Abstract:
A completed sudoku puzzle is a Latin square of order 9 with
the additional condition that each symbol appears exactly once in each
of the 3\times 3 `blocks'. Two sudoku puzzles are orthogonal if the
set of ordered pairs of symbols formed by the superimposition of the
puzzles is exhaustive. In the presentation we explore a variety of
methods for creating pairs of orthogonal puzzles. Along the way we
also consider the question of whether two orthogonal puzzles are
`essentially the same' in the sense that both puzzles lie in the same
orbit of a symmetry group.
