Progressive Revelation

Robert A. (Bob) Morris ram at CS.UMB.EDU
Mon Feb 28 11:05:15 CET 2000

Since theology has arisen, how's this: Object oriented databases are
better for this stuff than either hierarchical or relational,
precisely for the reasons you outline below.

[By the way, hoping this is not a forbidden commercialism but at least
reveals my conflict of interest: we operate the university program for
eXcelon, Inc. (formerly Object Design) by which universities can get
Object Store, eXcelon [a native XML store], and most other eXcelon
products for a total of $650/year. See our web site at This is a pretty good way to get into
OODB's if you are a university. The program applies in most of the

Bob Morris

Kevin Thiele writes:
 > Date:         Mon, 28 Feb 2000 09:47:10 +1100
 > From: Kevin Thiele <kevin.thiele at PI.CSIRO.AU>
 > To: TDWG-SDD at
 > Subject:      Progressive Revelation
 > At 15:30 24/02/00 +1100, Eric Zurcher wrote:
 > >6) I'm intrigued by the notion of a "Progressive Revelation model"
 > >(footnote 5). It sounds terribly theological - or perhaps that's
 > >Thiele-logical? (my apologies to Kevin, but I really can't resist bad puns).
 > I'm often accused of teleology, but rarely of theology.
 > Progressive Revelation is perhaps a new way of handling holes in data
 > matrices for random-access keys. The background is this:
 > The simplest data structure for a random-access key is a fully populated
 > matrix i.e. all taxa are scored for all characters/states. Works well
 > sometimes, especially if the taxa are highly comparable e.g. the species of
 > a genus or the genera of a family.
 > This structure is problematic sometimes though, for two reasons. Firstly and
 > most simply, you may not have data for all taxa, and need to leave holes in
 > the matrix. Solution is simple - fill the holes with ?s and allow for this
 > in the key program. But it often also happens that some characters are
 > simply inapplicable to some taxa, or (worse) are non-ambiguous for some taxa
 > but ambiguous for others. For instance, stipules don't occur in monocots,
 > stipule-like structures sometimes do but if you try scoring stipule
 > characters as defined for dicots against monocots you run into all sorts of
 > strife because of ambiguity of context. LucID can handle this to some extent
 > using the "present by misinterpretation" score, but the problem is in the
 > character definition, not the score.

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