16 Feb 2006

[David Bryant]

I really like this puzzle, Ruud!

With 50 of the cells resolved and 31 still to go I reached a position that contains a lot of {2, 5} pairs. There are 3 unresolved instances of the digit "4" at this stage of the puzzle, and those can be entered in two different ways.

Analysis of the "remote pairs" of {2, 5} that would exist either way the "4"s are placed leads one to place a couple of "9"s. Further analysis of the chain of {2, 5} pairs then proves that only one of the placements of the "4"s is possible. Now we can chase the {2, 5} pairs in earnest, and finally crack the puzzle wide open!

Did someone find a different way to solve it? dcb