Place the letters A-I in the cells so that each row contains exactly one of
each letter. Ditto for each column and for each region.

How To Solve a Du-Sum-Oh Puzzle

These two 9x9’s can be solved without trial and error.

**Warning!** I don't think the following 9x9 puzzles can be
easily solved without the use of a computer. They are interesting mathematical
curiosities, having been the first *non-trivial* 8-hint 9x9’s
discovered (as far as this author is aware). See the
proof
about N-1 hint puzzles for more information about this claim.

Back to Bob’s main Du-Sum-Oh page.