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Re: Disjointedness of FRBR classes

From: Tom Baker <tbaker@tbaker.de>
Date: Wed, 26 Oct 2011 14:27:26 -0400
To: "gordon@gordondunsire.com" <gordon@gordondunsire.com>
Cc: Karen Coyle <kcoyle@kcoyle.net>, public-lld@w3.org
Message-ID: <20111026182726.GA25630@julius>
On Wed, Oct 26, 2011 at 04:03:20PM +0100, Gordon Dunsire wrote:
> > property "is realizer (corporate body) of" is disjoint with properties:
> > - has name of the corporate body
> > - has number associated with the corporate body
> > - has place associated with the corporate body
> > - has date associated with the corporate body
> > - has other designation associated with the corporate body

Okay, so we have [1]:

    <frbrer:P2012> <rdfs:label> "is realizer (corporate body) of"@en .
    <frbrer:P2012> <rdfs:range> <frbrer:C1002> .  
    <frbrer:P2012> <rdf:type> <owl:ObjectProperty> .
    <frbrer:P2012> <rdf:type> <owl:NamedIndividual> .
    <frbrer:C1002> <rdfs:label> "Expression"@en .
    <frbrer:C1002> <rdf:type> <owl:Class> .
    <frbrer:C1002> <rdf:type> <owl:NamedIndividual> .
    <frbrer:P2012> <rdfs:domain> <frbrer:C1006> . 
    <frbrer:C1006> <rdfs:label> "Corporate Body"@en .
    <frbrer:C1006> <rdf:type> <owl:Class> .
    <frbrer:C1006> <rdf:type> <owl:NamedIndividual> .
    <frbrer:P2012> <owl:propertyDisjointWith> <frbrer:P3045> .
    <frbrer:P3045> <rdfs:label> "has place associated with the corporate body"@en .
    <frbrer:P3045> <rdfs:domain> <frbrer:C1006> .
    <frbrer:P3045> <rdf:type> <owl:NamedIndividual> .

and then:

    <frbrer:P2012> <owl:propertyDisjointWith> <frbrer:P3045> .

I'm struggling to see the interoperability gains of putting all these "disjoint
property" statements into the definitions of the base vocabulary.  Triples
about disjointness are 45% of the 3930 triples in [1].

> Property disjointness is given where the value of the object of an instance
> triple should not be interpreted as referencing the same thing as for an
> instance triple using a different property but with the same subject. 

As OWL2 puts it: "two properties are disjoint if there are no two individuals
that are interlinked by both properties" [2].  I can understand why one would
want to apply such precise semantics in controlled environments (e.g., a
cataloging department) for the purposes of controlling the quality of data
produced, but I do not see the benefit of imposing such strong semantics on the
rest of the world by including them in the very definitions of properties and
classes.  

To my way of thinking, the presence of these strong semantics seems to tell the
world that nobody should even _think_ of using these vocabularies unless they
really really know, understand, and subscribe to the precise interpretation
encoded therein and are confident they can apply it correctly (and that
speakers of Chinese, Spanish, and Arabic should hope the translations are
good).  The semantically strong definition seems to imply that these
vocabularies are really only intended for use by trained, professional,
English-speaking library catalogers using OWL reasoners, and that nobody should
even think of building on FRBR with additional properties without defining them
with the same high degree of precision.

If so, that feels like a missed opportunity, because FRBR is potentially very
useful outside of that relatively small world.  Defining FRBRer without all
this disjointness, on the other hand, would not at all preclude the application
of strong interpretations when really needed in specific contexts, such as
controlling the output of cataloging departments.

In the end, though, I wonder if this strong disjointness is really supported by
the FRBR model itself [3]?   For example, I read:

    "On a pragmatic level, defining work as an entity in the model serves a
    number of purposes. It enables us to give a name and draw relationships to
    the abstract intellectual or artistic creation that encompasses all the
    individual expressions of that work. ....  It is the entity defined as
    work, therefore, that provides us with this grouping capability. ... On a
    practical level, the degree to which bibliographic distinctions are made
    between variant expressions of a work will depend to some extent on the
    nature of the work itself, and on the anticipated needs of users and on
    what the cataloguer can reasonably be expected to recognize from the
    manifestation being described." 

In such places, the language of FRBR seems to suggest less a rigid ontology of
the world "as it is" and more a set of distinctions that have value because
they are useful in a pragmatic sense, e.g., in splitting parts of a description
into separate bundles that can be maintained and referenced in a more
distributed manner.  As Barbara Tillett and Ron Murray put it [4]:

    E-R and OO modeling may be used effectively to create information systems
    based on an inventory of "things of interest" and the relationships that
    exist among them. Unfortunately, the things of interest in Cultural
    Heritage institutions keep changing and may require redefinition,
    aggregation, disaggregation, and re-aggregation. E-R and OO modeling as
    usually practiced are not designed to manage the degree and kind of changes
    that take place under those circumstances.

Their reference to WEMI entities as "sub-graphs" which "reproduce bibliographic
characteristics found useful by catalogers, scholars, other educationally
oriented end-users, and to varying extents the public in general" -- as
"views", or as "groups of statements that occupy different levels of
abstraction" -- suggests a more flexible (and useful) basis for a formal
expression of FRBR defined, perhaps, more along the lines of minimal semantic
commitment.

Tom

[1] http://triplr.org/ntriples/iflastandards.info/ns/fr/frbr/frbrer/frbrer.rdf
[2] http://www.w3.org/TR/2009/REC-owl2-primer-20091027/#a_DisjointObjectProperties
[3] http://www.ifla.org/publications/functional-requirements-for-bibliographic-records
[4] http://www.ala.org/ala/mgrps/divs/lita/publications/ital/prepub/index.cfm

-- 
Tom Baker <tom@tombaker.org>
Received on Wednesday, 26 October 2011 18:28:02 GMT

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