Re: [ontology-summit] Roles, Fillers, and Role Relations

[Patrick Cassidy <ontopacas@xxxxxxxxx>]

MatthewW:

 

First things first:

[PC]  >>    Trying to formally capture all of the intuitions about different kinds of ‘Role’ takes a bit of work, and can be done in different ways. 
>>     My goal is to find a logically sound representation that can support language understanding, and also be translated into
>>    other representation formalisms when needed.
>  [MW]: The first thing you need to do then is to disambiguate different usages of the term.

Right!!!  As we all know, In an ontology a term has a meaning that is only what the axioms specify it to be. The documentation is for human comprehension.   The term ‘role’, like the term ‘process’ seems to have a different definition in every independently developed ontology that I have looked at.  That is why I avoid the term ‘Process’ by itself in COSMO, and use combined terms to avoid confusion.  It seems that perhaps I will also have to avoid the term ‘Role’ (and change it to something else) for the same reason.

 

[PC] >>     One reason to treat Roles as all subtypes of the generic ‘Role’ (and instance of ‘RoleType’) is that
>>  one can be agnostic, when convenient, of just how many subclasses there might be.  The role ‘Student’ for example
>> may have many subtypes and many role fillers, and many 4D worms as subtypes.  If one wanted to think of
>>  individual 4D worms as individuals, not classes, then it would be necessary to specify that a particular Person fills a Role
>>  in some specific a TimeSlice of some specific 4D worm, which would then have to be instantiated.  I find it easier to just
>>  specify that an instance of  Person is an instance of ‘Student’ in some time interval, and specify the time interval. 
>>  This way I don’t have to identify the specific 4D worm.

[MW] > Sorry, to me it is not coherent to think of 4D worms as classes. It just does not compute.

First, to respond to John Sowa’s comment:

[PC] >> That is not the usage in COSMO; if one views an ‘instance’ of a Role

>> as a specific whole 4D worm through space-time, then this is actually

>> represented in COSMO by a class which is a *subtype* of the generic

>> ‘Role’. I think that this has the same effect as your treatment, using

>> a different notation.

> 

[JS] >Talking about 4D worms is an interesting metaphor that might be used to illustrate

> some formal analysis.  But worms are too slippery to support precise statements,

> analysis, and reasoning.

  A qualified agreement – I do use it primarily as a visual image that can help clarify discussion,

but the concept does not show up (yet) as formally defined in COSMO.  The qualification is that

I am not sure it *can’t* be made precise, but I am queasy about treatments of 4D worms as entities

when they assert that anything within that region of space-time must be *part* of that entity. 

That can present what to me are serious problems.

 

Regarding Matthew’s ‘does not compute’ – the COSMO representation  is actually quite accurately and consistently computable, though it may violate some intuitions.

As I mentioned before, each  lowest-level subtype of Role (i.e. a subtype of Role one that that has no subtypes) can be viewed as a class consisting of the time slices of that Role.   The reason this seems nonintuitive may be because time slices of individual PhysicalObjects are *not* ‘instances’ of that individual – and that points out one of the great differences between physical individuals and Roles, in that physical Individuals are considered to have diachronic identity, whereas Roles can have as fillers many things of different identity.   But the logic is coherent.

 

[PC] >>      That Is not the usage in COSMO; if one views an ‘instance’ of a Role as a specific whole 4D worm through
>> space-time, then this is actually represented in COSMO by a class which is a *subtype* of the generic  ‘Role’.
>>    I think that this has the same effect as your treatment, using a different notation.
>
[MW ] > OK. That clears up some of the confusion. I use the term participant for what you call role.

Thanks for the discussion, and the pointer to the HQDM framework.  I will have to look more closely at your ‘participant’ and ‘state_of_XXX’ to seen how those concepts align with COSMO.

 

To reiterate, this thread started when I mentioned that I find it convenient, and linguistically  perspicuous, to allow a merged subtype of both ‘Role’ and PhysicalObject.  Some expressed reservations about that.  But, it seems to me, that to properly analyze the issue, one needs to be sure that all the relevant relations among the relevant terms in different ontologies have  been identified.  Alas!  That takes up more time than most of us can easily spare.  Nevertheless, this did help sharpen my own understanding of where misunderstandings can arise, and hopefully how to avoid them and to make my ontology elements more precise.  Thanks to all.

 

Pat

 

Patrick Cassidy

MICRA Inc.

cassidy@xxxxxxxxx

908-561-3416

 

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