A cool algorithm to check a Sudoku field?

Question

Does anyone know a simple algorithm to check if a Sudoku-Configuration is valid? The simplest algorithm I came up with is (for a board of size n) in Pseudocode

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Answer 1

Here is paper by math professor J.F. Crook: A Pencil-and-Paper Algorithm for Solving Sudoku Puzzles

This paper was published in April 2009 and it got lots of publicity as definite Sudoku solution (check google for "J.F.Crook Sudoku" ).

Besides algorithm, there is also a mathematical proof that algorithm works (professor admitted that he does not find Sudoku very interesting, so he threw some math in paper to make it more fun).