Instead of "SituationInvolvesRole"
how about terms like "may-be:in" or "may-have:some" or
"may-have:a" to relate concepts? Here's
an example of the verb:article / verb:preposition
methodology I've spoken of, in a model for 'newspaper' that I put
together the other day that I think demonstrates how accessible this
methodology can be.
thanks/jmc
On 2/26/2014 8:37 AM, Barkmeyer, Edward
J wrote:
Pat,
You
wrote:
>
You can treat each ‘Role’ as a relation with a ‘range’, but
one must never confuse a (non-unary) relation with a class
(type). But One can alternatively have roles as types (not
as relations), in which case one would have a different
relation to relate some Object instance with its ‘Role”
type.
If
I understand this correctly, I agree.
If,
as William suggests, you model the ‘domain verbs’ as classes
of states/activities, then a ‘role instance’ is a pair:
(state/activity instance, role player), and the Role is a
binary relation that those pairs satisfy. I think this is
what you mean by “treating each Role as a relation”.
The
alternative is that a Role is a ‘type’ whose instances are
‘things in the process of playing the role’, i.e.
“participations”. Each ‘role instance’ is an instance of
the Role type. Some binary relation, e.g.,
SituationInvolvesRole, relates each ‘role instance’ to the
state/event in which the Role is instantiated/played. That
is, the instances of SituationInvolvesRole are pairs of the
form (state/activity instance, role instance). It is a
necessary property of role instances that they participate
in exactly one such pair. Further, each role instance is
related to the object that plays the Role in that
state/activity by a different relation ThingPlaysRole, and
its instances are pairs of the form (role player, role
instance). I understand this to be what you mean by your
second option above.
Note
that the mulitiplicity rule for participation of a role
instance in SituationInvolvesRole and ThingPlaysRole pairs
may depend on the role itself, and the modeler’s view. One
can consider that there might be states/activities that have
‘optional roles’ – roles that may or may not be played in
various instances of the ‘situation type’ that defines the
roles. Further, there may be multiple undistinguished roles
in a state/activity, so the same Role (type) could have
multiple role instances in the same state/activity. One
might, I suppose, alternatively model the latter as one role
instance that is related to multiple role players via
ThingPlaysRole. (I would strongly prefer multiple role
instances of the same Role type to multiple players of the
same role instance, but I think that is some “intuitive
ontological commitment”. I don’t know that multiple players
of the same role instance would produce problems; I just
“would not do that”.)
Note
also that, in either case above, the Role can have
refinements, e.g. captain of ship is a narrower role than
officer on ship. If you model the officer role as a
relation (Pat’s first option), e.g., an OWL objectProperty,
then the captain relation is a owl;subpropertyOf the officer
property. Similarly, if you model the officer Role as a
type/class (Pat’s second option), then the captain role is a
owl:subclassOf the officer class.
Final
Note: Pat’s proposed Role class, e.g., “being an officer”,
has instances that are the participations in
states/activities; its instances are not the role players
themselves. The class Officer defined by “person who is an
officer on some/any ship” has instances that are the role
players themselves. They are significantly different
classes.
Pat
wrote:
>
By
now I would hope that discussants on this list would be
careful not to imply that there is some necessary formal
meaning for any linguistic term. In an ontology, the entity
labels mean only what the logic says they mean.
I
fully agree. William’s point was that, in addition, there
is no necessary formal model for linguistic parts of
speech: A verb can be a Class, a noun can be a Property.
Put another way, when you title an OWL Class ‘Person’,
‘Person’ is NOT an English word; it is an identifier/term in
the OWL language, which is radically different from
English.
(In
the early 1990s, I railed in vain against an ISO TC184/SC4
modeling dictum that did not permit the use of the English
word ‘product’ in the definition of the EXPRESS symbol
‘product’ because “the definition would be circular”. That
rule demonstrated that the people making the rules did not
understand what they were doing.)
-Ed
P.S.
According
to Matthew West (separate discussion), the ISO 15926
ontology makes the ‘role instances’ a class of ‘temporal
parts’ of the role players, using TemporalPartOf for
ThingPlaysRole; similarly, it makes the role instances
‘spatial parts of’ the situation objects, using
SpatialPartOf for SituationInvolvesRole (with the inverted
‘reading’). So the 15926 approach matches Pat’s second
option.
