John, (01)
You wrote: (02)
> Example: if "isFatherOf" is said to be a valid relation between A & B, how
>can know that A is a "Father" without referencing an "A isFatherOf B"
>statement? However if predicates were coordinate with *the rule* then the
>statement "A is-a Father" exists with or without a statement that "A has-this
>C" where "C is-a Child" and "C is-this B". Note that all predicates are verbs.
>IOW "isFatherOf" is merely shorthand, in no way definitive itself.
> I maintain this odious shorthand completely screws up the industry as these
>non-English psuedo technical artificially-intelligent programmer words like
>"isFatherOf" overwhelm us like bunnies. It's so bad now we need tools to help
>us understand our own damn language - what a towering joke it all is-a! (03)
[EJB] the fact is that there is no difference between saying "A is a Father"
and "A isFatherOf someone". The meaning of the ROLE concept "Father" is that
it is a relationship to someone. You can specify the "someone" existentially,
in which case Father is a classifier predicate defined by "is the father of
SOME person", i.e.
(forall (A) (iff (Father A) (exists (c) (isFatherOf A c))))
Yes, you can define the Father class in terms of the isChildOf relationship
instead:
(forall (A) (iff (Father A)(and (Male A) (exists (c) (isChildOf c A)))))
Note that the above requires (Father A) is only true if A is also male. (04)
But depending on how you define Child, it is either an independent predicate
(e.g., Child is a Person whose Age is less than 16 years), or a shorthand for
isChildOf some Person.
Note also that if Child is defined existentially
(forall (C) (iff (Child C) (exists (P) (isChildOf C P))))
then it follows that the Child predicate is equivalent to the Person predicate,
since every person is the child of someone. (05)
If you define Child independently, e.g. in terms of age, then your would-be
predicate "has-this" is semantically empty. I can't tell 'has-this' child,
from 'has-this' house or 'has-this' headache. It is simply a statement that
there is some relationship. "hasChild" is a meaningful binary relation. (06)
In so many words, what you wrote is logically and semantically confused. That
said, you are hardly alone. Out in database/information modeling land there is
as much nonsense published about "roles" as there is substance. Many would-be
knowledge engineers are confused by the fact that "Father" and "person" are
both "nouns" in natural languages, but only Person is a predicate. In a
similar way, we were taught in 5th grade that "has" is the "verb" in "Mary has
a little lamb", so therefore "has" must be a binary relation. The relationship
between linguistic constructs and semantic constructs is complicated, and this
role and "has" stuff is one of those 'faux amis' things in the divide. (07)
My favorite example, born of a standards committee debate many years ago:
- "manager of (bank)" is a "role" in a binary relation: (person) is manager of
(bank), where the (person) role is called "manager", and the thing that plays
the (bank) role must be identified.
- "bank manager" is a class predicate defined by a role: (person) who is
manager of SOME bank, in which the "bank" role is existentially quantified.
- "the manager of the Piccadilly branch of ING" is a class predicate that
subtypes "bank manager", by replacing the existential with a constant:
(person) who is manager of ING-Piccadilly. (08)
I don't have time to address the rest. I would only say that you and Matthew
are talking past each other. In the immortal words of the logician/semanticist
Haim Kilov, "I won't agree with anything you say, unless you first define your
terms." That is the problem here -- you two have different understandings of
some of the critical terms used in conveying your intent, and on this exploder
this seems to be a common occurrence, requiring multiple interchanges to
resolve. (09)
-Ed (010)
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