Ok, I see.
This is the case where the closure has only one more cell than the initial puzzle.
For the creator of this type of puzzle, I guess it's about finding the maximum SER for the placement.
JPF
Just One Cell
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Re: Just One Cell
by JPF » Mon Aug 23, 2021 7:14 pm
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Re: Just One Cell
by m_b_metcalf » Tue Aug 24, 2021 12:15 pm
yzfwsf wrote:This Sudoku variant cannot use UR or any technology that relies on unique solutions to puzzles.
... such as the backdoor 6r2c6.
Mike
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Re: Just One Cell
by yzfwsf » Tue Aug 24, 2021 12:36 pm
m_b_metcalf wrote:... such as the backdoor 6r2c6.
Mike
I don’t quite understand what you want to explain, but the solution to this puzzle is r3c2=7.
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Re: Just One Cell
by m_b_metcalf » Tue Aug 24, 2021 2:36 pm
yzfwsf wrote:m_b_metcalf wrote:... such as the backdoor 6r2c6.
Mike
I don’t quite understand what you want to explain, but the solution to this puzzle is r3c2=7.
I'm simply agreeing that you can't use solving techniques based on uniqueness. Backdoors rely on that, and I find two in this puzzle, the other being 8r3c9.
Regards,
Mike
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Re: Just One Cell
by yzfwsf » Tue Aug 24, 2021 3:16 pm
m_b_metcalf wrote:I'm simply agreeing that you can't use solving techniques based on uniqueness. Backdoors rely on that, and I find two in this puzzle, the other being 8r3c9.
For your research, I don't understand. I just wrote a puzzle generator according to the rules of this puzzle variant. This puzzle is randomly generated by the generator. Just find the only cell with a unique solution.
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Re: Just One Cell
by denis_berthier » Tue Aug 24, 2021 3:47 pm
m_b_metcalf wrote:Backdoors rely on that (uniqueness)
It depends on how you define a backdoor.
In my view, it's any candidate that, when added to the givens, allows to find a solution using only Singles.
As a result, in case of non-uniqueness, different backdoors can lead to different solutions. However, I'm not sure the notion of a backdoor is very useful in this case.
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Re: Just One Cell
by m_b_metcalf » Tue Aug 24, 2021 4:33 pm
denis_berthier wrote:It depends on how you define a backdoor.
In my view, it's any candidate that, when added to the givens, allows to find a solution using only Singles.
As a result, in case of non-uniqueness, different backdoors can lead to different solutions. However, I'm not sure the notion of a backdoor is very useful in this case.
On that strict definition only the second one I find is a true backdoor. But both lead to the same solution, DEFISE's number 161.
Regards,
Mike
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Re: Just One Cell
by m_b_metcalf » Tue Aug 24, 2021 5:06 pm
Last edited by m_b_metcalf on Tue Aug 24, 2021 6:35 pm, edited 1 time in total.
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Re: Just One Cell
by denis_berthier » Tue Aug 24, 2021 6:35 pm
m_b_metcalf wrote:denis_berthier wrote:It depends on how you define a backdoor.
In my view, it's any candidate that, when added to the givens, allows to find a solution using only Singles.
As a result, in case of non-uniqueness, different backdoors can lead to different solutions. However, I'm not sure the notion of a backdoor is very useful in this case.
On that strict definition only the second one I find is a true backdoor. But both lead to the same solution, DEFISE's number 161.
What is your looser definition?
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Re: Just One Cell
by m_b_metcalf » Tue Aug 24, 2021 6:38 pm
denis_berthier wrote:What is your looser definition?
My program can allow other simple techniques apart from singles, but I can switch that off. M.
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Re: Just One Cell
by denis_berthier » Wed Aug 25, 2021 1:15 am
m_b_metcalf wrote:denis_berthier wrote:What is your looser definition?
My program can allow other simple techniques apart from singles, but I can switch that off. M.
I see. I can do this also. But then I qualify them as W1-backdoors, S-Backdoors....
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Re: Just One Cell
by m_b_metcalf » Wed Aug 25, 2021 12:36 pm
It turns out that these puzzles can be generated in great profusion (see my previous post with 106 examples). Here are two more that
are symmetric and have very many solutions (but, of course, with one empty cell having the same value in all of them - the object of the search).
I have another 1000 symmetric puzzles on file.
Regards,
Mike
are symmetric and have very many solutions (but, of course, with one empty cell having the same value in all of them - the object of the search).
I have another 1000 symmetric puzzles on file.
Regards,
Mike
- Code: Select all
. . . . . 9 . . 1
. 3 . . . . . 2 .
. . 5 6 8 . . . .
. . 4 . . 8 7 . .
. . 6 . . . . . .
1 . . 4 . . . . .
. . . 7 . . 5 . .
. 4 . . . . . 6 .
2 . . . . . . . 8 Diagonal symmetry, no. of givens = 19.
.....9..1.3.....2...568......4..87....6......1..4........7..5...4.....6.2.......8
- Code: Select all
. . . . . . . 2 .
. . . . . 9 . 7 3
. . 8 . 5 . . . .
. . . 4 . . . 6 .
. . 5 . . . 4 . .
. 1 . . . 2 . . .
. . . . 8 . 3 . .
6 2 . 1 . . . . .
. 3 . . . . . . . Rotational symmetry, no. of givens = 18.
.......2......9.73..8.5.......4...6...5...4...1...2.......8.3..62.1......3.......
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Re: Just One Cell
by yzfwsf » Thu Aug 26, 2021 3:50 am
Hi Mike!
How did you make these puzzles. I use the following generation method, first find a suitable pear puzzle, and then use the traditional top-down method.
Regards,
YZF
How did you make these puzzles. I use the following generation method, first find a suitable pear puzzle, and then use the traditional top-down method.
Regards,
YZF
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Re: Just One Cell
by m_b_metcalf » Thu Aug 26, 2021 7:34 am
yzfwsf wrote: How did you make these puzzles. I use the following generation method, first find a suitable pear puzzle, and then use the traditional top-down method.
Step 1: Generate, or copy, a file of puzzles guaranteed to be minimal (hint: Patterns Game).
Step 2: From such a puzzle remove one clue - the puzzle now has multiple solutions.
Step 3: Find all those solutions whilst keeping a running tally of their common values.
Step 4: If the number of common values less the number of givens is 1, save the modified puzzle to a file.
Repeat from 2.
HTH
Mike
P.S. I'm not sure what you mean by 'suitable pear puzzle'.
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Re: Just One Cell
by yzfwsf » Thu Aug 26, 2021 8:16 am
I mean to find the pearl puzzle of the difficulty specified by the user.
The way I check whether the puzzle is just one cell is also different from yours. I traverse the pencil mark of each cell to blast the pruning, so I don’t need to get all the solutions.
YZF
The way I check whether the puzzle is just one cell is also different from yours. I traverse the pencil mark of each cell to blast the pruning, so I don’t need to get all the solutions.
YZF
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