The New Sudoku Players' Forum

[JPF]

Code: Select all

 1 . . . 2 . . . 3
 . . . 3 . . . 4 .
 . . 5 . . . 6 . .
 . 7 . . . 8 . . .
 2 . . . . . . . 5
 . . . 4 . . . 2 .
 . . 4 . . . 8 . .
 . 8 . . . 7 . . .
 3 . . . 5 . . . .    ER 8.3



JPF

[Mauricio]

I have no choice.

Code: Select all

1 . .|. 2 .|. . 3
. . .|3 . .|. 4 .
. . 4|. . .|5 . .
-----+-----+-----
. 6 .|. . 4|. . .
5 . .|. . .|. . 1
. . .|7 . .|. 2 .
-----+-----+-----
. . 8|. . .|6 . .
. 9 .|. . 5|. . .
3 . .|. 1 .|. . .    ER 8.6


[Mauricio]

Seven days.

I was about to give up my right to post a new puzzle and give it to someone else, until I had a not so bad idea for a new pattern (I hope it is original).

Code: Select all

1 . .|. . .|. . 2
. 3 .|4 . 5|. 1 .
. . .|. . .|6 . .
-----+-----+-----
. . 4|. . .|7 . .
. . .|1 . 2|. . .
. . 6|. . .|8 . .
-----+-----+-----
. . 8|. . .|. . .
. 4 .|7 . 1|. 3 .
9 . .|. . .|. . 7    ER 1.5


Let's see how hard can they get.

[JPF]

Seven days.

Congratulations
Was 8.6 your best shot ?

I was about to give up my right to post a new puzzle and give it to someone else, until I had a not so bad idea for a new pattern (I hope it is original).

I think we should try to give all the possible SE ratings...

Anyway, here's my first contribution :

Code: Select all

 1 . . | . . . | . . 2
 . 3 . | 4 . 5 | . 6 .
 . . . | . . . | 7 . .
-------+-------+-------
 . . 7 | . . . | 8 . .
 . . . | 3 . 6 | . . .
 . . 2 | . . . | 1 . .
-------+-------+-------
 . . 4 | . . . | . . .
 . 5 . | 8 . 4 | . 9 .
 7 . . | . . . | . . 3      ER=2.0



JPF

[m_b_metcalf]

Anyway, here's my first contribution :

And mine:

Code: Select all

 6 . . . . . . . 2
 . 3 . 9 . 5 . 4 .
 . . . . . . 7 . .
 . . 7 . . . 6 . .
 . . . 1 . 3 . . .
 . . 2 . . . 9 . .
 . . 4 . . . . . .
 . 1 . 8 . 4 . 9 .
 7 . . . . . . . 3 SE 6.6


Regards,

Mike Metcalf

[JPF]

I think we should try to give all the possible SE ratings...

Code: Select all

 1 . . | . . . | . . 2
 . 3 . | 4 . 5 | . 6 .
 . . . | . . . | 7 . .
-------+-------+-------
 . . 7 | . . . | 1 . .
 . . . | 3 . 8 | . . .
 . . 2 | . . . | 9 . .
-------+-------+-------
 . . 4 | . . . | . . .
 . 5 . | 1 . 9 | . 3 .
 6 . . | . . . | . . 5   ER=2.5



and

Code: Select all

 1 . . | . . . | . . 2
 . 3 . | 1 . 4 | . 5 .
 . . . | . . . | 6 . .
-------+-------+-------
 . . 6 | . . . | 7 . .
 . . . | 3 . 8 | . . .
 . . 2 | . . . | 8 . .
-------+-------+-------
 . . 7 | . . . | . . .
 . 4 . | 9 . 7 | . 3 .
 2 . . | . . . | . . 1   ER=6.7



JPF

[m_b_metcalf]

and

and

Code: Select all

 9 . . . . . . . 2
 . 3 . 9 . 5 . 6 .
 . . . . . . 7 . .
 . . 7 . . . 4 . .
 . . . 3 . 8 . . .
 . . 2 . . . 8 . .
 . . 9 . . . . . .
 . 1 . 8 . 4 . 5 .
 7 . . . . . . . 3   SE 7.2


Regards,

Mike Metcalf

[Mauricio]

Was 8.6 your best shot ?

Yes, it was my best of just 56 of such puzzles, that pattern was very tough. The new patterm I proposed it is easier to find than I thought, that will make it easier to newcomers.

Code: Select all

1 . .|. . .|. . 2
. 3 .|4 . 5|. 6 .
. . .|. . .|7 . .
-----+-----+-----
. . 4|. . .|5 . .
. . .|6 . 3|. . .
. . 2|. . .|8 . .
-----+-----+-----
. . 8|. . .|. . .
. 5 .|9 . 1|. 3 .
6 . .|. . .|. . 7     ER7.3


[JPF]

Code: Select all

 
 1 . . | . . . | . . 2
 . 3 . | 2 . 4 | . 5 .
 . . . | . . . | 6 . .
-------+-------+-------
 . . 6 | . . . | 1 . .
 . . . | 7 . 3 | . . .
 . . 8 | . . . | 9 . .
-------+-------+-------
 . . 1 | . . . | . . .
 . 7 . | 5 . 2 | . 3 .
 8 . . | . . . | . . 9   ER=7.6



JPF

[re'born]

Code: Select all

 
 1 . . | . . . | . . 2
 . 3 . | 2 . 4 | . 5 .
 . . . | . . . | 6 . .
-------+-------+-------
 . . 6 | . . . | 1 . .
 . . . | 7 . 3 | . . .
 . . 8 | . . . | 9 . .
-------+-------+-------
 . . 1 | . . . | . . .
 . 7 . | 5 . 2 | . 3 .
 8 . . | . . . | . . 9   ER=7.6



JPF

JPF,

You should submit this puzzle to the Bicycle Collection. It is a real beauty. Just write in the pencilmarks and there is a 4-ring bidirectional y-cycle staring you right in the face. After that an xy-wing and an empty rectangle will reduce it to a BUG+1. Fantastic.

