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Re: I'm Confused About RDF: A Subject is Not A Predicate, etc.

From: Uche Ogbuji <uche.ogbuji@fourthought.com>
Date: 10 May 2002 20:37:49 -0600
To: Ivon Fergus <ivonfergus@hotmail.com>
Cc: bob@newarchitectmag.com, danbri@w3.org, guha@guha.com, phayes@ai.uwf.edu, www-rdf-comments@w3.org, Amit Asaravala <amit@asaravala.com>, Neil McAllister <NMcAllister@cmp.com>
Message-Id: <1021084673.14471.1620.camel@borgia.local>
BTW, you have an interesting collection in your To: field.

I'm sorry if my article contributed to your confusion.  I actually tried
to pick an example that illustrated that you need not get too tied up in
linguistinc grammar rules when preparing RDF models.

If I understand you correctly, you seem to think that when I say

"RDF statements are hardly as complex as those we use in natural
language. They have a uniform structure of three parts: predicate,
subject, and object. For example,: the author [predicate] of The Lord of
the Rings [subject] is J.R.R. Tolkien [object]."  

That the descriptions in square brackers refer to the english parts of
speech.  I tried to make it clear that they refer to the components of
the RDF statement, not the English parts of speech.  Yes, in this case
the subject of the English sentence becomes the predicate of the RDF
statement.  This is indeed the key point.

Quoting from English grammars is rather off the mark as we're not
discussing English grammer, eh?

Right after the passage you quote, I try to make things even clearer by
illustrating the parallel to Object Oriented design conventions.

Again, I'm sorry my example confused you.  I'm a bit comforted that I've
received over 7 comments on the article, though it's only been up for
one day, and mop one else seemed to have the same misunderstanding.

Thanks for your comments.


On Fri, 2002-05-10 at 20:09, Ivon Fergus wrote:

First, I need to do a lot more research before I get into the subject of
RDF at any length. However, because the magazine New Architect (formerly
Web Techniques) has published an article in its June 2002 edition by Dr.
Uche Ogbuji entitled "The Languages of The Semantic Web", I feel that it
is vital to get the ball rolling now, even though I'm not at all sure in
which direction. Specifically, on p. 31, Dr. Ogbuchi makes the following
amazing statement:

"RDF statements are hardly as complex as those we use in natural
language. They have a uniform structure of three parts: predicate,
subject, and object. For example,: the author [predicate] of The Lord of
the Rings [subject] is J.R.R. Tolkien [object]."  

I will make some assumptions; Please correct me if I am wrong.  My first
assumption is that there must be a valid reason to totally diverge from
the common meanings of these terms.  For example, the word "author" is
the subject of the sentence, not the predicate. The booktitle is the
object of the preposition "of", not the subject, and only in some
respects can "J.R.R. Tolkien" be considered an object.When I went to
school, the noun or pronoun following an intransitive verb, such as "is"
was called a predicate nominative, not an object. For example on web
page: http://englishplus.com/grammar/00000016.htm is the following

"Predicate Nominative 

A predicate nominative is a noun or pronoun which follows the verb and
describes or renames the subject. It is another way of naming the
subject. It follows a linking verb. The predicate nominatives on this
page have been italicized."  

I assume that "linking verb" is a synonym for intransitive verb.Perhaps
a few things have changed a bit since I was in school, but the only time
we referred to a noun or pronoun as an object was when it followed a
transitive verb and was its object. For example in the sentence, "He
bought a book." the noun "book" is the object because it has
transitioned in some way.  In this case, certainly not physically, but
in terms of ownership. In the sentence, "He burned a book." it is more
obvious that the book is the object, and English grammar also defines
indirect objects as well as direct objects, so I can understand that
reasonable people can disagree about exactly what is a certain part of
speech and quibble in the finer parts of English grammar. Nevertheless,
Dr. Ogbuchi's rendition of RDF grammar in this passage is so disjoint
from "natural language" as to be incomprehensible by an educated
person. I am at a complete loss as to why these definitions depart so
radically from what I learned in school. I decided that there must be
very important consideraitons that I am oblivious to that necessitated
this massive shift, or perhaps Dr. Ogbuci or New Architect needs to
issue a clarification to this article.

Having deduced that much, I went to some of the relevant draft documents
on the W3 website, seeking enlightenment. I briefly reviewed
http://www.w3.org/RDF/ , http://www.w3.org/TR/rdf-mt/ , and
http://www.w3.org/TR/rdf-mt/, and now must confess that I am even more
profoundly confused than before. Now, I am not an ignoramous, so I beg
for the RDF primer that one of these documents alluded to, so that I can
begin to understand these documents and thus RDF grammar, syntax, and
effective usage.  Perhaps I should have looked at other web pages. Would
at least one of you be so kind as to respond?

Thank you,

Ivon Fergus




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Uche Ogbuji                                    Fourthought, Inc.
http://uche.ogbuji.net    http://4Suite.org    http://fourthought.com
Track chair, XML/Web Services One (San Jose, Boston):
DAML Reference - http://www.xml.com/pub/a/2002/05/01/damlref.html
The Languages of the Semantic Web -
XML, The Model Driven Architecture, and RDF @ XML Europe -
Received on Friday, 10 May 2002 22:40:19 UTC

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