One
point regarding Ed Barkmeyer’s comment:
[EB]
> Right! This is even worse than the problem of
making the role a subtype of its ‘range’:
>
the things that can play the role.
You can treat each ‘Role’ as a relation with a ‘range’,
but one must never confuse a (non-unary) relation with a
class (type). But One can alternatively have roles as
types (not as relations), in which case one would have a
different relation to relate some Object instance with its
‘Role” type.
I
actually use the latter formalism in COSMO, and I don’t
find any logical inconsistencies. Perhaps you have in
mind some examples where this creates some problem.
[EB}
> This makes the range type a subtype of ‘role’,
>
which is properly not a ‘type’ at all.
Well,
in the COSMO treatment that is not implied. In COSMO the
type ‘Role’ is a top-level type, and many things such as
‘Student’ can be represented as both a subtype of ‘Person’
(PhysicalObject) and of ‘Role’ (a time-dependent entity).
This means that an instance of ‘Student’ can only be used
in an assertion when the valid time interval of the
assertion is within the time interval of that ‘Student’
role. The general class of ‘HumanRole’ is used as the
parent class for all Roles filled by humans, and ‘Student’
and ‘Teacher’ are a subtypes of ‘HumanRole’. Every
subtype of ‘HumanRole’ is a subtype of both Human and
Role.
As for the comment that a ‘Teacher’ can be a computer,
in COSMO an object of that type would not be an instance
of class ‘Teacher’, but would be represented as an
instance of some subtype of computer program or computer
or some combination thereof (depending on what you intend
to refer to). It can be related to the human role by
some relation such as ‘performsTheFunctionOfa’. Of
course, one can, in informal speech, use any label for any
entity, but in the Ontology the term labels are unique
with unique meanings. The ontology type ‘Student’ or
‘Teacher’ in COSMO can only refer to humans within the
time period when they are serving ion those roles. In
informal speech, they can refer to anything (e.g.
‘experience is the best teacher’).
By now I would hope that discussants on this list would be
careful not to imply that there is some necessary formal
meaning for any linguistic term. In an ontology, the
entity labels mean only what the logic says they mean.
This COSMO ‘Role’ formalism is adopted for a couple of
reasons: to keep the ontology as close as possible to
linguistic usage (we say that ‘the student went to class’,
not ‘the person who was playing the role of student went
to class’), and to allow the most convenient
representation within the OWL formalism. For many
purposes, the ontology will need to be converted into FOL,
but I believe that there are good reasons to have an OWL
version as well as an FOL version, so the first version of
COSMO is being developed in OWL, with the goal of being as
perspicuous as is consistent with logical consistency.
Converting from OWL to FOL will be the easier path to
having both formalisms available.
The general problem I have with discussions such as these
is that they are occurring outside of any specific example
application that can provide a test or at least some
constraints on proposals for the utility of some
formalism. I would like to see more examples from
practical uses to help decide what formalism is useful in
what situation.
Pat
I
intended to add this to my previous email.
William
wrote:
>
Nothing wrong with the word 'attribute', or the way CHEN
and now
> everyone uses it.
>
> EXCEPT FOR Tthe BIG MISTAKE of thinking that a
certain kind of thingie
> (say blue) IS an attribute, just because it **can
play that role.**
Right!
This is even worse than the problem of making the role a
subtype of its ‘range’: the things that can play the
role. This makes the range type a subtype of ‘role’,
which is properly not a ‘type’ at all.
I
think the origin of this error is the specific
distinction in Chen’s model between ‘attributes’, as
relationships to ‘values’ (computational
representations), and ‘relationships’ as relationships
to ‘entities’. If you view the ‘value’ as JUST the
computational entity – an integer, a real number, a
character string -- then the ‘role’ actually gives it
useful semantics. It is not that ‘blue’ IS an attribute
of things, but rather that the string “blue” AS an
attribute refers to a color of things.
