |
|-------------------+-------------------+-------------------|
| 1 2 39 | 4 7 38 | 6 359 3589 |
| 3457 57 6 | 128 9 138 | 24 134 3478 |
| 8 79 3479 | 12 5 6 | 249 1349 3479 |
*-----------------------------------------------------------

I was able to eliminate 7 from r6c6, (if r5c4 = 8, then r3c4 = 9, r3c2=8,r3c7=4, r8c7=2, r9c7=9, r2c2=7, so r1c1=7, r4c1=9, r6c3=7 so r6c6 doesn't equal 7.
if r5c4=9, then r6c6=4 and not 7; pardon my notation)


which made r6c3= 7, which leads to this:




*-----------------------------------------------------------*
| 57 5789 12 | 3 4 12 | 589 59 6 |
| 45 6 249 | 7 8 29 | 1 3459 3459 |
| 34 89 1349 | 19 6 5 | 489 7 2 |
|-------------------+-------------------+-------------------|
| 9 4 8 | 5 2 7 | 3 6 1 |
| 6 1 5 | 89 3 489 | 7 2 49 |
| 2 3 7 | 6 1 49 | 459 8 459 |
|-------------------+-------------------+-------------------|
| 1 2 39 | 4 7 38 | 6 359 3589 |
| 3457 57 6 | 128 9 138 | 24 134 3478 |
| 8 79 349 | 12 5 6 | 249 1349 3479 |
*-----------------------------------------------------------*

and then bennys' trick still works, whatever the value of r9c3 is, the r9c2 is 7. (I never would have spotted this myself), then the puzzle can be worked out.

Thanks,
mark

[rubylips]

markf,

You're not the only one to have improved over the past couple of weeks. My solver now finds the following chain:

Code: Select all

Consider the chain r3c7+<4|1>+r3c4~1~r9c4-2-r8c4-2-r8c7.
When the cell r8c7 contains the value 4, some other value must occupy the cell r3c7, which means that the value 2 must occupy the cell r8c7 - a contradiction.
Therefore, the cell r8c7 cannot contain the value 4.
- The move r8c7:=4 has been eliminated.
The value 2 is the only candidate for the cell r8c7.


The idea behind the link r3c7+<4|1>+r3c4 is that when r3c7 doesn't contain 4, the values 8 and 9 occupy r3c2 and r3c7 so r3c4 has to contain 1.