Re: Definitions and provenance and invariance

Hi Daniel, Graham,

I think we all agree that we want a simple and easily understandable 
model. That is clear.

However, this is a discussion largely around terminology and a bit about 
building blocks. I hope it will converge soon to some clear terms.

cheers
Paul

Daniel Garijo wrote:
> Hi Graham,
>
>     In the world of ontologies, it is the simple, small ontologies that
>     say very little, and leave little room for disagreement, that are
>     widely used (FOAF, SiOC, DC, VOID, etc.).
>
> That is completely true, and that is why I like your proposal, because
> it is simple and easily understandable. I also like the notion of
> "wraping" the provenance statements around a Provenance resource,
> because this way you can describe them with provenance too. From my
> point of view, if the core of the PIL is simple, it will be widely adopted.
>
> Best,
> Daniel
>
> 2011/6/14 Graham Klyne <GK@ninebynine.org <mailto:GK@ninebynine.org>>
>
>     I'm getting a distinct feeling that the reductionist focus on trying
>     to define terms in isolation is not helping us move towards a useful
>     consensus.  I feel it is tending to force our attention to matters
>     that are not important and where we might reasonably have different
>     views, rather than on those matters where we already are pretty much
>     agreed. I'll try and explain why, then I'll offer a an alternative
>     approach.
>
>
>     The problem:
>
>     The more precisely one tries to define a concept, the more there is
>     in the definition to disagree with, or the fewer real-world entities
>     actually conform to that definition.  In model theoretic formalisms,
>     one can never completely constrain the definition of a term to limit
>     the satisfying interpretations to just one possible referent for
>     that term (cf. "The chief utility of a formal semantic theory is not
>     to provide any deep analysis of the nature of the things being
>     described by the language [...] but rather to provide a technical
>     way to determine when inference processes are valid" -- Pat Hayes,
>     RDF Model Theory, http://www.w3.org/TR/rdf-mt/).
>
>     In the world of ontologies, it is the simple, small ontologies that
>     say very little, and leave little room for disagreement, that are
>     widely used (FOAF, SiOC, DC, VOID, etc.).  (There are exceptions,
>     such as the Gene Ontology family, but the difference here is that
>     such ontologies are being used within a community to encode a
>     substantial body of evolving domain knowledge.)
>
>     In natural language (which we are are using to create our
>     definitions), W V O Quine compellingly argues (in at least one of
>     his essays in "Ontological Relativity") that it is not possible to
>     constrain meanings for individual terms in ways that allow for
>     correct assessment of the truth of any sentence, and that the role
>     of words does not necessarily map one-to-one between languages that
>     have comparable expressive power (Quine describes the role of number
>     words in western languages and Japanese).  But what we can do more
>     easily is agree (or not) about the truth of complete sentences.  (As
>     I write this, I don't have my copy of Ontological Relativity to
>     hand, so am relying on memory for the references.)
>
>
>     Proposal:
>
>     What I propose, and I think it parallels a thought that Jim has
>     already expressed
>     (http://lists.w3.org/Archives/Public/public-prov-wg/2011Jun/0015.html,
>     and elsewhere), is that we look at a minimal model of related
>     provenance concepts, and agree something about the combined meanings
>     of the concepts and their relationships.  For the purposes of
>     exposition, I shall focus on time-varying properties, but I believe
>     the approach can generalize to any variation in a resource's property.
>
>     My core structure is:
>
>       Dynamic resource
>         |
>         v has view
>         |
>       View resource
>         |
>         v has provenance
>         |
>       Provenance resource
>
>     Where the possible sets of differently labelled resources are not
>     disjoint.  I think the key criterion that we are trying to express
>     is that the relation has provenance carries a requirement of
>     invariance between the view resource and the provenance resource.
>
>     Suppose that the "Dynamic resource has a number of different
>     observable properties, some of which do not change over time, and
>     others which do.  Then the View resource would be a resource for
>     with a similar set of properties such that do not change over time,
>     but correspond to the dynamic resource properties at a given time
>     (including properties that do not change over time).  If the Dynamic
>     resource does not change over time, then it may also serve as its
>     own view resource:  the has view property can be reflexive.
>
>     The provenance resource is an assertion about the properties of the
>     view resource.  I believe the key requirement that we try to capture
>     is that the properties about which the provenance resource makes
>     assertions are invariant - there is no assertion in the provenance
>     resource which is not always true of the view resource.
>
>     ...
>
>     This could (and should) be cast in more mathematical terms (e.g.
>     resource properties as functions of time t), but I think it would be
>     quite easy to formally express the required constraints and I'll
>     skip doing so in this email.
>
>     In writing this, I think it reflects quite closely what Luc has been
>     describing through IVPTs, or whatever, but in in considering the
>     different resources and relationships between them I find it much
>     easier to focus on and express what (I think) is important.
>
>     #g
>     --
>
>
>

Received on Thursday, 16 June 2011 13:45:52 UTC