Need help to advance...

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Need help to advance...

Postby Sudtyro » Sat Jan 20, 2007 11:35 pm

Need hint to advance beyond the following:

Code: Select all
569  156   2    | 156  569  8    | 3   7   4
3589 1358  589  | 4    7    1359 | 58  2   6 
4    35678 578  | 2    356  356  | 58  1   9 
----------------+----------------+-----------
2    3578  4    | 5678 3568 356  | 1   9   58
1    58    6    | 58   29   29   | 4   3   7 
358  9     578  | 1578 4    135  | 2   6   58
----------------+----------------+-----------
5689 2     1    | 568  568  7    | 69  4   3
7    568   589  | 3    1    4    | 69  58  2
568  4     3    | 9    2568 256  | 7   58  1


All suggestions welcome!
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Postby tarek » Sun Jan 21, 2007 3:20 pm

Looking at the PMs, I couldn't see anything obvious........

could u supply the original puzzle?

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Postby Sudtyro » Sun Jan 21, 2007 6:22 pm

Sure...here's the original:

Code: Select all
.  .  2  | .  .  8  | 3  .  .
.  .  .  | 4  7  .  | .  .  6 
4  .  .  | 2  .  .  | .  1  . 
---------+----------+--------
.  .  4  | .  .  .  | .  9  .
1  .  6  | .  .  .  | 4  .  7
.  9  .  | .  .  .  | 2  .  .
---------+----------+--------
.  2  .  | .  .  7  | .  .  3
7  .  .  | .  1  4  | .  .  .
.  .  3  | 9  .  .  | 7  .  .
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Postby tarek » Sun Jan 21, 2007 6:55 pm

No....

I couldn't spot anything easy......no even an almost locked sets rules...

It looks like some complex chains are needed.........

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Re: Need help to advance...

Postby Sudtyro » Sun Jan 21, 2007 9:51 pm

Right, I saw that "almost" UR, too, and used the link between (9)r2c3 and (7)r3c3 as a bridge in some 3D coloring, but couldn't make any headway there either.

Is there a non-T&E method that will also advance this puzzle?
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Postby Sudtyro » Sun Jan 21, 2007 9:57 pm

Sorry...I somehow killed the post that preceded mine. It referred to the 58 "almost" UR.:(
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Postby daj95376 » Sun Jan 21, 2007 10:06 pm

Sudtyro wrote:Sorry...I somehow killed the post that preceded mine. It referred to the 58 "almost" UR.:(

You didn't kill my post. I withdrew it while you were (apparently) preparing a reply. I checked the contradiction chain for [r2c3]=9 and it was a nightmare. So, it didn't make my suggestion/post feasible. I'm sorry!
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Postby Sudtyro » Tue Jan 23, 2007 8:25 pm

So, does this mean that only T&E will advance this puzzle?
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Too Tough

Postby Pat » Thu Feb 01, 2007 10:44 am

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




Need hint to advance beyond the following:

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


Code: Select all
569  156   2    | 156  569  8    | 3   7   4
3589 1358  589  | 4    7    1359 | 58  2   6 
4    35678 578  | 2    356  356  | 58  1   9 
----------------+----------------+-----------
2    3578  4    | 5678 3568 356  | 1   9   58
1    58    6    | 58   29   29   | 4   3   7 
358  9     578  | 1578 4    135  | 2   6   58
----------------+----------------+-----------
5689 2     1    | 568  568  7    | 69  4   3
7    568   589  | 3    1    4    | 69  58  2
568  4     3    | 9    2568 256  | 7   58  1 




      hey Sudtyro, looks like you found a real tough one

      so i thought i'd check out Sudoku Explainer
      -- this is what i got:
        Multiple Forcing Chains to exclude the 6 at r1c4:
        • b1 6 in r1 immediately excludes the 6 at r1c4
        • b1 6 in r3c2 puts the r3 7 in c3, the r6 7 in c4, the c4 1 in r1
        Forcing Chain to exclude the 5 at r2c2

        etc etc
      too tough for me
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Re: Too Tough

Postby Sudtyro » Wed Feb 07, 2007 6:30 pm

Pat wrote:too tough for me



I'm shocked! And coming from someone who can spot a "finned mutant swordfish" to boot!:)
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Postby Pat » Mon Feb 12, 2007 11:17 am

    but now Carcul is back

    perhaps we'll see some action here --
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Postby udosuk » Wed Feb 14, 2007 4:25 pm

Before Carcul terrifies us with his amazing chains, here is my effort to solve this one...:)
(I'm no chain notation expert though, so the notation police please feel free to correct me...)

After basic techniques (SSTS):
Code: Select all
 *--------------------------------------------------------------------*
 |*569   *156    2      |*156    569    8      | 3      7      4      |
 |*3589   1358  *589    | 4      7      1359   |#58     2      6      |
 | 4     -73568 *578    | 2      356    356    |#58     1      9      |
 |----------------------+----------------------+----------------------|
 | 2     @3578   4      |@5678   3568   356    | 1      9      58     |
 | 1      58     6      | 58     29     29     | 4      3      7      |
 | 358    9      578    | 1578   4      135    | 2      6      58     |
 |----------------------+----------------------+----------------------|
 |*5689   2      1      |*568    568    7      |*69     4      3      |
 | 7      568    589    | 3      1      4      | 69     58     2      |
 | 568    4      3      | 9      2568   256    | 7      58     1      |
 *--------------------------------------------------------------------*

