Re: [xdi] owl:inverseOf, owl:ObjectProperty, owl:DatatypeProperty

Bill, I want to address your second point below -- that "the examples in the XDI Graph Patterns document the property +age and +age! is used interchangeably" -- but I don't have time tonight, having just used up all extra time with the last message about $same.

But I just wanted to point out that in the XDI Graph Patterns document the property +age and +age! is NOT used interchangeably. Unless there is a mistake in the document (and there could be), +age! is ONLY used as a literal arc and +age is ONLY used as a contextual arc. And that's exactly the way it should be, because +age would be defined in an XDI dictionary as being a literal (+age/$is$a/!), so to instantiate it as a literal arc would require identifying it as +age!.

When it is used as a contextual arc, i.e., an arc identified ONLY as +age, then it by definition does NOT stand for the literal, but for the identity of the +age property (and therefore the place to "hang" metadata about that property, such as a datestamp).

Hope this helps,

=Drummond (going to bed now!)

On Tue, Jul 5, 2011 at 10:17 AM, Barnhill, William [USA] <> wrote:

Thanks Giovanni. owl:inverseOf was my inspiration for $inv. Where possible we seem to be following a convention of 2-3 letter dollar words.

The distinction between ObjectProperty and DatatypeProperty is a thorn in semantic software engineers sides, and why I was against the bang usage and for a literal to be denoted by an XRef with a data: scheme, which works well, does not require extra syntax, and does not require the semantic disconnect of having two types of properties. The tradeoff costs are that the data URI needs to be parsed and that it requires a few more bytes per literal. Also in the examples in the XDI Graph Patterns document the property +age and +age! is used interchangeably, which I don't believe it can be.

Bill

________________________________________

From: Giovanni Bartolomeo []

Sent: Monday, July 04, 2011 6:20 AM

To: OASIS - XDI TC

Subject: [xdi] owl:inverseOf, owl:ObjectProperty, owl:DatatypeProperty

This might be useful to define the semantics of our $word

http://www.w3.org/TR/owl-ref/#inverseOf-def

in particular, one could assume that, in XDI, $inv<someproperty> is a

shortcut for this:

<owl:ObjectProperty rdf:about="$inv<someproperty>">

   <owl:inverseOf rdf:resource="<someproperty>"/>

</owl:ObjectProperty>

Likewise in OWL one can distinguish between owl:ObjectProperty and

owl:DatatypeProperty, which is roughly the same as not having or

having ! at the end of an XDI predicate, i.e. the range of the

predicate is an object or a datatype:

<owl:ObjectProperty rdf:ID="+age"/>

<owl:DatatypeProperty rdf:ID="+age!"/>

So XDI should be more OWL (DL) oriented than "pure" RDF oriented...

Giovanni

> 4) MOVING FROM METAGRAPH SYMBOLS TO METAGRAPH WORDS

>

> See Drummond's email to the list and subsequent discussion:

>

>   http://lists.oasis-open.org/archives/xdi/201106/msg00029.html

>

> Drummond summarized last week's discussion, and said that is really

> becomes an aesthetic decision by the TC, since $ ==>$is, * ==> $has,

> and ! ==> $a are functionality identical.

>

> Bill said that he is in favor of moving back to metagraph words for

> these symbols, but feels we should have separate $words for

> equivalence and inversion.

>

> Giovanni pointed out that even though RDF does not have an

> algorithmic way to express inversion, Linked Data does suggest that

> nodes that are linked also include the inverse link so that you can

> discover the relationship in both directions.

>

> Note that by itself, adopting a separate $word for inversion is not

> a solution to the RDF incompability issue.

>

> # ALL - Send your stack-ranked choice for a new $word for asserting

> inversion as an email to the list before next week's call.

>

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