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Re: Syntax vs Semantics vs XML Schema vs RDF Schema vs QNames vs URIs (was RE: Using urn:publicid: for namespaces)

From: Thomas B. Passin <tpassin@home.com>
Date: Sat, 18 Aug 2001 02:04:43 -0400
Message-ID: <00f701c127ab$ad798e00$7cac1218@reston1.va.home.com>
To: <www-rdf-logic@w3.org>
I included a table in my last post, but it seems to have gotten wordwrapped,
so I will repeat it with shorter generated ids.

> Now if John did indeed have two fathers after all, the situation would be
> more complex, because on merging the two data sources, our processor would
> have to convert the hasFather statements into some kind of a container,
> which itself would apparently be an anonymous node.  It would be something
> like this (with apologies for the undefined terms):
 subject              property          object
 John                  hasFathers      []
 []                      typeOf            container
 []                      RDF_1             randomgenid0
 randomgenid0   typeOf            malePerson
 []                     RDF_2             randomgenid1
 randomgenid1   typeOf            malePerson
 randomgenid0   age                 84
 randomgenid1   age                 86

Without the labels randomgenid0, randomgenid1 it would be
much harder to make this set of assertions, if it were possible at all.
Certainly we couldn't enter this data into a relational database, or write
it down on paper in a table like this, since we would have to use three
different "[]" symbols that looked the same but refered to three different
resources.  To be consistent, of course, I should have used a generated id
instead of [] for the container as well.

> Indeed, if you think of a set of triples as being rows in a relational
> database table, then ask what would be the primary key of that table?  The
> only sensible answer is that the primary key must be the combination of
> subject and predicate.  The "semantics" could also be considered to be a
> kind of "business rule", to use an expression from a different domain.
> Taking this relational database viewpoint, each node must necessarily have
> value (or label), but it may be that a particular implementation could
> the label, or exclude it from serialization.


Tom P
Received on Saturday, 18 August 2001 02:01:46 UTC

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