The Omnifarium - Sudoku

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 #40

Category: Sudoku
Wed, 03 Aug 2005, 09:19

First, for those who landed yesterday on Air France flight 358, welcome to Toronto!

During the past weekend, I added some improvements to my Sudoku program to generate puzzles with four-fold symmetry. There are several ways to have puzzles with four-fold symmetry. The first is four-fold rotational symmetry. That is, a puzzle that has the same pattern when rotated 90, 180, or 270 degrees.

There are also a couple of varieties of four-fold mirror symmetry. One type is reflection about both the horizontal and the vertical. Another is reflection about the two diagonals.

Of these types of symmetry, generating puzzles with four-fold rotational symmetry seems the fastest, with puzzles generated only a bit slower than with two-fold rotation symmetry. Mirror symmetry about the two diagonals is slower, and about the vertical and horizontal much slower still.

Todays puzzle features four-fold rotational symmetry. I rather like the appearance of this type of symmetry, so I may be doing more of this style of puzzle.

Hans

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