[Mauricio]

Code: Select all

1 . .|. . .|. . 2
. 3 .|4 . 1|. 5 .
. . .|. . .|6 . .
-----+-----+-----
. . 4|. . .|2 . .
. . .|7 . 6|. . .
. . 5|. . .|8 . .
-----+-----+-----
. . 7|. . .|. . .
. 5 .|6 . 9|. 4 .
2 . .|. . .|. . 3    ER 8.3


[Mauricio]

A dealer gives a valid and minimal puzzle solved by singles only ("all singles")
This puzzle must have at least 19 clues, but less than 30.

Each player can post a new valid puzzle provided that his proposed puzzle :

• has the same pattern
• is not an "all singles"
• has a higher ER rating than the preceding posted one.
  

ER is the rating given by Sudoku Explainer 1.2

I wonder why the minimality is not a requisite for the challenging sudokus.

[JPF]

I wonder why the minimality is not a requisite for the challenging sudokus.

Good point.

This one is minimal, anyway :

Code: Select all

 1 . . | . . . | . . 2
 . 3 . | 4 . 5 | . 1 .
 . . . | . . . | 6 . .
-------+-------+-------
 . . 6 | . . . | 7 . .
 . . . | 3 . 2 | . . .
 . . 5 | . . . | 4 . .
-------+-------+-------
 . . 7 | . . . | . . .
 . 8 . | 9 . 1 | . 3 .
 5 . . | . . . | . . 8    ER=8.9



JPF

[claudiarabia]

Code: Select all

 
 1 . . | . . . | . . 2
 . 3 . | 2 . 4 | . 5 .
 . . . | . . . | 6 . .
-------+-------+-------
 . . 6 | . . . | 1 . .
 . . . | 7 . 3 | . . .
 . . 8 | . . . | 9 . .
-------+-------+-------
 . . 1 | . . . | . . .
 . 7 . | 5 . 2 | . 3 .
 8 . . | . . . | . . 9   ER=7.6



JPF

JPF,

You should submit this puzzle to the Bicycle Collection. It is a real beauty. Just write in the pencilmarks and there is a 4-ring bidirectional y-cycle staring you right in the face. After that an xy-wing and an empty rectangle will reduce it to a BUG+1. Fantastic.

Hi, re-born!
another cycle-fan here. I never heared or red of a 4-ring bi-directional y-cycle. It sounds very refined. Is there an explanation in this forum or will you, if it is not so, explain here on this example for the first time, what a 4-ring bi-directional y-cycle is, please? If it would include four cells only, it wouldn't justify the high rating of 7,6 I suppose. So I'm curious.

Claudia

[re'born]

Code: Select all

 
 1 . . | . . . | . . 2
 . 3 . | 2 . 4 | . 5 .
 . . . | . . . | 6 . .
-------+-------+-------
 . . 6 | . . . | 1 . .
 . . . | 7 . 3 | . . .
 . . 8 | . . . | 9 . .
-------+-------+-------
 . . 1 | . . . | . . .
 . 7 . | 5 . 2 | . 3 .
 8 . . | . . . | . . 9   ER=7.6



JPF

JPF,

You should submit this puzzle to the Bicycle Collection. It is a real beauty. Just write in the pencilmarks and there is a 4-ring bidirectional y-cycle staring you right in the face. After that an xy-wing and an empty rectangle will reduce it to a BUG+1. Fantastic.

Hi, re-born!
another cycle-fan here. I never heared or red of a 4-ring bi-directional y-cycle. It sounds very refined. Is there an explanation in this forum or will you, if it is not so, explain here on this example for the first time, what a 4-ring bi-directional y-cycle is, please? If it would include four cells only, it wouldn't justify the high rating of 7,6 I suppose. So I'm curious.

Claudia

Hi Claudia, my definition of a 4-ring bidirectional y-cycle comes from the Bicycle Collection's first post. In this case, after performing zero moves, the pencilmark grid is:

Code: Select all

*--------------------------------------------------------------------------------------*
 | 1        45689    4579     | 3689     356789   56789    | 3478     4789     2        |
 | 679      3        79*      | 2        16789    4        | 78*      5        178      |
 | 24579    24589    24579    | 1389     135789   15789    | 6        14789    13478    |
 |----------------------------+----------------------------+----------------------------|
 | 234579   2459     6        | 489      24589    589      | 1        2478     34578    |
 | 2459     12459    2459     | 7        1245689  3        | 2458     2468     4568     |
 | 23457    1245     8        | 146      12456    156      | 9        2467     34567    |
 |----------------------------+----------------------------+----------------------------|
 | 234569   24569    1        | 34689    346789   6789     | 24578    24678    45678    |
 | 469      7        49*      | 5        14689    2        | 48*      3        1468     |
 | 8        2456     2345     | 1346     13467    167      | 2457     12467    9        |
 *--------------------------------------------------------------------------------------*


and the only 4 bivalued cells form a bidirectional y-cycle. It seems that SE finds this y-cycle, but what drives up the ER is that SE doesn't use the empty rectangle that leads (after an xy-wing) to a BUG+1. Instead, it uses "forcing chains" and "Nishio forcing chains".