Re: SUO: Re: More terminology
Terminology management:
John F. Sowa wrote:
> Pierre,
>
> PG>Are you pissed? I apologize.
>
> No. I'm not pissed. I'm just frustrated with the endless
> rehashing of debates about terminology.
>
I agree that we need a standardized terminology list for
this discussion group. I seem to recall that one of us proposed
to set up such a list over a year ago, but don't recall
whether anything concrete was decided.
Can we use this thread to decide how to create a standard
terminology for this group? Does anyone have experience setting
up a WIKI? If not, I will volunteer to maintain a terminology
page on my site (simple list-nothing fancy) until someone
else sets up a better hypertext version.
As one starting point, I would suggest a careful definition of
the terms "class" and "relation" and "predicate" (which
may require definition of "term" and "sentence").
For "class" and "relation" I would prefer the usage that is
given for KIF classes. It may not be the same as VNBG classes,
but I think it is the most common use of the term - no?
The definitions from the KIF site are attached below. Any
dissenters? (silly question?) If the majority prefer this
definition, and there is a minority that prefer a different
usage, I would suggest creating a different term for the
alternative usage.
Pat
--
=============================================
Patrick Cassidy
MICRA, Inc. || (908) 561-3416
735 Belvidere Ave. || (908) 668-5252 (if no answer)
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internet: cassidy@micra.com
=============================================
from:
http://www-ksl.stanford.edu/knowledge-sharing/ontologies/html/frame-ontology/CLASS.html
CLASS
Documentation:
A class can be thought of as a collection of individuals. Formally, a
class is a unary relation, a set of tuples (lists) of length one. Each
tuple contains an object which is said to be an instance of the class.
An individual, or object, is any identifiable entity in the universe
of discourse (anything that can be denoted by a object constant in
KIF), including classes themselves.
The notion of CLASS is introduced in addition to the relation
vocabulary because of the importance of classes and types in knowledge
representation practice. The notion of class and relation are merged
to unify relational and object-centered representational conventions.
Classes serve the role of `sorts' and `types'.
There is no first-order distinction between classes and unary
relations. One is free to define a second-order predicate that makes
the distinction. For example, (predicate C) could mean that the unary
relation C should be thought of more as a property than as a
collection of individuals over which one might quantify some
statement. Logically, all such predicates would still be instances of
the metaclass CLASS.
The fact that an object i is an instance of class C is denoted by the
sentence (C i). One may also use the equivalent form (INSTANCE-OF i
C). This is not equivalent to (MEMBER i C).
An instance of a class is not a set-theoretic member of the class;
rather, the tuple containing the instance is a element of the set of
tuples which is a relation.
The definition of a class is a predicate over a single free variable,
such that the predicate holds for instances of the class. In other
words, classes are defined intentionally. Two separately-defined
classes may have the same extension (in this case they are = to each
other). It is possible to define a class by enumerating its instances,
using KIF's set operations. For example, (define-class primary-color
(?color)
(member ?color (set red green blue)))
Subclass-Of: Relation
========================
RELATION
Documentation:
A relation is a set of tuples that represents a relationship among
objects in the universe of discourse. Each tuple is a finite, ordered
sequence (i.e., list) of objects. A relation is also an object itself,
namely, the set of tuples. Tuples are also entities in the universe of
discourse, and can be represented as individual objects, but they are
not equal to their symbol-level representation as lists.
By convention, relations are defined intensionally by specifying
constraints that must hold among objects in each tuple. That is, a
relation is defined by a predicate which holds for sequences of
arguments that are in the relation.
Relations are denoted by relation constants in KIF. A fact that a
particular tuple is a member of a relation is denoted by
(<relation-name> arg_1 arg_2 .. arg_n), where the arg_i are the
objects in the tuple. In the case of binary relations, the fact can be
read as `arg_1 is <relation-name> arg_2' or `a <relation-name> of
arg_1 is arg_2.' The relation constant is a term as well, which
denotes the set of tuples.
Subclass-Of: Set