Dear Martijn, All,
As you state, an empty collection does not really work, because nothing
is curated or created. This would be "Relational Database" thinking,
where you fill in slots.
The interesting thing is, to be clear about WHAT is negated. What is a
"no archaeological finds at all" ?
Obviously, it needs a specification of WHAT was sought or expected
starting the investigation. This appears to be E55 Types. So, we have a
property "O19 <#_O19_has_found>* has found object of type (was type of
object found by)", and its negative. This is not dramatic, to define for
all respective properties the "categorical" equivalent, and the
negative, once they are simple deductions, and do not proliferate.
But interesting is also the activity of seeking, but not finding. So, a
survey is seeking, results in n encounters. Here, we have "no encounter
event", no event linking to "object of type". This is more complex. The
"no" is about the event....
Comments?
martin
On 11/5/2019 5:36 PM, van Leusen, P.M. wrote:
Dear Athanasios,
this same issue came up during discussion of the ontology of
archaeological field surveying, where we wish to (and in some cases,
have in fact) recorded the absence of surface finds from a specific
piece of investigated land. A typical situation would be, that a
survey team has 'walked' a field with a particular observation
intensity, say 20% (so 20% of the field's surface has actually been
inspected), and has made no archaeological finds at all. This results
in an 'empty' collection (0 finds), which is a valid outcome just like
1, 10 or a 1000 finds would be. It was suggested by George Bruseker to
model such survey collections as Curated Holdings, but that only works
as long as there is something physical to curate - so it does not work
for 'empty' collections.
So, what solutions might be possible, analogous to the options that
you've presented here? Either we allow Curated Holdings with zero
members, or we introduce negative properties.....
Martijn
On Tue, Nov 5, 2019 at 4:03 PM Athanasios Velios
<[email protected] <mailto:[email protected]>> wrote:
Dear all,
Following the Linked Conservation Data workshop and the last SIG in
Crete I am summarising the problem of documenting non-existence.
An example of non-existence is: a book cover (a particular) without
tooled decoration (a type).
Options for encoding:
1) As discussed here:
http://lists.ics.forth.gr/pipermail/crm-sig/2012-November/001873.html
,
we could have a new E55 Type "books without decoration". This is a
good
solution but the problem is that we will need an unmanageable
number of
composite thesaurus terms to cover all possibilities, e.g. things
without a feature, or types of events which did not happen etc.
2) In past SIGs we have mentioned negative properties. This is also a
good solution but not quite in scope. A negative property requires
particulars for domain and range. So I can say that:
cover(E22 Man-Made Object) → NOT P56 bears feature → tooled
decoration(E25 Man-Made Feature)
This would mean that the specific book does not carry the specific
decoration. But I want to say that the specific book does not
carry any
decoration.
3) So I pestered Carlo for a few days and he says:
"To express negative information in an ontology, it is recommended to
use specific axioms. For example, to state that certain books have no
decorations the axiom would require to create a special class for
those
books and to make that class a sub-class of the class expression
'individuals with less than 1 decorations'. This will require a class
and an axiom to be created for each type of negative information
to be
expressed. But it has the advantage of using a standard OWL 2 DL
inference engine to reason about that negative knowledge, both for
maintaining consistency and for query answering."
So what Carlo thinks is that option 1 is reasonable and in fact
instead
of using simply a thesaurus, one should elevate these definitions to
ontology classes and axioms.
I would be interested to hear views from the list, as I am not
sure how
to model such statements. Those of you who have looked at this in the
past, do you get a sense of the scale for negation statements?
Thank you.
Thanasis
P.S. A parallel thought which did not capture Carlo's imagination
was a
"typed negative property", i.e. create new negative properties
with E55
as range as in:
cover(E22 Man-Made Object) → NOT P56 bears feature of type → tooled
decoration(E55 Type)
but I am not sure how this would translate to logic in an
inference engine.
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Dr. Martijn van Leusen
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Archaeology
Poststraat 6, 9712ER Groningen (Netherlands) / phone +31 50 3636717
Chair, Examination Board for Arts, Culture and Archaeology / Chair,
Faculty of Arts Advisory Board for Data Management policies
Academia page <https://rug.academia.edu/MartijnvanLeusen>
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