[ontology-summit] Roles, Fillers, and Role relations

[Patrick Cassidy <ontopacas@xxxxxxxxx>]

Pat, Doug, Chris, Matthew -

   FWIW, the way Roles are handled in COSMO (an OWL ontology at present) has these characteristics:

   'Role' is a top-level first order type (class) not disjoint with anything but Attributes.  This can be a parent class of any other type.

    Thus one can have, for example, 'HumanRole' which is a subtype of 'Person' and 'Role'. (for example, 'Student' or 'President' or many others).  Then when one asserts that a 'HumanRole' participates in some action, there is both a RoleFiller (human) and  a 'Role" involved.  The logical implication is that the Person who plays that HumanRole is the participant.  Each instantiation of Role has a starting and ending time.

  There are also relations that relate the individual that plays a Role with the Role.  Most Roles will not have specific subtypes that combine the Role and its Filler in one type.  'HumanRole' is used because it is so important in everyday situations.

  There is also a RoleSituation, a subtype of 'PersistentState' (same as a 'state' in many terminologies).  This has some Role filler that is the subject of that situation.  One could (COSMO does not at this point) define a relation specifying how well that role filler fills that role in that specific RoleSituation.

  The point is that, although 'Role' is not itself a Physical concept, it can have subtypes that are physical objects.  This may differ from some ontologies (I think in DOLCE Role cannot have physical subtypes).  For compatibility with those ontologies, it might be necessary to include a subtype of  'AbstractRole' that corresponds to Roles that cannot have PhysicalObjects as instances.

  The rationale for this choice was to keep COSMO as close as possible to linguistic usage while minimizing ontological assumptions.  If one says the 'The Bishop sent a letter' and if "Joe Smith' is the Bishop, the logical implication is that Joe Smith sent the letter.  And vice-versa, one can say that 'Joe Smith' sent the letter, and the logical implication is that the Bishop sent the letter.  This means that if a Role performs an action, it is not necessary that that actions be performed **specifically** in the capacity of that role (the Bishop can send a personal letter).

   'Part' is a subtype of 'Role' and every 'Part' will be filled by an entity of some other type. Thus in this treatment, Pump101 would be a subtype of Role and also a subtype of 'Pump' (a physical device).  The physical objects that fill that Role at any time could also be referred to by the role name ('Pump 101 has failed').  The individual object that fills that Role may be identified, but it does not have to have a separate representation other than as 'Pump101'.  If it is separately instantiated (as most manufactured components would be), then it would be related to 'Pump101' by a role-filler relation, delimited by the starting and ending times it plays in that Role.

   Thus far in this discussion I have not noticed any requirements that  the COSMO treatment would not accommodate. Perhaps there are others?

  Pat Cassidy
  MICRA Inc.
  908-561-3416
  cassidy@xxxxxxxxx

 --------------- 

[Doug Foxvog]

> Pat,

> Makes sense to me.

> May we include an attribute on role signfying effect-iveness? Role

> effectiveness will partially depend on actor (if you have ever seen

> Peter Sellers play Hamlet).

> Jack

 

Ontologize the role playing as an object in its own right -- a Situation.

This would be a Davidsonian approach. Then you could make whatever assertions about it are needed.

 

[ChrisPartridge]

Pat,

 

It seems to me as if you are just playing with names here. If you want to call it a pump *role*, that is fine. But that what you are describing seems not to have the qualities that many people expect to be essential to roles.

These (like qua entities) do not have an individual identity and they do not do things, they are not agents. Whereas, for example, spatio-temporal entities come bundled with identity. What have I missed?

 

So the Hamlet example would better be  Jonathon Pryce's 1992 Hamlet. Or even better if we use Chairman (President, Bishop or Monarch) , the difference between Chairman and the Chairman of Goldman Sachs.

 

Also, not clear to me why you cannot kick your roles - as, again, they are spatio-temporal entities? When Ronnie Reagan was shot, people said they shot the President of the US, didn't they? They did not say thank goodness they only shot Mr Reagan - they could not shoot the President as he is a role.

 

Regards,

Chris

 

 

[Pat Hayes]

Very good question, Matthew. Let me try out an idea on you. Your P101 is actually a role played by a pump, rather than a pump itself. Think of it as being like Hamlet, as played by Lawrence Olivier (P101 as played by S3556). You can change actors, and Hamlet is still Hamlet - same role - and while Olivier is playing the role, he *is* Hamlet, at least in a sense. But this second "is" cannot be identity, since you can kick the actor, but you can't kick a role.

 

Both a pump and a pump-role are spatiotemporal entities, but they have different identity conditions. The identity of a pump, like any other physical object, is determined by the disposition of pieces of material stuff (metal, plastic, rubber), but the identity of  the role is determined by its interfaces to the rest of the system (being connected to this pipe in this place and operated by this controller, etc..)

 

You can identify a pump-phase (temporal slice) with a pump-role-phase, but you must not identify the actual individuals, so its safer to actually have a relation of 'functioning as' of the like to attach a role-playing thing to its role. Or, you can treat the role as a time-dependent property of the physical thing, but you will probably need a CL-style ability to have properties of properties if you go that (elegant) route.

 

Make sense?

 

Pat

 

 

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