This is a response to ZD’s and udosuk’s posts and progress updates regarding solving the puzzle posted on September 27 by hand and using logic. This is how far we got – I added “9” in the last nonet as ZD suggested. From ZD’s and udosuk’s work you can also find some of the pencilmarks that can be removed from this position. Their discussion is
here
If you’d like to work on this, you can open this file in any image editor (say Microsoft’s “Paint”) and delete “pencil marks” (using simple tools of your imaging software) when you figure out which values can be removed.
One suggestion – if you solve R9C1 and R1C9 the solution should unfold somewhat easier. I’m not saying this is the next logical step; I only figured that if those 2 were solved there would be no more “trial and error” needed to solve this one.
Good luck!
