> missing information is rather anathema to science ... Date and Darwen and
others have demonstrated serious problems with NULL, 3-VL, 4-VL and "n-VL
as n approaches infinity" even when applied consistently.
They are correct.
> ... missing information is a difficult problem no matter what data model
one uses. We currently have no theory regarding missing information which
means we have no theory to overcome the practical problem in any data
model.
In the experimental data model (which I haven't described in any detail
and not inclined to do so currently), a NULL can not occur for missing
information. This can be verified with the actual experimental db
executable. If someone would like to verify this, please post the
situation under which you think it would and we can test it. (And if
one thinks this is because the data is stored willy-nilly, we can
verify it isn't by performing some queries).