In
Sjir Nijssen’s approach, by comparison, Color is a
‘non-lexical object type’ and Blue is an instance of
that type, but, when converting that model to a database
schema, we may decide that the “NOLOT” Color can be
represented by a ‘lexical object type (LOT)’ that is
said to be a subtype of String. This sorts out the
distinction between the semantic Blue and the string
“blue”. In a similar way, the ISO 11179 metadata model
distinguishes between the ‘conceptual value’ Blue and
the ‘data element value’ “blue”.
But
we can think of this as a progression of understanding –
Chen (1976), Nijssen (1982), ISO 11179 (1998).
-Ed
On Mon, Feb 24, 2014 at 11:10
PM, John F Sowa <sowa@xxxxxxxxxxx>
wrote:
Ed, Pat C, William,
.....
WF
>
Nothing wrong with the word 'attribute', or the
way CHEN and now
> everyone uses it.
>
> EXCEPT FOR Tthe BIG MISTAKE of thinking
that a certain kind of thingie
> (say blue) IS an attribute, just because it
**can play that role.**
I agree. I would use a dyadic
relation named HasAttr to relate
an entity to something called an attribute of that
entity.
An attribute of something is only an attribute
when it is viewed
in the role of the second argument of a relation
named 'HasAttr'.
Right, I have been saying
the following on this forum for almost two
years:
being an attribute is, in human language, not
a fixed feature of a word or a concept, except
for some of the words in some minority of
languages. In others, 'beauty' and
'beautiful' and 'is beautiful' are expressed
with exactly the same word, and the role in
the sentence is market either by word position
(in a positional language) or a particle that
shows this (in a tagged language).
In a very mongrel language like English,
things are very complex, because multiple
patterns are in play at the same time, on a
word-by-word basis. For example, some words,
like 'German', and the same as nouns and
adjectives. He is German, He is A German,
while others that occupy the same semantic
space, like English and Scottish, are not the
same, but have to turn into English Person and
Scot.
psycholinquists
are examining how various language-related
disabilities are manifested by speakers of
different languages, and thus finding more
about what is the same and different about the
fundamental samenesses and differences between
thinking and speaking in different
languages. They don't use entities,
attributes, and relationships as their
foundation, nor parts of speech like nouns and
verbs. They tend to use theta roles.
Given
this, why would one want to insist that the
fundamental organization of thought or a
universal simple way to express propositions is
based on entities, their attributes, and their
relationships?
> In another
attibutive relation, the same thingie, blue,
can play
> the role of attributed to, such as in
'blue is a color.'
This raises the question
about instances of blueness. We'd like to say
the blue of your coat is darker than the blue of
the sky. So we need
to include instances of blueness in the
ontology: the HasAttr relation
relates a coat x to an instance of blueness y,
which we can relate to
another instance of blueness z of the sky.
Yes, this is yet another
role that 'blue' can plan. It can be the name
for a particular repeatable experience of
blueness.
The blue of my coat is, if I understand
correctly, what some metaphysicians are
calling 'tropes' these days.
" According
to trope theory, the world consists (wholly or
partly) of ontologically unstructured (simple)
abstract particulars or, as they are normally
called,
tropes. " Stanford Encyclopedia of
Philosophy
That is, it is a particular
but repeatable experience of blue. And, in
fact, if I understand, in this thought, 'my
coat' is there just to locate the blue
experience using a shared identifier, becasue
the experience of that blueness, along with
many other cues, is in fact one of the things
that underlies constructing the coat in
question out of our fundamental experiences.
Personally, I like this direction for
metaphysics, in that it brings it closer to
psychophysics and social psychology.
WF
> Did you ever
have clients who had trouble seeing that
'customer'
> was a role, and that so was 'vendor,' so
that the vendor and customer
> might be the same company?
Good old Aristotle was quite
clear about those issues. He
distinguished the "substance" -- such as
HumanBeing -- from the
"accidents" such as being blue or being a
customer, vendor, etc.
For an Aristotelian description of George
Washington, see slide 6
of http://www.jfsowa.com/talks/aristo.pdf
Yes, and this goes back to
some previous discussions here about natural
types, with which I also agree.
But I have found it harder to sell that idea
right off the bat than selling the
understanding that some words used to describe
things are actually describing roles of the
things (customer, scoutmaster) , and others
are not (person).
John
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