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Re: [ontolog-forum] is-part-of: a really, really, bad practice?

To: "Ontolog (E-mail)" <ontolog-forum@xxxxxxxxxxxxxxxx>
From: "John McClure" <jmcclure@xxxxxxxxxxxxxx>
Date: Tue, 28 May 2013 15:06:54 -0800
Message-id: <002c01ce5bf8$0bc526d0$0200a8c0@McClure>
comments below
-----Original Message-----
From: William Frank
Sent: Monday, May 27, 2013 7:33 PM
To: [ontolog-forum]
Subject: Re: [ontolog-forum] is-part-of: a really, really, bad practice?

On Mon, May 20, 2013 at 7:58 PM, David C. Hay <dch@xxxxxxxxxxxxxxxxxxxxxxx> wrote:

This is one of my major beefs with both the data modeling and the ontology worlds.  Harry Ellis and Richard Barker, back in the 1980s, have come up with the perfect way to name relationships.

For specifying information models in a normal person friendly way, I agree completely.  But not mathematically.
[JMc] I am building an ontology for semantic wikis - to be used by normal friendly people. I do care about the quality of the ontology mathematically, which is exactly why I initiated this discussion.
Since the point of an ontology is to describe what is, "is" is the only verb that should be the basis for a relationship.  Indeed, in the data modeling world, optionality is important, so the verb actually turns out to be "must be" or "may be". 

This is a facile argument.  I and most other who have learned  logic, would make the 'must' or the 'may'  *not" part of the sentence, but an assertion *about* the sentence. 
[JMc] I agree that that time/deontics form an assertion about the existence/state of the asserted concept.

For example MUST (Alcohol an organic compound) MAY (Alcohol is poisonous).
[JMc] yes 

You are searching for the part of speech to use. 

Not me. I am not looking for ways to express entities and relationships to subject matter experts. If I were doing this job, I would be doing it the way you say.
[JMc] For whom are you wishing to express your entities & relations? It's nice to hear you're not dismissive of using prepositional predicates. 
No, nouns don't work, since nouns are already the subject and object of the sentence. 

Again, facile, who can' nouns be all three parts.  An equivelent argument,  How should subjects be represented?  Not by nouns, because nouns are already the object of the sentence!
[JMc] It makes no sense that a triple is composed of three nouns. The predicate is the arc's label, it is NOT a concept which, to me, is the root of the problem here. In practice I see here on Ontolog, the predicate is constantly spoken of as a "concept" itself. Predicates cannot be conceptual in nature. But by associating "formalisms" with a predicate then you are treating a predicate as a concept that has attributes, namely, those darn formalisms are attributes of predicates like "isPartOf". At the same time I am NOT saying that formalisms are bad, I am saying that formalisms exist apart, indexed by predicate/subject type/object type, to be looked-up.

John Fatherhood Sally.

I bet you can understand this.   But, it is directional, not fully analytic.

Exists Fatherhood where John Father, Sally Child in Fatherhood

[JMc] The Fatherhood instance relates only to John's relationship to Sally. Sally has a separate Daughterhood instance. None of these instances are 'shared' among the parties to the relationship -- each participant has its own relationship instance(s).
We are trying to see how the nouns are related to each other. Verbs don't work, since we are not trying to model processes, here.  Just existence.  Let's see, what part of speech can we use for relationships?

Grover in Sesame Street actually has it right.  Prepositions!  This is the part of speech that is about relationships: over, under, around, and so forth.  Think "Grover words".
[JMc] thank you Dave - this is where the name "Grover Model" comes from 

In Harry's and Richard's world, relationships can be expressed in strong assertions, in the form:

Each [subject] must be|may be [predicate] one and only one|one or more [object]. 

For example, each PERSON must be son of one and only one MALE PERSON, and each MALE PERSON may be the father of one or more PERSONS.

This is great for expressing this in a clear way with clients, but it is not as deeply simple as

the motherhood  relation has two role, the child role and the mother role. 

the child role is played by an animal that the mother in the relation gave birth to.

the mother role is played by an animal that gave birth to the child.

As someone else said recently, events usually determine relationships.

the fact that mother role in the motherhood relation is constrained to female animals is a logical consequence of the above and other assertions, better than stating that derived constraint in the relation definition.
The Romans were the destroyers of Carthage;  Carthage was destroyed by the Romans. (Since this describes the past, we can dispense with "must be" and "may be".  "Was/were" works just fine.)
[JMc] then so you have a triple something like <Army:Roman Army> is-a <Type:Destroyer> ? Where's the role stated, in triples? maybe <City:Carthage> has <Destroyer:Army:Roman Army>? Your narrative is only the first step; the next is to model the stated facts in triples.

And so forth. 

I've been using this structure for some 25 years, now, with remarkable success in carrying out meaningful conversations with subject matter experts in many fields. 

I agree that what you have been doing is the very best way to do this. 
[JMc] hard for me to evaluate yourpractices since I'm talking triples (where the rubber hits the RDF road) and you're (both) talking somehwat narratively. 
I was amused to see the Semantic Web pick up the idea with RDF a few years ago, although none of that group figured out that adding discipline to the way predicates were formed could add incredibly to the power of the ontologies created.
[JMc] what discipline(s), are you saying? 

Remember, these are ontologies being created.  They are supposed to describe what exists, not how it came about.
[JMc] I was planning on a Timeline for each resource, along which are plotted events.
Now that you said it, I wonder if separating action and fact misses an opportunity.  There is a duality  between the two.  You ARE married because you GOT married, and nothing making that false happened in between.   you cannot get divorced unless you ARE married[JMc]  or, unless you HAVE a Spouse or you ARE a Spouse.  Why in the world is it good to create a set of rules about static relationships *separately* from their duals in the world of action?   Why not do both together? [JMc] Substantially they are done together, because the fact of a particular role (its provenance if you will) should reflect the marital event and or a certificate about the event.    To me, this might be the most lasting lesson of object-orientation.  OTOH, most behavioral rules, and even the set of states a thing can have, change more rapidly.   For instace, I use UML mostly because I want to create state transition models, and these have to be unifies  with the classes.   But, I do the static e/r type models first. 


Dave Hay
Houston, Texas

(I love it that "ontology" has become a 2500-year old hot new buzzword . . .)

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