The New Sudoku Players' Forum

[swaatacba]

This puzzle is taken from 7Sudku and is rated very difficult. At any rate I cannot get beyond the image below, other than by guess work.

https://drive.google.com/file/d/1hOkQ570W4Y8sn7L_n54sqpW5pZvvFf_C/view?usp=sharing

Can someone offer a rational arguement for the next step. (Sorry about the need to click on the url, but I have run out of image space.)

[jco]

Hello swaatacba,

It would be nice if you could provide either a link with open access (that one needs approval)
or the following grid filled out with your configuration (*).

Code: Select all

.-----------------------------.
| .  .  . | .  .  . | .  .  . |
| .  .  . | .  .  . | .  .  . |
| .  .  . | .  .  . | .  .  . |
|---------+---------+---------|
| .  .  . | .  .  . | .  .  . |
| .  .  . | .  .  . | .  .  . |
| .  .  . | .  .  . | .  .  . |
|---------+---------+---------|
| .  .  . | .  .  . | .  .  . |
| .  .  . | .  .  . | .  .  . |
| .  .  . | .  .  . | .  .  . |
'-----------------------------'

Regards,
JCO

PS: (*) just copy the grid above into a text editor, fill it out, and then,
after choosing "post a reply", paste the grid, using "code" to preserve
the original format.

[swaatacba]

It would be nice if you could provide either a link with open access (that one needs approval)

I have amended the link such that anyone can download the image.

The possibility of converting my Excel file into your grid configuration is one I am still working on. Filling it out by hand is prone to a error. In this context, I must avoid that.

Stephen

[jco]

Hi Stephen,

Looking at the picture, in column 7 there is only one place a 7 can go: r2c7=7.
You have locked candidates (digit 9) in row 2, columns 8,9 (block 3).
So, either r2c8=9 or r2c9=9. That eliminates other 9s from that block.
You also have locked candidates (again in the digit 9) in block 6. That
eliminates more 9s from that block.
After this you have only singles to find to the end.

Regards,
JCO

[swaatacba]

Thank you. How could I possibly have missed that!

Something to do with marking ones own homework.

Stephen