From Ken Zetie
Netropolitan remarks that three-dimensional crosswords have proven difficult
to construct
(10 June, p 17).
Half a century ago, Claude Shannon commented on
this very fact in his classic papers on information theory.
He pointed out that English words have a redundancy of approximately 50 per
cent—meaning that about half of the letters are unnecessary to guess each
word. This is ideal for 2D crosswords as it allows the setter a reasonable
choice of words, even when the grid starts to fill.
Too much redundancy—too many unnecessary letters—and the choice
is limited, leaving large gaps in the grid. Too little redundancy and solving
one clue does not help solve the words it crosses. To make 3D crosswords easy to
set you require a language with 33 per cent redundancy.
London
