The New Sudoku Players' Forum

[urhegyi]

01-09-create.png (15.9 KiB) Viewed 648 times

I took a grid from the pattern games with 4 open boxes, added a few more clues in these boxes and so a had my first sudoku ever that I created myself. It has a unique solution(is valid) and apart from the basics it's a one trick pony. (just one advanced step needed, stte). If you like have a look at this and I appreciate feedback on the difficulty of it.

[Pupp]

Nice puzzle.

Sudoku Explainer gave it a 5.5 rating, but I blitz through the puzzle with easier techniques than what SE suggested. Still, it had a nice balance of different techniques.

[Leren]

Code: Select all

*------------------------------------*
| 1 9 6  | 2     4  7   | 3    5   8 |
| 8 2 7  | 3     5  1   | 4    6   9 |
| 3 4 5  | 68    9  68  | 27   27  1 |
|--------+--------------+------------|
| 7 8 24 | 1     6  49  | 29   3   5 |
| 5 6 1  | 89    2  3   | 89   4   7 |
| 9 3 24 | 578   78 458 | 1    28  6 |
|--------+--------------+------------|
| 6 7 89 |d589   3  2   |c58   1   4 |
| 4 5 3  |e789-6 1  689 |a68-7 789 2 |
| 2 1 89 | 4     78 56  |b56   789 3 |
*------------------------------------*

(6) r8c7 = (6-5) r9c7 = r7c7 - r7c4 = (5-7) r6c4 = (7) r8c4 => - 6 r8c4, - 7 r8c7; stte, or

Code: Select all

*------------------------------------*
| 1 9 6  | 2    4   7   | 3    5   8 |
| 8 2 7  | 3    5   1   | 4    6   9 |
| 3 4 5  |*68   9  *68  | 27   27  1 |
|--------+--------------+------------|
| 7 8 24 | 1    6   49  | 29   3   5 |
| 5 6 1  |*89   2   3   |*89   4   7 |
| 9 3 24 | 578  78  458 | 1    28  6 |
|--------+--------------+------------|
| 6 7 89 | 589  3   2   | 5-8  1   4 |
| 4 5 3  |*6789 1  *689 |*678 f789 2 |
| 2 1 89 | 4    78  56  | 56   789 3 |
*------------------------------------*

Finned Swordfish in 8's r358 c467 fin Cell r8c8 => - 8 r7c7; stte

Leren

[Pupp]

Original Puzzle

Code: Select all

 *-----------*
 *--------------------------------------------------------------------*
 | 1      9      6      | 2      4      7      | 3      5      8      |
 | 8      2      7      | 3      5      1      | 4      6      9      |
 | 3      4      5      | 68     9      68     | 27     27     1      |
 *----------------------+----------------------+----------------------|
 | 7      8      24     | 1      6      4569   | 2569   3      256    |
 | 5      6      1      | 89     2      3      | 89     4      7      |
 | 9      3      24     | 5678   678    4568   | 1      28     256    |
 *----------------------+----------------------+----------------------|
 | 6      7      89     | 589    3      2589   | 2589   1      4      |
 | 4      5      3      | 6789   1      2689   | 26789  2789   26     |
 | 2      1      89     | 4      678    5689   | 56789  789    3      |
 *--------------------------------------------------------------------*


FYI I didn't use the steps that Sudoku Explainer uses
_____________________________________________________________
Sudoku Explainer
Analysis results
Difficulty rating: 5.5 (3 Strong links (including blocks) 0011)
This Sudoku can be solved using the following logical methods:
29 x Hidden Single
2 x Direct Hidden Pair
1 x Pointing 1 x Hidden Pair
1 x 3 Strong links (including blocks) 0011
The most difficult technique (ER): 3 Strong links (including blocks) 0011
______________________________________________________________

Puzzle at the critical point:
*--------------------------------------------------------------------*
| 1 9 6 | 2 4 7 | 3 5 8 |
| 8 2 7 | 3 5 1 | 4 6 9 |
| 3 4 5 | 68 9 68 | 27 c27 1 |
*----------------------+----------------------+----------------------|
| 7 8 24 | 1 6 459 | 29 3 25 |
| 5 6 1 | 89 2 3 | 89 4 7 |
| 9 3 a24 | 578 78 458 | 1 b28 256 |
*----------------------+----------------------+----------------------|
| 6 7 89 | 589 3 2589 | 2589 1 4 |
| 4 5 3 | 6789 1 2689 | 26789 2789 26 |
| 2 1 89 | 4 78 56 | 56 789 3 |
*--------------------------------------------------------------------*

look at r6c3(2,4) as "a", then r6c8(2,8) as "b", then r3c8(2,7) as "c": that means "b"r6c8=8 which is the number that is NOT the common denominator. Also note that the NOT common denominator numbers are all different. So it's 3 different pairs of numbers with a single common denominator number.

