RE: Type coercing a resource's type?

I guess from the following construct (present somewhere), it could be
inferred that "EastChinaSea" is an instance of rdf:Type Sea.

<Sea rdf:ID="EastChinaSea"


-----Original Message-----
From: Roger L. Costello [] 
Sent: Saturday, February 22, 2003 3:06 PM
Subject: Type coercing a resource's type?

Hi Folks,

Consider this class hierarchy:

               |  |  |
        --------  |  --------
        |         |         |
        |         |         |
       Lake     Ocean      Sea

In my RDF Schema I have defined a property EmptiesInto to have a
rdfs:range value of BodyOfWater:

    <rdf:Property rdf:ID="EmptiesInto">
        <rdfs:range rdf:resource="#BodyOfWater"/>
        <rdfs:domain rdf:resource="#River"/>

Thus, when used in an RDF/XML instance the value for EmptiesInto can be
a Lake, Ocean, or Sea.

Here's a sample RDF/XML instance which shows that the Yangtze River
EmptiesInto the EastChinaSea:

    <?xml version="1.0"?>
    <River rdf:ID="Yangtze"
       <Length>6300 kilometers</Length>

From the RDF Schema I can infer that

is a BodyOfWater.

However, I "should" be able to know more specifically that it is a Sea.

If this was a programming language I would do a type coercion to coerce
it to Sea.

My question is this: is there something that I can do in the RDF Schema
to indicate:

    "For the Yangtze River instance the property 
     EmptiesInto has the more specific type Sea"

That is, in an RDF Schema can I make statements about particular
instances?  /Roger

Received on Saturday, 22 February 2003 17:25:56 UTC