John, I have a few comments about your response, which I make below (01)
> From: "John F. Sowa" <sowa@xxxxxxxxxxx>
> Subject: Re: [ontolog-forum] Modal Ontological Representations
>
> Chuck,
>
> I have more sympathy for modal logic than Pat has, but I am
> skeptical about the need for modal logic in the ontology.
>
> CDT> I see that any system that has a non-trivial internal model
> > of reality is likely to have modal appreciations of that reality
> > as system state changes occur.
>
> I don't know what "modal appreciation" means, but I would agree
> that multimodal language is important for many purposes. Examples
> include an engineering project, in which there are requirements
> ('must' or 'shall'), options ('may' or 'can'), obligations
> ('should' or 'ought'), and all sorts of future or hypothetical
> questions. (02)
The particular set of cases I have in mind, that leads me to think of
multiple modal appreciations within a system, is in the world of
simulations. A complex simulation is a synthetic environment, whose
internal rules and realities are guided by the simulation and its
interpretation of an ontological viewpoint. As a simulation operates and
changes states, internally, some of those rules and realities will change -
possibly beyond the intended ontological viewpoint of the originator of any
one part of the simulation. Against this, the fact that the rules and
operations of the simulation ARE the rules of reality for the synthetic
environment described within it, shows that there are multiple modes of
that reality - each requiring some delta in the ontological representation
originally assumed for the system. The two solutions I can see for this
(assuming we want to have an ontology of the simulated world that is valid,
no matter where internal state changes and permutations take it) are to
either have (1) an overall ontology that captures the understood base
ontology modeled in the simulation, as well as all possible deltas to that
ontology that may occur as the simulation operates over time, or (2) some
sort of multi-modal ontology that changes to reflect the new reality as the
simulated world changes over time. (03)
> However, Kripke's version of possible-world semantics is not
> convenient for multimodal reasoning, because it very quickly
> leads to a tangled mass of "accessibility relations" for every
> mode. Furthermore, nobody can ever agree on a good (or even
> usable) collection of axioms for all the modal combinations.
>
> My preferred semantics for modal logic is based on a version
> by Michael Dunn, in which he focuses on the "laws" that generate
> the modalities: For each mode, there is some law or laws that
> determine what is necessary or possible (obligatory or permitted).
>
> In ontologies, some people talk about "essential" properties,
> but the word "essential" is a disguised modal operator.
> With Dunn's semantics, you can get rid of the word 'essential'
> by stating a law (or axiom) that makes that property essential.
>
> For a summary of Dunn's semantics and my extensions to it, see
>
> http://www.jfsowa.com/pubs/laws.htm
> Laws, Facts, and Contexts
>
> http://www.jfsowa.com/pubs/worlds.pdf
> Worlds, Models, and Descriptions (04)
Thank you, these should prove very useful, and I will look into them. (05)
>
> Note that I use the word 'context', but I give it a very simple
> formal definition: it's a box into which I put graphs. Then
> I show how those graphs can be used to characterize many other
> common uses of the word. I won't claim *all* uses of the word,
> because there are many uses that are too "creative" to be
> characterized in any clear and simple way.
>
> John (06)
I have to state that in all of this I am still a student, although I am
hungry to grow my knowledge. In that light, although I can usually follow
and see the value of any sort of ontological representation for the
purposes of describing a system (simulation, engineering system, document,
worldview, etc) that is knowable from the outset - the interesting
direction this takes for me (as a researcher in the world of simulations)
is in seeing how an ontology can be applied to synthetic environments where
the underlying rules of reality can change (since those rules are modeled,
and the models or interpretations-of-those-models can change, it follows
that the rules can change). (07)
Chuck (08)
Charles Turnitsa
Project Scientist
Virginia Modeling, Analysis & Simulation Center
Old Dominion University Research Foundation
(757) 638-6315 (voice)
cturnits@xxxxxxx (09)
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