After that, the puzzle pretty much just falls apart.

[Here's the puzzle as code, sans colored numbers and letters]:

Code: Select all

 *--------------------------------------------------------------------*
 | 1      9      6      | 2      4      7      | 3      5      8      |
 | 8      2      7      | 3      5      1      | 4      6      9      |
 | 3      4      5      | 68     9      68     | 27     27     1      |
 *----------------------+----------------------+----------------------|
 | 7      8      24     | 1      6      459    | 29     3      25     |
 | 5      6      1      | 89     2      3      | 89     4      7      |
 | 9      3      24     | 578    78     458    | 1      28     256    |
 *----------------------+----------------------+----------------------|
 | 6      7      89     | 589    3      2589   | 2589   1      4      |
 | 4      5      3      | 6789   1      2689   | 26789  2789   26     |
 | 2      1      89     | 4      78     56     | 56     789    3      |
 *--------------------------------------------------------------------*


[RSW]

Code: Select all

 +---------+--------------+-----------+
 | 1 9  6  | 2    4   7   | 3   5   8 |
 | 8 2  7  | 3    5   1   | 4   6   9 |
 | 3 4  5  | 68   9   68  | 27  27  1 |
 +---------+--------------+-----------+
 | 7 8  24 | 1    6   49  | 29  3   5 |
 | 5 6  1  |e89   2   3   |f89  4   7 |
 | 9 3  24 | 578 d78 458  | 1   28  6 |
 +---------+--------------+-----------+
 | 6 7 a89 | 589  3   2   | 5-8 1   4 |
 | 4 5  3  | 6789 1   689 | 678 789 2 |
 | 2 1 b89 | 4   c78  56  | 56  789 3 |
 +---------+--------------+-----------+


X-Chain (8)r7c3=r9c3-r9c5=r6c5-r5c4=r5c7 => -8r7c7 ste
At first I thought this was the same solution as Leren's finned swordfish, just represented as an X-Chain, but it is different.

[Leren]

RSW wrote : X-Chain (8)r7c3=r9c3-r9c5=r6c5-r5c4=r5c7

You can call it a Sashimi Finned XWing in abcd with fin transport def. Leren

[Cenoman]

Two other techniques:

Code: Select all

 +-----------------+--------------------+-------------------+
 |  1    9    6    |  2      4    7     |  3     5     8    |
 |  8    2    7    |  3      5    1     |  4     6     9    |
 |  3    4    5    |  68     9    68    |  27    27    1    |
 +-----------------+--------------------+-------------------+
 |  7    8    24   |  1      6    49    | b29    3     5    |
 |  5    6    1    |  89     2    3     | b89    4     7    |
 |  9    3    24   | a578   a78   458   |  1    a28    6    |
 +-----------------+--------------------+-------------------+
 |  6    7    89   |  89-5   3    2     | b58    1     4    |
 |  4    5    3    |  6789   1    689   |  678   789   2    |
 |  2    1    89   |  4      78   56    |  56    789   3    |
 +-----------------+--------------------+-------------------+

ALS-XZ rule: (5=782)r6c458 - (2=895)r457c7 => -5 r7c4; ste

or uniqueness technique:

Code: Select all

 +-----------------+--------------------+-------------------+
 |  1    9    6    |  2      4    7     |  3     5     8    |
 |  8    2    7    |  3      5    1     |  4     6     9    |
 |  3    4    5    |  68*    9    68*   |  27    27    1    |
 +-----------------+--------------------+-------------------+
 |  7    8    24   |  1      6    49    |  29    3     5    |
 |  5    6    1    |  89     2    3     |  89    4     7    |
 |  9    3    24   |  578    78   458   |  1     28    6    |
 +-----------------+--------------------+-------------------+
 |  6    7    89*  | b589*   3    2     | c58    1     4    |
 |  4    5    3    | a6789*  1    689*  | d68-7 a789*  2    |
 |  2    1    89*  |  4      78   56    | d56   a789*  3    |
 +-----------------+--------------------+-------------------+

MUG (689)r38c46, r79c3, r7c4, r89c8, using internals
(7)r8c4|r89c8 == (5)r7c4 - r7c7 = (56)r89c7 => -7 r8c7; ste

[SpAce]

RSW wrote : X-Chain (8)r7c3=r9c3-r9c5=r6c5-r5c4=r5c7

You can call it a Sashimi Finned XWing in abcd with fin transport def. Leren

Yeah, if you want to make it as complicated as possible. Finned Mutant Swordfish would do.

