I found this on
www.sudokufun.com - I used the print function to get a hard copy, and there is no category or any other identification.
If there is a category, I wish I knew how to find out. What are the choices of categories?
After about 20 hours, I went back to work on this, and I found that I had missed 2 "easy" 6's, in box 2 (as you pointed out), which leads to another in box 5. I now have:
*** *** 5*9
1*5 2** *68
78* *56 *2*
**6 *** 8*7
*2* 1*8 *56
5*8 *6* 2**
*4* 93* *85
85* 6*7 9*4
9** *** **2
I haved solved this by trial and error, so I have "the" answer. This is how I discovered I had missed the two "easy" 6's.
I have put the pencil numbers in every square. I am trying hard to see how this can be solved using logic, and I still cannot do it.
Once again, any help will be much appreciated.