Graham --

You wrote...

Does anyone have any examples of using OWL to perform RDF-datatype-related inferencing?
I'm thinking of datatypes, such as numbers, for which additional properties are used to define additional relations, such as addition over numbers.
For example, given:
:vehicle :seatedCapacity "30"^^xsd:integer .
:vehicle :standingCapacity "10"^^xsd:integer .
and knowledge that the total capacity is seated capacity + standing capacity, that one might infer:
:vehicle :totalCapacity "40"^^xsd:integer .
This might be expressed thus using CWM-style rules:
{ ?v :seatedCapacity ?c1 .
?v :standingCapacity ?c2 .
(?c1 ?c2) math:sum ?c3 . }
{ ?v :totalCapacity ?c3 . }
It seems to me that to express such relations one must have a form of universal quantification. But I'm not sure if anything in OWL performs such a purpose, so I struggle to see how one might express an idea like that above.

Here's how you would do this in our inference system, keeping to triples notation.  The quantification is implicit.

Table of facts:

this-vehicle has this-capacity of type this-type
  bus             30                    seated
  bus             10                    standing


some-vehicle has some-capacity1 of type seated
that-vehicle has some-capacity2 of type standing
that-capacity1 + that-capacity2 = some-capacity
that-vehicle has that-capacity of type total

You can run (and modify) this example by pointing Netscape 7 or Mozilla to

Click on Internet Business Logic, then on GO. 

Select "SeatingCapacity". 

Then, please use the Help button to navigate through the pages on which you run the rule, get the answer 40, get an explanation, modify the facts and rules, and so-on.  One could also add type-checking to the above rule, using the same notation.

There are also some fairly sophisticated e-commerce  rule sets.

To try to address the more general question that you outline, the definition of addition is "predefined" in the system, along with the usual arithmetic and other suspects.

Hope this helps.                    Cheers,  -- Adrian

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