[Pupp]

I thought my solution was the simplest.

I'm not even sure what that technique is called.

Why is everybody else trying to make the solution so complicated?

[SpAce]

Hi Pupp,

I thought my solution was the simplest.
I'm not even sure what that technique is called.

I'm sorry to say, but I can't see any valid logic in your solution:

look at r6c3(2,4) as "a", then r6c8(2,8) as "b", then r3c8(2,7) as "c": that means "b"r6c8=8 which is the number that is NOT the common denominator. Also note that the NOT common denominator numbers are all different. So it's 3 different pairs of numbers with a single common denominator number.

Can you explain how those three bivalue cells prove that 8 must be in r6c8?

[Pupp]

Hi Pupp,

I thought my solution was the simplest.
I'm not even sure what that technique is called.

I'm sorry to say, but I can't see any valid logic in your solution:

look at r6c3(2,4) as "a", then r6c8(2,8) as "b", then r3c8(2,7) as "c": that means "b"r6c8=8 which is the number that is NOT the common denominator. Also note that the NOT common denominator numbers are all different. So it's 3 different pairs of numbers with a single common denominator number.

Can you explain how those three bivalue cells prove that 8 must be in r6c8?

I have no idea. I use the technique a lot. Call it the PUPP technique.

One day I was stuck and looked at 3 cells like that, and picked the common denominator and it didn't work. The common denominator seemed like common sense. Out of curiosity, I went back to that point and picked the NOT common denominator and it worked.

[SpAce]

I have no idea. I use the technique a lot. Call it the PUPP technique.

One day I was stuck and looked at 3 cells like that, and picked the common denominator and it didn't work. The common denominator seemed like common sense. Out of curiosity, I went back to that point and picked the NOT common denominator and it worked.

I think we have a name for that technique already, but if you really want your name attached to it, I'm sure it can be arranged

[Pupp]

I have no idea. I use the technique a lot. Call it the PUPP technique.

One day I was stuck and looked at 3 cells like that, and picked the common denominator and it didn't work. The common denominator seemed like common sense. Out of curiosity, I went back to that point and picked the NOT common denominator and it worked.

I think we have a name for that technique already, but if you really want your name attached to it, I'm sure it can be arranged

'
I've been using that technique for weeks, on a very frequent basis. It's long past the guessing stage for me.

Not only that, but at least once, it worked with 3 pencil mark numbers in a cell, where there were 2 common denominators in each of the 3 cells.
-I only came across that particular formation once, so I haven't used it a 2nd time. I'd have to try that several times before I'd consider it a technique, but the logic is basically the same as having 2 pencil mark numbers in a cell.

[SteveG48]

Code: Select all

 *------------------------------------------------------------*
 | 1     9     6     | 2     4     7     |  3     5     8     |
 | 8     2     7     | 3     5     1     |  4     6     9     |
 | 3     4     5     |b68    9     68    |  27    27    1     |
 *-------------------+-------------------+--------------------|
 | 7     8     24    | 1     6     49    |  2-9   3     5     |
 | 5     6     1     |b89    2     3     |ac89    4     7     |
 | 9     3     24    | 578   78    458   |  1     28    6     |
 *-------------------+-------------------+--------------------|
 | 6     7     89    |b589   3     2     |ac58    1     4     |
 | 4     5     3     |b6789  1     689   | c678   789   2     |
 | 2     1     89    | 4     78    56    | c56    789   3     |
 *------------------------------------------------------------*


(9=85)r57c7 - (5=6897)r3578c4 - (7=5689)r5789c7 => -9 r4c7 ; stte

[SpAce]

I've been using that technique for weeks. It's long past the guessing stage for me.

Okay. Let's assume so. Can you give the exact specifications of the pattern so the rest of us could learn to use it? What I see in this case is this:

We have three bivalue cells with one common digit (2) and three other digits (4,8,7) -- one for each cell. One of the three cells (let's call that a pivot cell) sees the other two (via row and column). All three cells are in different boxes. According to you, that pattern somehow proves that the non-common digit (8) can be placed in the pivot cell.

Does that describe your pattern in general, or is there something I'm missing? Is there anything that can be different (like two cells in the same box)?

In other words, you should be able to give me enough information to be able to recognize the same pattern in any puzzle (that has it) and safely execute the placement. Can you do that?