There is a potential UR {58} in r23c37 => r23c3 must have 7|9
[r3c2](-7-[r4c2]=7=[r4c4])-7|9=[r23c3]-9-[r12c1]=9=[r7c1]-9-[r7c7]-6-[r7c4]=6=[r1c4]-6-[r1c12]=6=[r3c2]
Therefore r3c2<>7

After a few more singles/locked candidates:
Code: Select all
 *-----------------------------------------------------------*
 | 56   *56    2     | 1     9     8     | 3     7     4     |
 | 89    1     89    | 4     7     3     | 5     2     6     |
 | 4     3     7     | 2     56    56    | 8     1     9     |
 |-------------------+-------------------+-------------------|
 | 2     7     4     | 568   3     56    | 1     9     58    |
 | 1    *58    6     |*58    2     9     | 4     3     7     |
 | 3     9     58    | 7     4     1     | 2     6     58    |
 |-------------------+-------------------+-------------------|
 | 5689  2     1     |*56    568   7     |*69    4     3     |
 | 7    -658   589   | 3     1     4     |*69    58    2     |
 | 568   4     3     | 9     568   2     | 7     58    1     |
 *-----------------------------------------------------------*

There is a relatively short xy-chain:

[r8c2]-6-[r8c7]=6=[r7c7]-6-[r7c4]-5-[r5c4]=5=[r5c2]-5-[r1c2]-6-[r8c2]
Therefore r8c2<>6, and the puzzle is solved.

Or alternatively, we can do an ALS-xyz:
Code: Select all
 *-----------------------------------------------------------*
 | 56   *56    2     | 1     9     8     | 3     7     4     |
 | 89    1    @89    | 4     7     3     | 5     2     6     |
 | 4     3     7     | 2     56    56    | 8     1     9     |
 |-------------------+-------------------+-------------------|
 | 2     7     4     | 568   3     56    | 1     9     58    |
 | 1    -58    6     |*58    2     9     | 4     3     7     |
 | 3     9    @58    | 7     4     1     | 2     6     58    |
 |-------------------+-------------------+-------------------|
 | 5689  2     1     |*56    568   7     | 69    4     3     |
 | 7    #568  #589   | 3     1     4     | 69   #58    2     |
 | 568   4     3     | 9     568   2     | 7     58    1     |
 *-----------------------------------------------------------*

A=r1c2={56}
B=r26c3={589}
C=r8c238={5689}
x (common to A,B)=5
y (restricted common to A,C)=6
z (restricted common to B,C)=9

Therefore r5c2<>5, and the puzzle is solved.

Solution:

562198374
918473526
437265819
274836195
186529437
395741268
821657943
759314682
643982751

:idea:
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Another Solution

Postby Carcul » Thu Feb 15, 2007 11:13 am

Sudtyro wrote:Need hint to advance beyond the following:


Code: Select all
 *-----------------------------------------------------------*
 | 569    156    2   | 156    569    8    | 3      7      4  |
 | 3589   1358   589 | 4      7      1359 | 58     2      6  |
 | 4      35678  578 | 2      356    356  | 58     1      9  |
 |-------------------+--------------------+------------------|
 | 2      3578   4   | 5678   3568   356  | 1      9      58 |
 | 1      58     6   | 58     29     29   | 4      3      7  |
 | 358    9      578 | 1578   4      135  | 2      6      58 |
 |-------------------+--------------------+------------------|
 | 5689   2      1   | 568    568    7    | 69     4      3  |
 | 7      568    589 | 3      1      4    | 69     58     2  |
 | 568    4      3   | 9      2568   256  | 7      58     1  |
 *-----------------------------------------------------------*

[r8c3]=9=[r7c1](-9-[r7c7]-6-[r7c45])-9-[r1c1]=9=[r1c5]-9-[r2c6]=9=
=[r5c6]=2=[r9c6]=6=[r9c5]-6-[r9c1]=6=[r8c2](-6-[r1c2])-6-[r3c2]=6=
=[r3c56]-6-[r1c4]=6=[r4c4]=7=[r4c2]-7-[r3c2]=7=[r3c3],

but this cannot be, because now we have an incompatible pattern of “5s” in cells {r1c24|r3c25|r5c24|r7c45}.

So, r8c3 must be “9” and the puzzle is solved.

Udosuk wrote:here is my effort to solve this one...


Nice solution. Here is still another alternative for your last step:

[r8c3]=9=[r2c3]=8=[r2c1]-8-[r79c1]=8=[r8c23]-8-[r8c8]-5-[r8c3], => r8c3<>5.

Carcul
Last edited by Carcul on Thu Feb 15, 2007 10:33 am, edited 1 time in total.
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Re: Another Solution

Postby udosuk » Thu Feb 15, 2007 1:58 pm

Carcul wrote:...but this cannot be, because now we have an incompatible pattern of “5s” in cells {r1c24|r3c256|r4c56|r5c24|r7c45}.

Thanks for the compliments on my solutions, but as always I'm puzzled by yours...:!: I simply cannot see the incompatible pattern of 5s...:(

After I run through your steps, I get the 5s in r1c24|r5c24|r7c45 but the 5 on r3 can be in r3c2567 and on r4 it can be in r4c569... So I'm not sure where you eliminated the 5s from r3c7 and r4c9...:?:
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Postby Carcul » Thu Feb 15, 2007 2:32 pm

Udosuk wrote:I simply cannot see the incompatible pattern of 5s...


That's because I have written too many cells. Thanks, I have edited the post.

Carcul
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