## Unsolvable for me :not enough knowledge of exotic techniques

Post puzzles for others to solve here.

### Unsolvable for me :not enough knowledge of exotic techniques

Maybe one of you can find a way to break open this puzzle. Hodoku starts to guess.
Code: Select all
`005300000800000020070010500400005300010070006003200080060500009004000030000009700`
urhegyi

Posts: 107
Joined: 13 April 2020

### Re: Unsolvable for me :not enough knowledge of exotic techni

urhegyi wrote:Maybe one of you can find a way to break open this puzzle. Hodoku starts to guess.
Code: Select all
`005300000800000020070010500400005300010070006003200080060500009004000030000009700`

It takes SudokuExplainer 3 minutes to solve this SE = 10.6/1.2/1.2 puzzle. Humans beware!

m_b_metcalf
2017 Supporter

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Location: Berlin

### Re: Unsolvable for me :not enough knowledge of exotic techni

2020-11-16.png (112.49 KiB) Viewed 279 times
This is the output of sudoku explaner 1.17.7:
urhegyi

Posts: 107
Joined: 13 April 2020

### Re: Unsolvable for me :not enough knowledge of exotic techni

urhegyi wrote:Maybe one of you can find a way to break open this puzzle. Hodoku starts to guess.
Code: Select all
`005300000800000020070010500400005300010070006003200080060500009004000030000009700`

Where did you find this puzzle ?
It is rated 10.6 by S.E. Clearly, it is in the "hardest" range. If it is not yet in champagne's "Hardest Data Base", it has to be added.

It seems to have no exotic pattern, but I have not checked whether it has a symmetry. Eleven, Leren: have you looked at symmetries ?
Cenoman
Cenoman

Posts: 1549
Joined: 21 November 2016
Location: Paris, France

### Re: Unsolvable for me :not enough knowledge of exotic techni

125316250_1524407154435823_4197074005435076774_n.jpg (83.38 KiB) Viewed 249 times

It was posted on a sudoku puzzle facebook group where has been asked why B5 on the picture was empty. Till now nobody has answered this question.
There was one person who was claiming he has solved it with his own theory, but refuses to explain how. He gave only the 4 first posted digits without an explanation.(R2C5=5,R5C6=3,R6C1=7,R6C6=6)
urhegyi

Posts: 107
Joined: 13 April 2020

### Re: Unsolvable for me :not enough knowledge of exotic techni

It certainly seems unlikely he would have found those digits in that order, regardless of some exotic technique used - r5c6 is a hidden single to start with, and 7r6c1 gives a couple other singles (which aren't r6c6).
mith

Posts: 339
Joined: 14 July 2020

### Re: Unsolvable for me :not enough knowledge of exotic techni

mith wrote:It certainly seems unlikely he would have found those digits in that order, regardless of some exotic technique used - r5c6 is a hidden single to start with, and 7r6c1 gives a couple other singles (which aren't r6c6).

I'm trying to compare the pencilmarks on the picture with those of sudoku-explainer at the moment, but there seems to be just 1 error on it R7C8<>7 which is not updated as R9C7=7 is a given digit. Did the poster the pencilmarks by hand? Further no reason asking for the empty cell. It's obviously a hidden single. Now finding out why such a hard sudoku was posted on the facebook group, where we can be for hundred percent sure nobody will find a logical solvepath, based on deduction and not on guessing like I think the poster of the 4 digits he claimed to have found did.
urhegyi

Posts: 107
Joined: 13 April 2020

### Re: Unsolvable for me :not enough knowledge of exotic techni

urhegyi wrote:why B5 on the picture was empty.

The image showing 'Candidate Editing via the keyboard is active' highlighted on a red background - I assume someone was trying to make the puzzle easier/harder.
B8=2 color is different from the other givens - Maybe original layout was different, which could explain the missing pencilmarks.
1to9only

Posts: 2127
Joined: 04 April 2018

### Re: Unsolvable for me :not enough knowledge of exotic techni

urhegyi wrote:Maybe one of you can find a way to break open this puzzle. Hodoku starts to guess.
Code: Select all
`005300000800000020070010500400005300010070006003200080060500009004000030000009700`

I didn't raise my question clearly enough in my previous post.

