Double Sudoku

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Double Sudoku

Postby kakuroatk » Wed Jun 09, 2021 6:00 pm

Here is a double sudoku that encompasses 2 9x9 overlapping sudokus:

Image

This puzzle can be playable online here: https://www.atksolutions.com/games/sudoku.html
and the puzzle # is H50242 which can be entered by clicking the pencil/paper icon on the main screen.
It is a hard level puzzle.

This puzzle may have some unique strategies due to the symmetry.
kakuroatk
 
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Re: Double Sudoku

Postby Hajime » Thu Jun 10, 2021 8:04 am

kakuroatk wrote:Here is a double sudoku that encompasses 2 9x9 overlapping sudokus


Yeap, this is a nasty one and there are methods needed like forcing chains or forcing nets (I think) which leads to the environment of guessing.
SiSeSuSo could only solve this with some forcing nets and an estimated SER=9.6
Code: Select all
+--------+--------+--------+           
|        |       2| 5     6|           
| 7  1   |        |    8   |           
|        |        |        |           
+--------+--------+--------+--------+ 
|       9|        | 4      | 8     1| 
|    7   |        |        |    3   | 
|       5|    8   |       3|        | 
+--------+--------+--------+--------+ 
|        | 2      |    5   | 4      | 
|    9   |        |        |    1   | 
| 5     2|       9|        | 5      | 
+--------+--------+--------+--------+ 
         |        |        |        | 
         |    6   |        |    2  9| 
         | 8     7| 3      |        | 
         +--------------------------+ 
                                       
#2//B4/E10
.....25.671.....8............9...4...7.........5.8...3...2...5..9.......5.2..9...
...4..8.1.......3..8...3...2...5.4.........1...9...5............6.....298.73.....

The solution is:
Hidden Text: Show
Code: Select all
9 3 4 8 1 2 5 7 6       
7 1 6 5 9 4 3 8 2       
2 5 8 3 6 7 9 4 1       
1 8 9 7 2 3 4 6 5 8 9 1
6 7 3 9 4 5 2 1 8 6 3 7
4 2 5 6 8 1 7 9 3 2 4 5
8 4 7 2 3 6 1 5 9 4 7 8
3 9 1 4 5 8 6 2 7 9 1 3
5 6 2 1 7 9 8 3 4 5 6 2
      5 1 2 9 7 6 3 8 4
      3 6 4 5 8 1 7 2 9
      8 9 7 3 4 2 1 5 6
but normally no one is interested in the solution, but in the path that leads to it.
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Hajime
 
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Re: Double Sudoku

Postby kakuroatk » Thu Jun 10, 2021 1:45 pm

Thank you for the feedback.

SiSeSuSo could only solve this with some forcing nets and an estimated SER=9.6


I never even knew about the SiSeSuSo solver. I will look it up. Is SiSeSuSo also giving the SER value or is that calculated another way?

but normally no one is interested in the solution, but in the path that leads to it.


I agree 100%, it is the path to the solution that is important, but I think there are always several approaches based on your method of solving and/or the type solver.

I will try to create a way to show a visual solution path to this puzzle and others (like a PDF)
It will take an another extended project for me to do this but I have an idea.
kakuroatk
 
Posts: 27
Joined: 17 September 2013
Location: NY

Re: Double Sudoku

Postby Hajime » Thu Jun 10, 2021 3:41 pm

kakuroatk wrote: I never even knew about the SiSeSuSo solver. I will look it up. Is SiSeSuSo also giving the SER value or is that calculated another way?

It can be downloaded here https://sites.google.com/site/sisesuso
and it is mentioned in your previous post http://forum.enjoysudoku.com/mini-quad-sudoku-t38973.html#p303354, but not it's capabilities.
The SER is estimated because SiSeSuSo is not solving the path like SudokuExplainer all the times, and not all solving techniques are implemented (yet).
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Hajime
 
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Re: Double Sudoku

Postby kakuroatk » Thu Jun 24, 2021 6:54 pm

Here is a visual step by step solution for this puzzle #H50242

http://www.atksolutions.com/games/variations/solution-H50242.pdf

color key:
blue - givens
green - solved cells
red - pencil marks
dark blue - changes in the cell from previous step
light pink - constraint with a hidden single
light yellow - constraint with a double, triple, quad, hidden double, hidden triple, hidden quad
light blue - affected constraint(s) when testing the removed pencilmark(s) from the previous step.
(you can see pencilmarks shown in dark blue, look at the previous step to see what pencilmark was removed and if had you tested it instead, it would lead to a duplicate issue with the involved constraints shown in light blue)

LMK if you have any questions.
kakuroatk
 
Posts: 27
Joined: 17 September 2013
Location: NY


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