PatH -
I am not particularly worried about terminology, but I would sure like to
avoid these unproductive terminology discussions by fixing on some term that
would not generate caustic responses. I will use any term that is agreeable
to the community, I was just using a term that seemed responsive to the
point of the query. I am interested in the substance of the issue (how to
use such assertions), and no one has yet commented on that. Is your
suggestion "forall-exists assertions" or "Skolem assertions"? Of the two, I
prefer the former. Your point about "functional" is well taken, it could be
misleading. (01)
Pat (02)
Patrick Cassidy
MICRA, Inc.
908-561-3416
cell: 908-565-4053
cassidy@xxxxxxxxx (03)
> -----Original Message-----
> From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx [mailto:ontolog-forum-
> bounces@xxxxxxxxxxxxxxxx] On Behalf Of Pat Hayes
> Sent: Friday, December 14, 2007 2:17 AM
> To: Patrick Cassidy
> Cc: [ontolog-forum]
> Subject: [ontolog-forum] Existentials (WAS: Re: brainwaves (WAS: to
> concept or not to concept, is this a question?)
>
> >John,
> > Yes, it will be useful to agree on some term to refer to logical
> >assertions implying existence of one entity dependent on existence of
> >another. I usually hear those assertions referred to as simply
> >"existentials" or "existential assertions"
>
> By who? That usage is incorrect. An existential
> assertion is simply that something exists. What
> you are talking about here are AE (forall-exists)
> assertions: for every X there is a Y.
>
> >(or, in a database context, as
> >"integrity constraints"). If there is no objection, we can use
> "functional
> >dependency", but it would be nice to have a term that includes the
> word
> >"existential" to emphasize the central importance of that logical
> symbol in
> >the assertion.
>
> It is no more central than the universal. It is
> exactly your emphasis on one of the two
> quantifiers which is creating the confusion. Also
> it need not be functional: that is the assertion
> that for every X there is a *unique* Y. However,
> if it is functional, then one need not even use
> the existential quantifier, since the use of an
> explicit function stands in its stead.
>
> > This may be one point of terminology work spilling some ink (or
> electrons)
> >over.
> > "existential functional dependency"???
>
> Redundant. If its functional it must be
> existential (in your sense). If you are seriously
> worried about terminology, a good term for these
> might be Skolem assertions.
>
> Pat
>
> >
> >Pat
> >
> >Patrick Cassidy
> >MICRA, Inc.
> >908-561-3416
> >cell: 908-565-4053
> >cassidy@xxxxxxxxx
> >
> >
> >> -----Original Message-----
> >> From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx [mailto:ontolog-forum-
> >> bounces@xxxxxxxxxxxxxxxx] On Behalf Of John F. Sowa
> >> Sent: Thursday, December 13, 2007 11:16 PM
> >> To: [ontolog-forum]
> >> Subject: Re: [ontolog-forum] brainwaves (WAS: to concept or not to
> >> concept, is this a question?)
> >>
> >> Pat,
> >>
> >> That kind of connection is very common in databases and
> >> knowledge bases. I agree that some way of describing it
> >> clearly and simply would be useful.
> >>
> >> But I agree with Chris that using the term "existential
> >> qualifier" is confusing. Some people use the term
> >> "dependent entity", but that is also confusing, because
> >> it would imply that any talk about a child would introduce
> >> the two parents as "depedents".
> >>
> >> There is, however, a common term in database theory:
> >>
> >> functional dependency.
> >>
> >> In a relational database, for example, some columns of a table
> >> might be "functionally dependent" on other columns. For an
> >> employee relation, the columns for manager, department, and
> >> salary are functionally dependent on the employee. That
> >> means, for any employee x, there are functions f1, f2, f3,
> >> such that
> >>
> >> f1(x) is the manager of x
> >>
> >> f2(x) is the department of x
> >>
> >> f3(x) is the salary of x
> >>
> >> I suggest that we use the term "functional dependency"
> >> for such entities.
> >>
> >> John
> >>
> >>
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