In asking "Arnie" to explain the logic of where a number goes in row 8 of "HopDunne's unsolved puzzle (June 28), I can follow "Simes" logic that "There's only one cell (sic. column 7) in row 8 that can contain a 7". However, as 7 is also a candidate in four cells in row 7 (columns 2,4,7 and 8) and also a candidate in another three cells in row 9 (columns 2,4 and 7) I still don't understand why 7 must go in row 8 when it is also a candidate for other cells in rows 7 or 9 as mentioned above.
I don't know if "HopDunne", who instigated this puzzle, can follow the explanations given but I am still confused in advancing further with this puzzle even if it doesn't have a solution. I am greatful for the feedback from other members to this intriguing sudoku and wish to remove my frustration when I can't understand the explanations given.
Regards again, Bonsai Cec