Yes, I agree with what John says. (01)
SBVR (the OMG "Semantics of Business Vocabulary and Rules" standard) comes
at semantics, ontologies, and rules from the perspective of business users
and business usage. It is defined using "SBVR Structured English", which is
a form of Controlled Natural Language. An important (but under-defined from
a logician's point-of-view) concept in SBVR is "state of affairs", which is
the class of instances of propositions. So one can define "employment" as
the state of affairs that a company employs a person, and then one can
define attributes of the "employment" concept -- i.e. attributes of the
class of instances of any proposition that uses "company employs person". (02)
When Ed, I, and others defined a "Date-Time Vocabulary" for SBVR, one of the
key requirements was to relate time to concepts such as "employment". We
used "state of affairs" for that. We also mapped the key aspects of the
Date-Time Vocabulary to Common Logic and IKL, using the "that" operator to
express the relationship between propositions such as "company x employs
person y" and attributes such as start date. (03)
Net: the IKL "that" operator is key to addressing a requirement that arises
in modeling real business vocabularies and rules. (04)
Mark (05)
-----Original Message-----
From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx
[mailto:ontolog-forum-bounces@xxxxxxxxxxxxxxxx] On Behalf Of John F Sowa
Sent: Friday, June 13, 2014 4:10 PM
To: ontolog-forum@xxxxxxxxxxxxxxxx
Subject: Re: [ontolog-forum] Requesting Opinions on the Benefits of
Predicates as Nodes (06)
Jack and Mark, (07)
I've been backing up through this rather lengthy thread, and I finally got
to your two comments near the beginning: (08)
JP
> If I might add, I will assert that predicates as first class citizens
> is perhaps the only difference between an RDF graph and a topic map. (09)
MHL
> Consider the triple {CompanyX employs Person1} using a predicate
> called "employs". The triple implicitly describes what an English
> speaker would conceptualize as an "employment", with attributes such
> as "start date", "end date", a location, etc. (010)
Yes. This is an important issue, and it's obscured by an unfortunate
tendency of some logicians to call verbs predicates. (011)
Peirce observed that when you say "Mary gave a child a book" there are four
entities involved: Mary, the child, the book, and the act of giving. He
allowed any or all of the four entities to have its own existential
quantifier (or "line of identity"). (012)
About 70 years later, Donald Davidson rediscovered the advantages of
assigning quantified variables to verbs -- for the same reasons that Jack
and Mark cite. (013)
For conceptual graphs, anything you might want to refer to or link to is
represented by a concept node. Anything you don't intend to refer to is
represented by a relation node. But you always have an option of analyzing
any relation as a graph with more nodes that can be referred to or linked
to. (014)
For the KR ontology (http://www.jfsowa.com/ontology/ ), the default mapping
is to assign a concept node to every verb. That node has an implicit
quantifier, which represents the action or the state. (015)
The idea of using the letters SVO to refer to the three parts of an RDF
triple is more confusing than helpful. I don't recommend it. (016)
John (017)
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