Fred Lunnon writes: << . . . A similar tour based on body-diagonals --- rather than face-diagonals or edges --- is easily seen to be impossible. But exactly why should this be so; and what is the corresponding situation for d-space?

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And what about similar tours in the n-torus R^n / Z^n ? --Dan _____________________________________________________________________ "It don't mean a thing if it ain't got that certain je ne sais quoi." --Peter Schickele