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" (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. (01)
This may be one point of terminology work spilling some ink (or electrons)
over.
"existential functional dependency"??? (02)
Pat (03)
Patrick Cassidy
MICRA, Inc.
908-561-3416
cell: 908-565-4053
cassidy@xxxxxxxxx (04)
> -----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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