Concrete Types Proposal
This is a proposal
for adding concrete data types
(essentially subtypes of rdfs:Literal)
to DAML-OIL.
It was developed by
Mike Dean
and presented to the
Joint Committee
on 19 December 2000.
Goals
- provide DAML ontology developers with "stronger typing" for data,
e.g. limiting property values to integer, float, date, etc.
- leverage the existing
XML Schema Datatypes Candidate Recommendation
- allow easy use of emerging XML Schema tools and libraries,
without requiring additional support in all DAML components
- allow DAML ontologies to use (at least) their own derivations of string,
e.g. Social Security Number
Specifics
- Allow use of an XML Schema Datatype URI as the
range of a property.
Such a URI may be either
- a reference to a builtin data type defined by the standard,
e.g. http://www.w3.org/2000/10/XMLSchema#string
- a reference to a user-defined derived type contained in an appropriate
XML document type, e.g. http://www.foo.com/2001/01/application#ssn
- Such URIs will implicitly be considered subclasses of rdfs:Literal.
- DAML components may make use of the range constraint
(and any other information derivable from it, e.g. by
retrieving the referenced XML Schema definition),
or may behave as if rdfs:Literal were specified instead
(i.e. just treat the value as a string).
Example
Application-specific XML Schema types defined in
example.xsd.
Simple ontology using these types defined in
example-ont.daml.
Issues
- This approach (explicitly) doesn't support reasoning about types
at the DAML language level.
- What is now the range of range?
Should it still include rdfs:Literal?
Was rdfs:Literal ever really a Class?
(Making types implicit subclasses of rdfs:Literal means that the
range of range doesn't have to change.)
- Can we replace DAML lists with XML Schema lists?
That should provide stronger typing of the list elements (itemType).
$Id: 2000-12-19-mdean-concrete-types.html,v 1.5 2000/12/19 07:21:34 mdean Exp $