chung wrote:
> When my RDF parser detects an empty string or a value that should be
> numeric but cannot be cast as such, it overrides it and considers of it
> to be missing. I'll try to fix that - I just need one more check in a
> critical step of the RDF parsing, so I think it wont be very difficult.
> The message "Can't Handle class attribute" (because the class attribute
> is of type String) appears because there is some non-numeric entry for
> the specified target feature which characterizes the whole feature as
> String. Many issues will be fixed if we establish datatype declarations
> for features.
>
>   
Actually,  I could not find a way to define "data type declaration for
objects" in OWL (Protege 3.4) , which is understandable, provided that
all the domain/range restrictions on properties are not really 
restrictions ,as in the object oriented mindset, but are used by
reasoners to infer new facts.

Some preliminary ideas how to define restrictions on properties and
subsequently define a dataset, restricted to only numeric values is in
the attached opentox.owl  (under development, not yet uploaded on the
web site).   It seems better fitted to OWL is to declare  datatypes of
values and then use queries to find out which features have particular
type of values.

Nominal values are another interesting issue, which could be modeled in
OWL either as enumeration datatypes, or as individuals, not as literals,
and further by owl:allVauesFrom property restrictions.  This is also
quite reasonable, since it is hard to automatically tell if a feature is
a string or nominal value, without some human intelligence. 

Some background gathered from several sources at
http://opentox.org/data/documents/development/RDF%20files/Datatypes/ ,
for those who seek something to read on the New Year eve ;)

Advice from ontology experts on best practices is very much appreciated!


Best regards,
Nina
> Best Regards,
> Pantelis
>
>   

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