The Omnifarium - Sudoku/14.html

Notice

I am no longer posting new puzzles to this blog. For all of my Sudoku puzzles, old and new, please visit Sudoku in another section of this website. I will still create and offer new puzzles, in batches of a couple of hundred, once a week or so.

Sudoku #14

Category: Sudoku
Mon, 04 Jul 2005, 09:15

In #10, #11, and #12 I discussed some basic and advanced Sudoku solving techniques. Here is one more advanced method. Unlike the others, this one requires looking at two groups at once.

Look at the intersection of a 3x3 square (call it set A) and either a row or a column (call it set B). There are three cells in the intersection, which we'll call set C. (That is, C=A∩B.) For this method to work, there must be at least two unknown cells in the intersection.

Now then, if some possibility x exists in set C but not in A-C, then that possibility also cannot exist in B-C. That is, possibility x can then be eliminated from the cells of B not part of the intersection. And of course, vice versa.

Are there any other easy analytical methods? So far, I've only found one published puzzle that can't be solved by some combination of these basic and advanced techniques. I've found one more advanced techique, but I won't discuss it until I can come up with an easy way to describe it. For now though, none of the puzzles I've posted so far need that particular technique.

Anyways, for today, you get a slightly easier puzzle.

Hans

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