At the risk of embarrassing myself (since I certainly am no expert on CL or IKL), I’ll try to show what we want to do by example:
Starting from the simplest example: in SBVR, one could define what’s called a verb concept, such as “company employs person”, where ‘company’ and ‘person’ are roles that range over concepts of the same name. One might have a rule such as ‘if some company employs some person, then ….” which in CL would be:
(exists (company c)
(exists (person p)
(if (employs c p)
… )))
Building up the example, suppose the conditional part of the rule instead is “if some company employs some person during July, then ….” Using the IKL “that” operator and a “during” relationship and the concept “July” (a ‘calendar month’):
(exists (company c)
(exists (person p)
(exists (‘calendar month’ July)
(if (during (that (employs c p)) July)
… ))))
Building the example some more, imagine the concept ‘employment’, whose extension contains instances of a company employing a person:
(forall (c p)
(iff (employment c p)
(and
(company c) (person p)
(that (employs c p) ))))
Now the final step, a rule about the date of an employment (an example of what I meant by “an attribute of a class”): “if there is some employment during July, then ….”:
(forall (employment e)
(exists (‘calendar month’ July)
(if (during e July)
…) ))
I’m not at all sure that I’ve got this right, but I hope it shows what we want to do.
The Date-Time Vocabulary is at http://www.omg.org/spec/DTV/. Clause 16 defines how we relate situations to time, and clause 16.7 (“Propositions, Situation Kinds, and Occurrences”) describes how we attempt to make sense of the SBVR “state of affairs” concept.
Mark H. Linehan
-----Original Message-----
From: Pat Hayes [mailto:phayes@xxxxxxx]
Sent: Sunday, June 15, 2014 11:09 PM
To: Mark H Linehan
Cc: [ontolog-forum]
Subject: Re: [ontolog-forum] Requesting Opinions on the Benefits of Predicates as Nodes
On Jun 13, 2014, at 8:18 PM, Mark H Linehan <mhl@xxxxxxxxxxx> wrote:
> Yes, I agree with what John says.
>
> 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.
Oh dear.
> 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.
That does not appear to make sense, as stated.
In my understanding of "proposition", propositions are not the kind of thing that can have instances. Can you expand on what you mean by 'instance of a proposition'? How does this idea relate to the similarly named 'instance of a class'?
> So one can define "employment" as
> the state of affairs that a company employs a person,
Let me use CLIF notation here for a second. Do you mean
(employs C P) for a particular C and P
or
(exists (C P)(employs C P))
or
(lambda (C P)(employs C P)), ie simply the relation employs
or
(that (employs C P)) ie the proposition that C employs P, for a particular C and P
or
(that (exists (C P)(employs C P))) ie the propositionthat something employs someone
or maybe
(lambda (C P)(that (employs C P))) ie the function from two things to the proposition that the first employs the second
or...
Alternatively, can you give some kind of precise account (preferably stated using mathematical ideas) of what kind of structure counts as a proposition, an instance of a proposition, etc..
> and then one can
> define attributes of the "employment" concept -- i.e. attributes of
> the class of instances of any proposition
Attributes of the CLASS? Really? (Classes don't have many attributes, as a rule.) Or do you mean attributes of the instances of the class? (But then - see above - what *are* the instances of this class??)
> that uses "company employs person".
>
> 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.
Really? As nothing you have said so far even mentions temporal ideas, I wouild love to know more about how you did that. Pointer?
Pat Hayes
> 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.
>
> Net: the IKL "that" operator is key to addressing a requirement that
> arises in modeling real business vocabularies and rules.
>
> Mark
>
> -----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
>
> Jack and Mark,
>
> I've been backing up through this rather lengthy thread, and I finally
> got to your two comments near the beginning:
>
> 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.
>
> 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.
>
> Yes. This is an important issue, and it's obscured by an unfortunate
> tendency of some logicians to call verbs predicates.
>
> 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").
>
> About 70 years later, Donald Davidson rediscovered the advantages of
> assigning quantified variables to verbs -- for the same reasons that
> Jack and Mark cite.
>
> 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.
>
> 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.
>
> 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.
>
> John
>
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