Thank you for the response. I plan to do much reading and little writing on this topic, which I obviously know little about.  So, don't expect any futher e-mails form me in the foreseeable future.

However, I deeply appreciate your attempts to help me. Perhaps you want to indicate to Dr. Ogbuji that the example that you used in your response is likely to be more clear to us old-timers trying to learn new tricks.  On another note, your comments on my prior e-mail  show that I lack education in post-Aristotelian logic. I concur; my only college course even close to the field of modern mathematical logic was Introduction to Modern Algebra, textbook by Neal H. McCoy, edition of 1968, which I took in about 1970. Subsequently, I have read extensively in a few books that were oriented to writing better computer programs in Fortran in the 1970's and which discussed logic a bit. Since then I have only dabbled in logic on the level of: All Greeks are liars AND Socrates is a Greek; therefore, Socrates is a liar.   (A poor example, but one which came to me quickly.)  Recently, however, my adult son an! d I have begun working on some projects using XML, etc.  so I'm reading a lot of relevant books and articles on this topic, but Dr. Ogbuji's example in that article threw me completely off.

Thanks again,

Ivon Fergus

>From: patrick hayes
>To: "Ivon Fergus"
>CC: www-rdf-comments@w3.org
>Subject: Re: I'm Confused About RDF: A Subject is Not A Predicate, etc.
>Date: Mon, 13 May 2002 01:02:55 -0500
>
>>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.
>
>Unfortunately there is no 'common meaning' for these terms. What
>meaning they have depend on ones technical background and the
>assumptions made by the particular field one works in. Certainly,
>however, one should not think of RDF in terms developed for
>linguistic analysis of natural language.
>
>> For example, the word "author" is the subject of the sentence,
>>not
>>the predicate.
>
>You may have found Ogbuji's example less confusing if it had been
>phrased thus: "The Lord of the Rings [subject] has as
>author[predicate] J.R.R. Tolkien [object]" , retaining the triple
>ordering in the English syntax. However, I presume his rendering was
>intended to convey the intended meaning rather than the grammatical
>structure. The RDF terms refer to the 'subject', 'predicate' and
>'object' of the RDF triple, not of the explanatory sentence. (The
>exact terminology is not in fact terribly important: they could be
>called 'middle/first/last' and the content of the RDF would not be
>altered in the slightest degree. The terms chosen were intended to
>be
>intuitively helpful, in that an RDF triple is often thought of
>intuitively as being 'about' its subject, but if you find the
>intended (weak) analogy unhelpful, then it would be best to ignore
>it
>altogether.)
>
>>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 statement:
>>
>>"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.
>
>The topic of your schooldays was apparently English grammatical
>analysis of a certain traditional kind (used in 'prescriptive'
>rather
>than 'scientific' linguistics.) RDF is not English, however. It is
>closer to the kinds of information found in relational databases
>than
>it is to natural language.
>
>It might be better to think of an RDF triplet as asserting that a
>relationship holds between two entities. The above example then
>asserts that a relationship called "author" (or possibly
>"author_of"
>) holds between the entity called "The Lord of the Rings" and the
>entity called "J.R.R.Tolkein", in that order. This could be
>expressed
>in English in a number of grammatically distinct ways; the
>'predicate/subject/object' terminology is not meant to refer to the
>grammatical structure of those English sentences, however.
>
>>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.
>
>Speaking now as a logician, I would argue with the coherence of this
>characterization. This way of talking seems to me to be rooted in a
>rather primitive (Aristotelian) view of logical structure, which was
>superceded by mathematical logic in the late 19th/early 20th
>century.
>Why is it correct to say that when I buy a book , that the book has
>'transitioned' but I have not? An ownership property of the book has
>indeed changed, but it is also correct to say that an ownership
>property of me has changed: I now own a book that I did not own
>before. It is more accurate to say that an event of buying is a
>change in a *relationship* between two things (me and the book). The
>subject/object distinction is in fact a linguistically arbitrary
>aspect of English grammar, and has no logically coherent
>justification. The same event can be described in the English
>passive
>with the book as the grammatical subject: "The book was bought by
>me."
>
>>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.
>
>There are (at least) as many English grammars are there are theories
>of linguistic structure. None of them are universally accepted or
>definitive, however, so it seems to me to be meaningless to refer to
>"English grammar" in the singular.
>
>>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.
>
>The basic mistake is to try to read the RDF as though it were
>natural
>language. Ogbuji was trying to be helpful, but I think you read far
>too much into his example.
>
>>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.
>
>I am not sure where on when you went to school, but these ideas
>certainly pre-date my own school years. The basic 'massive shift'
>took place in the work on relations by Peano, Frege and others
>towards the end of the 19th century, and was made permanent in the
>English-speaking world by "Principia Mathematica" by Russell and
>Whitehead , published in 1910. Almost all of logical semantics has
>been based on these ideas since the work of Tarski in the 1940s, and
>modern linguistic theories have been predicated on similar
>underlying
>semantic and grammatical structures since the work of Chomsky in the
>1960s, and possibly earlier.
>
>>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.
>
>In a nutshell: think of the RDF as a graph. The nodes of the graph
>name entities, and the arcs of the graph refer to relationships. The
>RDF graph asserts that relationships hold among the entities in the
>pattern defined by the graph. (Other relationships may also hold
>among them; the RDF graph does not deny that possibility.) A
>'blank' node in a graph asserts that an entity exists without
>actually naming it, as for example when one might wish to say that
>someone has a son, without knowing the son's name.
>
>Exactly what counts as an entity is left open, so that RDF can
>describe relationships among arbitrary entities; similarly, exactly
>what counts as a relationship is left open; all that RDF requires of
>a relationship is that it hold or not hold between entities; in
>other
>words, that RDF triples are either true or false.
>
>I hope this has been of some help.
>
>Pat Hayes


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