Is this puzzle in the "Potential Hardest Sudokus" data base ?
Cenoman
Cenoman

Posts: 1549
Joined: 21 November 2016
Location: Paris, France

### Re: Unsolvable for me :not enough knowledge of exotic techni

Cenoman wrote:
urhegyi wrote:Maybe one of you can find a way to break open this puzzle. Hodoku starts to guess.
Code: Select all
`005300000800000020070010500400005300010070006003200080060500009004000030000009700`

I didn't raise my question clearly enough in my previous post.

Is this puzzle in the "Potential Hardest Sudokus" data base ?

It can not be, the filter requires a pearl at the 10.6 level.

I know that the filter in the bottom part of the PH data base could be discussed, but this is true only for puzzles with an ED <10.7. When the data base was started, the focus was (and still is in some ways) on puzzles with an ED >11.0

Note : It could be in my data base of seeds (or in a similar database of those having searched puzzles with high rating)s.
champagne
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Location: France Brittany

### Re: Unsolvable for me :not enough knowledge of exotic techni

champagne wrote:
Cenoman wrote:Is this puzzle in the "Potential Hardest Sudokus" data base ?

It can not be, the filter requires a pearl at the 10.6 level.

I know that the filter in the bottom part of the PH data base could be discussed, but this is true only for puzzles with an ED <10.7. When the data base was started, the focus was (and still is in some ways) on puzzles with an ED >11.0

Note : It could be in my data base of seeds (or in a similar database of those having searched puzzles with high rating)s.

Thanks champagne !
I didn't know what a pearl is, so I have searched on the forum. If I catch it correctly, this puzzle is not a pearl because it has two hidden singles, and the puzzle with +5r2c5 and +3r5c6 neither, because it's not minimal. Anyhow after these two placements and possible other basic moves, the puzzle is hard to solve. So my next question to you is:

Is your solver able to solve it without any brute force step ?
Mine is not, and YZF_Solver neither. Not tried XSudo yet...
Cenoman
Cenoman

Posts: 1549
Joined: 21 November 2016
Location: Paris, France

### Re: Unsolvable for me :not enough knowledge of exotic techni

Cenoman wrote:
champagne wrote:
Cenoman wrote:Is this puzzle in the "Potential Hardest Sudokus" data base ?

Is your solver able to solve it without any brute force step ?
Mine is not, and YZF_Solver neither. Not tried XSudo yet...

Sudoku Explainer has no "brute force" step, so

Sudoku Explainer will deliver an ugly net for the 10.6 step
skfr will do something similar

I have some doubts for my last version of the solver because, so far, I did not implement the last levels of Sudoku Explainer, and, as far as I remember, the ceiling in ratings is more in the 9.2 to 9.7 but I can be wrong.

To day, I am 100% working (for the time dedicated to the sudoku) on an attempt to speed up my 17 clues search.
champagne
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Joined: 02 August 2007
Location: France Brittany

### Re: Unsolvable for me :not enough knowledge of exotic techni

Cenoman wrote:I didn't know what a pearl is,

A diamond has an SE rating of the form x/x/x (x> 2.3). A pearl's rating is of the form x/y/z, for x > 2.3, y <= x, 2.3 < z < x. E.g. 9.0/9.0/9.0 is a diamond and 9.0/9.0/2.6 is a pearl.

HTH

Mike

m_b_metcalf
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### Re: Unsolvable for me :not enough knowledge of exotic techni

m_b_metcalf wrote:A diamond has an SE rating of the form x/x/x (x> 2.3). A pearl's rating is of the form x/y/z, for x > 2.3, y <= x, 2.3 < z < x. E.g. 9.0/9.0/9.0 is a diamond and 9.0/9.0/2.6 is a pearl.
HTH
Mike

Thank you Mike. I have seen this form of rating, notably in list of hard puzzles.
May I ask further help ?
What do the Letters "ED" stand for, in a rating ?
What exactly is rated by each of the three numbers x/y/z ?
Where could I download an SE version rating this way (I'm still using SE 1.2.1) ?

The threads dealing with this are now so diluted that they are discouraging... A link to a relevant post would be appreciated.
Cenoman
Cenoman

Posts: 1549
Joined: 21 November 2016
Location: Paris, France

### Re: Unsolvable for me :not enough knowledge of exotic techni

Cenoman wrote:What do the Letters "ED" stand for, in a rating ?
What exactly is rated by each of the three numbers x/y/z ?
Where could I download an SE version rating this way (I'm still using SE 1.2.1) ?

You can look here for starters.

Mike

m_b_metcalf
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Posts: 11320
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Location: Berlin